The AM Forum

THE AM BULLETIN BOARD => Technical Forum => Topic started by: AE1CT on May 28, 2011, 10:57:35 AM



Title: vertical antennas
Post by: AE1CT on May 28, 2011, 10:57:35 AM
will vertical antennas work on am or is a dipole better. what about inverted v antennas? a friend of mine told me that a may pole vertical is a very good antenna to use on am....any thoughts on this topic.


Title: Re: vertical antennas
Post by: K1JJ on May 28, 2011, 11:42:24 AM
For 75M "local" work within 400 miles or so, a flat, straight dipole at 40' high (or more) is the best antenna you can get.  Feed it with coax or openwire - it makes no difference in performance except for band-hopping with the openwire.

An inverted vee is a close second, but a compromise because the legs start to cancel radiation as they come closer together. The average height is reduced too.

A vertical will be down maybe 15-20 db locally compared to the dipole. On 160M, va ertical can work well, but is still down to a dipole for local work.

Keep the dipole as far from large objects as possible, like houses, powerlines, etc. Trees are OK and almost invisible. The geometry of the dipole is important. No zig-zags or sharp angles. Strive to make it look like a "T" with the feedline coming straight down to the ground, if possible.  Your radiation pattern will then exhibit the best figure-8 pattern possible. Be sure to erect it broadside to your two favorite directions. (Southwest - NE for example)

Build your own and avoid the gimmick antennas offered for sale. A simple dipole with one center insulator and two end insulators fed with feedline is all you need.  Try to support the center. It will last longer in wind storms. Use 3/16" "aircraft" braided cable to go thru the tree limbs on each end. Rope will break after a short time due to friction from wind.

Do you have the room to erect a full-size 123' dipole for 75M?

Hope this helps.

Tom, K1JJ


Title: Re: vertical antennas
Post by: AE1CT on May 28, 2011, 12:11:02 PM
i dont have very tall trees in my yard (30 ft) high and the most room i have is probably 40 meters and i want to get on 80. i want to operate mosty sw from my location and there are no trees that will give me that direction. i want to get on the air but im in a position were i dont have a big yard or the tree hight that i need. WHATS a future AMer to do. any ideas would be greatly helpful.


Title: Re: vertical antennas
Post by: K1JJ on May 28, 2011, 12:19:23 PM
In your situation, the next best thing would be to hang a 123' long 75M dipole at 30' high. Stretch the flat legs out as much as possible (65' ?) and then drop the ends down towards the ground on each end. Pull the ends out as far as possible making a slope if you can.  This dipole will look like an inverted "U".  

At 30-40' high, the dipole is mostly omni-directional for local work anyway, so don't worry about the supports and directions for now.


This will work fine on 75M and also on 40M if you wish to feed it with openwire.  Some of the AMers do this and have great signals.   You can even load it up on 160M if you use heavier wire and good quality openwire.  Go to Home Depot and pick up a 500' spool of #10 or #12 black electrical insulated wire. Make the openwire and flat top from it and use a balanced antenna tuner for all band use.  If you use coax feedline, no tuner required, but you are limited to just 75M with the antenna as described.

T


Title: Re: vertical antennas
Post by: AE1CT on May 28, 2011, 12:33:38 PM
i was told that i can use a long wire and run it from tree to tree and feed it with 400 ohm ladder line and run a short 20 ft lenght on the open side of the ladder line, sort of like a windom. i mostly want to operate 40, 80 and 160 AM.  will this work for me with some reasonable results, im not looking to be a power house, i just want to be heard and have some fun on AM.


Title: Re: vertical antennas
Post by: K1JJ on May 28, 2011, 12:49:23 PM
Sure, anything will "work" and you will get many opinions.  Some of the guys run Windoms with excellent results.

But it's hard to beat the proven design and performance of a balanced dipole as I described. 

Receiving the other guy is half the battle as well as being heard when QRM and conditions get rough. Do all you can to get that antenna up as straight, flat and balanced.  A simple dipole is hard to beat.

Well, back outside for some more work... I'm black out.

T


Title: Re: vertical antennas
Post by: KZ5A on May 28, 2011, 03:39:06 PM
The usefulness of Verticals is highly dependent on local ground conductivity.   At my present QTH in Tyler, TX they work great because of the very high local ground conductivity,  At my "other" QTH in the mountains of New Mexico they are a waste of time due to the poor ground conductivity.

Dipoles are OK, but require 2 or 3 supports and if they are high enough to work DX off of the sides, they are dead off of the ends.  Not particularly a good plan if you only have one antenna.

Personally I prefer inverted V's for low band work.  They only require one support, are fairly forgiving of installation irregularities (like not having the two sections in line) and are generally omni-directional.   Here I'm blessed with several 60 -70 foot pine trees and have a 75M Double-Bazooka inverted V with the center up about 50 ft in a pine.  It "used to be" abt 60 feet up in the center but the support rope broke and the center dropped to about 50 ft and but stayed up so I've just left well enough alone.   

Not having tall trees to work with, the commonly available military surplus 4 foot fiberglass mast sections can be used as an economical center support for 40 or 50 ft before they get too wobbly.  If you pull the legs of the V out with around 120 degrees of separation you can get away with one guy.

I usually join or listen to the "Texhoma Traders Net" on 3890 on Saturday mornings and find that I generally can copy a greater percentage of the check-ins than most anyone else with my inverted V. 

Also, obsessing on making a dipole "flat"  is pointless and maybe even counter-productive.  Dipoles are installed in all sorts of configurations, V's, slopers, flat tops, bent on the ends.... what ever fits the available supports will work reasonably well.   The theory that they have to be flat and straight to work is a bunch of hogwash.   The higher it is in the center, the better it will work for DX.

Another popular approach to 160/80/40 is a full wave loop for the lowest band. feed with balanced line.   Whatever shape the available supports allow will work, but the closer to round the better.  I haven't tried one of these but a lot of hams swear by them.  Most people I've heard using one of these have them at 30 to 50 feet.

Copper house wire is heavy,expensive, and prone to stretching.  Copperweld is a better, cheaper, wire for antenna use. 
 
See http://www.thewireman.com/antennap.html 

73 Jack KZ5A


Title: Re: vertical antennas
Post by: K1JJ on May 28, 2011, 04:26:37 PM
Quote
Also, obsessing on making a dipole "flat"  is pointless and maybe even counter-productive.  Dipoles are installed in all sorts of configurations, V's, slopers, flat tops, bent on the ends.... what ever fits the available supports will work reasonably well.   The theory that they have to be flat and straight to work is a bunch of hogwash.   The higher it is in the center, the better it will work for DX.


Here we go again.

ANYTHING  will "work".  But compared to what?   The standard is a flat, straight dipole. Any departure from this is a compromise. Model it and see.

As we lower the legs of an inv V, they start to cancel radiation. Bring them down below 90 degrees apex angle and your input impedance starts to drop - continue to lower them until we get no radiation at all as the legs  become parallel as a feedline.  Also, the average height goes down as the legs are dropped and the take-off angle goes up.  Add a reflector or director and the front-to-back ratio (and gain) gets poorer with inverted V elements compared to flat  dipoles.

Why do they make Yagis with flat elements? They could use inverted Vís if they desired. But flat dipole elements are the best performers over ground, thatís why.

BTW, slopers are possibly the worst use of a dipole for DX work. They radiate off the sides better than in the direction of the slope. Surprise, surpriseÖ thatís how dipoles are supposed to radiate Ė broadside.  Slopers were a big thing in the 80ís on 75M before the DXers wised up and went back to high dipoles or Yagis.

OK, I realize we are splitting hairs here and the guy looking for advice will probably end up with some wire hung in the trees somehow, but thatís no reason not to teach him the best method first. Maybe he had the perfect supports to put up a flat dipole, maybe not.  If we have to use inv v, or inverted Uís or whatever to get a dipole in the air, so be it.  But to tell the guy that striving to make a dipole flat is pointless and counter-productive (and hogwash) is ridiculous.

Tom, K1JJ




Title: Re: vertical antennas
Post by: W2DU on May 28, 2011, 05:00:14 PM
Amen to your rebuttal, Tom.

Walt


Title: Re: vertical antennas
Post by: K5UJ on May 28, 2011, 05:06:16 PM
<<<Another popular approach to 160/80/40 is a full wave loop for the lowest band. feed with balanced line.   Whatever shape the available supports allow will work, but the closer to round the better.  I haven't tried one of these but a lot of hams swear by them.  Most people I've heard using one of these have them at 30 to 50 feet.>>

Then you should try one.  I have.  Loops suck unless you can get them way high, higher than most hams are able to do.   If you have four or more really tall trees, as in over 100 feet, then go for it.  Lower down on 75 there is too much wavelength exposure and ground loss through coupling to earth and on 160?  Fugeddabodit, unless you can get the loop up around 150-200 feet on that band.  

Somewhere on one of his pages, Cebik said small and high (high dipole) beats big and low (loop at 30 or 40 feet) any day of the week.   Don't make the mistake of thinking that because of its size, a loop is a great performer.  Height is everything.  Height directly = dBs and is really the only legal way to get a lot of them but, height is expensive.   Therefore, if you can only afford one or two 50 foot supports, you are far better off going with a dipole than several short poles holding a loop.  

On a dipole it is okay to let the ends dangle down if you have to.  But, there is a big difference between the ends hanging and an inverted V.  I have a 130 foot dipole on my 100 x 50 foot lot with 20' on each end hanging down (dipole is at 50').   I  don't have the big signal I'd like to have (few of us do) but I can usually make contacts and it is much better than the 1 w. loop I had on 75 at 25 to 30 feet before.   You will be amazed at what a simple high dipole can do.   Most of the big AM signals on 75 are from guys who have nothing more than dipoles up around 100 feet or more.   If you didn't know you'd swear they were running 2 kw broadcast rigs.  But they are often running no more than 300 w., sometimes much less.   Antenna is everything.


Title: Re: vertical antennas
Post by: N8LGU on May 28, 2011, 08:25:45 PM
    I had to cut down my skyhook 90' pine tree. That left me with nothing to support a high dipole/inverted "V" for 80M. In desperation I installed a Hustler 5BTV with a tilt base and radial plate from DX Engineering. Also pinned 40 25' radial to the grass.
    Result: If I can hear 'em, I can work 'em. And I can hear a lot.
No it's probably not as good as a dipole overall, but in some ways it's probably better. It does have some downsides: Expensive. Labor intensive. Has to be precisely tuned. No wiggle room on 80M.http://amfone.net/Amforum/index.php?topic=27315.msg208313#msg208313


Title: Re: vertical antennas
Post by: KM1H on May 28, 2011, 08:59:02 PM
Verticals work fine over poor ground if you use elevated radials. My 160 and 80M DX results from this hilltop rock pile speak for themselves.

Verticals on high ground got a bad rap in the early days of AM BCB because the poor ground and on ground radials destroyed the surface wave part of the lobe. It took over 75 years for the FCC to get away from their 1920's mind set and authorize elevated radials.

Carl


Title: Re: vertical antennas
Post by: KX5JT on May 28, 2011, 09:07:04 PM
I agree with Carl.  I put up a Zero Five elevated ground plane for 40 through 10 a couple months ago.  It's doing FB on those bands with my tuner.  15 meter AM into Europe and all over the world in other modes much easier than my inv vees.

(http://i271.photobucket.com/albums/jj131/kx5jt/05gp.jpg)


Title: Re: vertical antennas
Post by: ve6pg on May 29, 2011, 10:11:55 AM
..what's a "zero five" ?....never heard of it...

..sk..


Title: Re: vertical antennas
Post by: KX5JT on May 29, 2011, 10:45:23 AM
..what's a "zero five" ?....never heard of it...

..sk..

http://www.zerofive-antennas.com/ (http://www.zerofive-antennas.com/)

I build my own wire antennas, but I couldn't build an aluminum tubing vertical as good as Tom @ Zero Five. 

The version I have uses a 26 foot radiator and 6 ridged aluminum radials 100 inches long.  The radials are above my roof line.  It's designed to work with a wide range tuner via a 5kw matching transformer for 40 through 10 meters.  It works better than anything I had up for the higher bands.  I wanted a simple elegant antenna since we are heading towards a peak in the cycle.  Beams and rotors are beyond my present finances.

I still use my 80/40 meter parallel inv vee for 80/40 "local" work.


Title: Re: vertical antennas
Post by: ve6pg on May 29, 2011, 11:00:40 AM
..ok john...i had a cushcraft r-7 yrs ago..it had some kind of matching box near the base...40-10, but it sucked...had to guy it with poly rope as well...i was very disappointed with it...as i understand, you werk nights, or operate in the wee hours on the morning...i'm likely going on a 3-11pm shift (eastern time) in the next month....what time/where do you operate mostly?..

..tim..

..sk..


Title: Re: vertical antennas
Post by: K1JJ on May 29, 2011, 11:01:00 AM
Verticals are cool antennas to look at. Must be the old AM broadcash influence in us... ;)

Yes, as we all know, the ground plane, whether it be in the form of a car, ground radials or elevated radials is the key to vertical performance.  I suppose we could say that otherwise, a vertical is a vertical is a vertical. The difference being the loss in traps or of a severely shortened vertical. Though, W2FMT? showed us that shorties on 40M with big capacitance hats did quite well for efficiency.

Many of the guys (including the previous posts) report outstanding results on 40M and higher with verticals.  160M and 75M DXing works well too. Though, the anomaly appears to be when using a vertical for "local" AM work on 75M. Out to maybe ~300 miles, in general, I've never seen a vertical stronger than a dipole. This 300 mile range on 75M is of utmost importance to AMers, at least on the east coast. The high angle radiation can be down as much as 20db compared to a dipole.

Farther away, W9AD has proven how well verticals work on 75M using his phased array of Hygain? towers.

What I'd really like to see is someone try a 4-square of verticals, even 1/8 wave whips, on the higher bands, put out in a clear field away from everything. There are a few phasing boxes available (Comtech and DX Engr?) that are plug and play. The ability to see f-b, forward gain and directional changes with those low angles when using a good ground plane would be quite versatile. I still think a high Yagi would be hard to beat, but a 4-square could be installed with much less cost and effort, depending on the ground system used.

I agree that the Earth soil plays an important part into how elaborate the radial system needs to be. The elevated radial debate has been interesting over the years.

Chris, AJ1G, was talking in another thread about yesterday driving his car mobile out on Stonington Point, CT (next to the ocean) and using 5 watts  20M CW to work Europeans easily. It wud be an interesting experiment to see the difference when he drove inland 10 miles and tried the same thing.

T


Title: Re: vertical antennas
Post by: k4kyv on May 29, 2011, 01:09:24 PM
What is the alleged magic about the 43' vertical on 160? ???  I hear a lot of people, even those with plenty of space to erect something taller, report that's what they are using. Some operate with a good radial system and some without.  Obviously, performance will be much improved with the good ground system, but so would increasing the height to at least 1/8λ, approximately  65'.  Even with top loading and a good radial system, as the vertical length is decreased below 1/8λ, radiation efficiency drops off rapidly.

43' on 160 would be equivalent to 10'9" on 40m, barely more than an 8' mobile whip.


Title: Re: vertical antennas
Post by: KX5JT on May 29, 2011, 02:09:31 PM
"i'm likely going on a 3-11pm shift (eastern time) in the next month....what time/where do you operate mostly?."

Tim, It isn't easy finding AM activity during dark hours in Summer.   75m (no antenna on 160) noise floor is 20 to 30 over S9 where most AM signals are... (except maybe Don KYV or Brandon IIA) into my location.  Makes it difficult copy.  On 40 I do play on 7290 and call CQ a lot to no avail between midnight and dawn.  Sometimes on 7.160 but there are a lot of VK's and ZL's around there on sideband, so I often don't bother firing up AM.  

The way my job works is I get 3 nights off in a row so I am occasionally up in the early afternoons, but not too often.  When I am I could be anywhere between 40 and 6 meters on the usual AM frequencies for each band.  

The best success I've had running AM in the early mornings (dark hours) during static season is with scheds.  Paul VJB and I hooked up one morning, that was fun.  

"What is the alleged magic about the 43' vertical on 160? "

From http://www.hamradio.me/antennas/answer-to-everything-43-feet-antenna.html (http://www.hamradio.me/antennas/answer-to-everything-43-feet-antenna.html)

The peak radiation angles and relative antenna gain for each bands are:

    ~ 5 dBi @ 57√ā¬į for 10 meters Ė impressive, but high angle
    ~ 4 dbi @ 37√ā¬į for 15 meters
    ~ 1 dBi @ 16√ā¬į for 20 meters Ė nice low angle
    ~ 0 dBi @ 25√ā¬į for 40 meters
    ~ -2 dBi @ 29√ā¬į for 80 meters Ė this is quite functional
    ~ -8 dBi @ 23√ā¬į for 160 meters Ė lossy, but it does work

Several things are apparent:

    The antenna has ďbetter than nothing at allĒ performance on 160 meters and is certainly interesting for this difficult band.....................


I think the stats there and that last statement says it all.  It will load up and put out a signal on 160 but it is certainly a compromise there.   Don, the fact that you actually hear people using them proves it does do this, but pretty poorly.  My elevated ground plane (26 ft radiator) actually loads on 80 m and puts out a signal a bit poorer than my low inv vee.  If I had no 80 m antenna, I could use it and make contacts.  Maybe come winter, It will do better for real long distances, but I doubt it.  I'll do A/B comparisons then.


Title: Re: vertical antennas
Post by: K1JJ on May 29, 2011, 03:32:21 PM
Interesting stats, John - tnx for posting them!

What stands out is the "gain" on 10-15M is in the higher angles. 20M is perfect at 16 degrees however. Ever hear someone say, "Boy, I sure would like to fly a 400' high balloon wire as a vertical on 75M."   Your stats are a good example showing how the pattern gets moved into the higher angles just like a 160M Zepp acts on 20M... the desirable Ĺ wave pattern goes to heck.

The optimum angle on 20M for east coast to Europe is around 15-20  degrees take-off or so. On 15M it's about 10 degrees and on 10M about 5-7 degrees. This all varies with sunspots and conditions, of course, but studies have shown on average, a Yagi stack designed for these angles works well overall.

So, there is a reason to use a 1/4 wave or 1/2 wave long vertical on the band of interest. That's when the angle is lowest  - and also the IR efficiency is higher compared to a shortie version.

Another thang to consider is, "Can my location SUPPORT" a low angle of take-off?"   If you do the geometry, to support a 15 degree vector angle coming off an antenna, it takes quite a distance on the lower bands. On the higher bands, it still means the area around the antenna must be clear of major obstructions like houses, power lines, etc to be optimum. If the lobe needs to go thru a close-by house, the plumbing, wiring, etc may make it down many db compared to the higher angle lobes that clear the house.

The word, "optimum" is the key. Installations will still work, but not as well when radiation has to propagate thru structures to cover the lower angles. RFI is another symptom of low angles in neighborhoods.

Also, especially for horizontal DXing antennas, can the locationís EARTH soil support the lowest angles 1000ís of feet away?  Radials will not help these very low angles when they attempt to reflect off the ground and reinforce the main lobe.

Verticals are very demanding systems and jealously guard their territory. The best installation is to mount them out in a clear field with nothing for a mile around. But few of us can pull this off.  Here, I not only have tower obstructions, but my Earth soil is rocky and poor. High horizontals are all I can work withÖ sigh.  I would love to try a 4-square  or even 8-square on  40M and 10M, but the results on the other bands was poor.

The exception was a 3-vertical phased system I built for 160M using about 15,000í of radials. That vertical system took out a dipole at 190í into Europe by 10db. Verticals indeed work well on 160M if they have big radial fields to work with. Plus the optimum angle on 160M for Europe is MUCH higher, like maybe 25-30 degree or higher.  BUT, the wavelength distance is longer, so we still need a minimum of obstructions to clear even a 30 degree takeoff angle.

No free lunches or everyone would be doing it alreadyÖ  ;D

T


Title: Re: vertical antennas
Post by: ve6pg on May 29, 2011, 03:50:12 PM
..ok john..i'll let you know how my shift is gonna werk out. i shud be home about mid-nite,(eastern), or so when i go on this shift. i'm not one to go to bed when i get home, hell, it's like going to bed at 4 in the afternoon for the day-lighters...40 might be a good go...whatcha think?..we shud keep in touch on this...
..tim..

..sk..


Title: Re: vertical antennas
Post by: K5UJ on May 29, 2011, 11:36:00 PM
What you almost never hear or read anyone say or write when it comes to using a vertical, is that they almost always tank big time on receive.
On 75 m. it's just about impossible to operate at night with my vertical (which is the only good time to use one since they are a low angle skywave antenna above 160 m.) if I have to use it as my rx antenna.   Only way I can use it is with my small tuned 75 m. rx loop.   On the high bands, they take a dump on rx as well--I'm not sure why, maybe the S/N ratio up there also, as I have never been able to hear well with one.  

Maybe out in the sticks they are okay on receive but mine always picked up too much noise and even on a quiet high band, a balanced horizontal antenna like a dipole snagged the signals much better.   I have gotten by on 160 with the inverted L on tx and rx but there, the 160 m. tuned rx loop is often a QSO saver.

What is the alleged magic about the 43' vertical on 160? ???  

They magically suck in wads of cash from people with boatloads of $$$ and thimbles of antenna knowledge.  


Title: Re: vertical antennas
Post by: W4AAB on May 29, 2011, 11:57:29 PM
The 43 feet is a 5/8 wave antenna on 20m. I don't know why anyone would claim that it could be very efficient on any band lower in frequency. The same logic was used with the G5RV. It was not intended as a multi-band antenna. It is a gain antenna on 20m only.


Title: Re: vertical antennas
Post by: k4kyv on May 30, 2011, 11:50:45 AM
The problem with using a vertical for receive is caused by the same characteristic that makes it a good DX antenna for TX and a good AM broadcast transmitting antenna.  At certain lengths it is predominately a low angle radiator - good for DX.  But it also responds well to ground wave, which is inherently vertically polarised.  Much, if not most, local electrical noise propagates by ground wave, so a vertical is an extraordinarily efficient receiving antenna for electromagnetic smog.  Much of the time I can't receive worth a hoot with my 127' vertical on 160.  The dipole, beverage or indoor loop usually work better for RX. When transmitting with a vertical, you really do need a separate receiving antenna.


Title: Re: vertical antennas
Post by: K1JJ on May 30, 2011, 12:37:07 PM
Much of the time I can't receive worth a hoot with my 127' vertical on 160.  The dipole, beverage or indoor loop usually work better for RX. When transmitting with a vertical, you really do need a separate receiving antenna.

Yep.

Almost without exception, the big gun 160M DXers use a beverage for receiving and a vertical for transmitting. It's almost a given up there.

It works that way on 75M and 40M too, but to a diminishing degree.  Maybe that's because the average noise level drops until there is virtually none on 20M and higher.  Ie, many guys use their verticals for receiving above 160M.

I notice the DXer guys with the 4-squares on 75M sometimes complain that the noise is killing them, but their bevs are fine. Then other nights they listen better on the verticals. Much must depend not only on local noise, but propagated noise via the ionosphere and their antenna's directivity abilities.

I notice on certain nights the f-b of the 75M high loops will enable me to hear Europe thru the USA western storms to the back.  That extra couple of S units gives quite a receiving edge some nights when many guys throw in the towel.     F-B is a good thang when needed..

T


Title: Re: vertical antennas
Post by: k4kyv on May 30, 2011, 01:40:45 PM
There is no guarantee that the beverage will be noise free. It, also, responds predominantly to vertically polarised signals.  It kills the noise by virtue of its horizontal selectivity - only selected sectors of the 360į pie are received, cutting out a lot of the noise that would be picked up by an omnidirectional vertical.  If the noise source happens to be in the same direction as the bore-sight of the beverage, you are SOL. I have that problem here. A road about a half-mile from here has noisy power lines on both sides, and a major intersection with another road with noisy power lines is right in line with New England and Europe from here, where my terminated beverage is aimed. Whenever any one of those power lines acts up, the beverage is useless.

The same is true for the K9AY, flag, pennant, EWE and similar "low noise" antennas.  They are essentially phased short verticals with a cardioid pattern. The trick is to get the null in the cardioid to point towards the noise source. A rotatable arrangement is most effective.

I carefully built a K6STI loop (http://www.angelfire.com/md/k3ky/page45.html), but found it worthless. It was no more low-noise than a piece of wire tossed out the window and connected to the antenna terminal of the receiver.


Title: Re: vertical antennas
Post by: K5UJ on May 30, 2011, 10:04:19 PM
I wondered about that K6STI antenna and had planned to make one.  I got some of the parts to build the tuning network for it but never got around to it.   Now I have in the back of my mind a plan to make a pair of ferrite loopstick antennas for 160 that can be rotated.  I'd put them inside some cover like a PVC pipe and mount them a few feet off the ground, separated by 40 or 50 feet.  Each would have a preamp and they would feed my phase shifting nulling noise network.  First they would be rotated to null one point source then the noise canceling network would shift noise picked up on one, 90 degrees to null it with the signal from the other loopstick.  Two noises eliminated.   I can get the ferrite rod from Amidon.  I know a guy a few miles away from me who did something similar with a single loop stick to aid him in operating 160 CW.  I have his plans.  He built a single one in a PVC pipe with the preamp in the pipe getting DC via the coax feedine.  He had to null out some kind of line noise and he simply laid his on the ground and oriented it to null the noise and he said even on the ground it worked as a rx antenna (but he doesn't chase DX).   Anyway, the problems for me are that the costs of the materials and rotators start to add up but worse is finding the free time to set it all up. 


Title: Re: vertical antennas
Post by: G3UUR on May 31, 2011, 09:26:33 AM
Guys,

Iíve been watching this thread from the beginning and since Tom appeared to be doing a great job of advising AE1CT, I didnít jump in and help. It was a great shame that it later turned into a pissing contest between a few ĎBig Gunsí because talk of 100ft high dipoles, elevated 80m ground-plane antennas and the like would have been of no help to AE1CT. In fact, it may have put him off amateur radio all together. I hope not, though, but the digression certainly didnít helped.

Heís already stated that he has limited real estate and no trees higher than 30ft. His desire is to operate 40, 80 and possibly 160m. It sounds as if heís in a typical suburban situation, and is probably surrounded by other houses all with a multitude of electrical appliances emitting digital broadband rubbish. Itís a hell of a situation to be in, but is typical of many amateur stations around the world. I operated from a similar situation for 7 years after getting my license. Youíre all the time reacting to new noise sources and experimenting with different receive antennas. It complicates things enormously because in the early years after getting your license youíre normally trying to find the best transmitting antenna for your local situation anyway.

My antenna experience is limited to amateur radio, but having been in some difficult situations over the years I have experimented with antennas that are near to the ground and checked out all sorts of different configurations. Iíve also tried to learn what I can from others by reading books on EM theory and antennas. I donít read books written by other amateurs, even if they are professionally involved in antenna work, but restrict my reading to the classic texts which I know I can trust. Thereís too much mythology in amateur radio to trust books written by amateurs, though these books are often good for getting ideas about something out of the ordinary, which might just work well in your situation and enable you to put out a better signal.

So, let me tell you what Iíve found out over the years. If you want to operate 160m from a small plot, youíll have to try both a short doublet and a bent quarter-wave inverted-L to see which works best in your situation. It very much depends on who you want to work and how far away they are. Itís too complicated to model and you could never do it realistically anyway, even if you could model the ground accurately enough, because of other obstacles, such a trees, shrubs and buildings with electrical wiring. The inverted-L antenna requires a good ground system to be effective and you might want to try the short doublet first because thatís easier to install. A major source of ground loss on 80 and 160 is E-field coupling to the ground beneath the antenna. Short doublets operate with a much higher E field than full-sized ones, so this ground loss can be a killer for low, short dipoles or doublets. This is one reason why the ends of low dipoles or doublets should not be bent downwards. Itís fine to bend the last 20 or 30ft down towards the ground if your antenna is at 100ft, but if itís at 30ft high and you bend the last 20ft down towards the ground the extra loss reflected into the antenna can lose you more than 6dB. The exact amount depends on both the dielectric constant and conductivity of the ground beneath your antenna. The radiation resistance also drops a bit when you bend an antenna, so this doesnít help the efficiency either. If you have to bend an antenna to fit it into a small plot, make the bends in the horizontal plane and keep the ends up as high as you can.   

The end-loading of short dipoles doesnít reduce interaction with the ground much but it does raise the radiation resistance by up to 4 times. This improves the radiated signal by up to 6dB. Linear end-loading is preferable to inductive loading because it doesnít reduce the bandwidth as much. Linear end-loading can very often be invisible in trees, whereas end-loading coils add weight to a run of wire and are also more visible. If you have any handy trees where you can terminate a dipole leg, you can run the linear loading wires up and down between branches to use up the extra length.

Reinartz loops are a great antenna for small plots, and although the radiation resistance is only about 15 ohms at the feed point, the fact that the ends are close together reduces ground loss when they are very low in height. A Reinartz loop is just a half-wave dipole bent into a square with the ends close together, but not connected. This not only reduces ground loss, but also reduces electrical pick-up to some extent. Both ends of a Reinartz loop on 80m could be loaded for 160m using linear loading sections for each end in the same tree, but you might want to add 80m traps so you donít spoil the performance on 80m when you add the 160m linear loading section.

If you can manage to fit in an 80m full-wave loop fed with open-wire feeders, you can load this up on all bands, including 160m, though you would probably get better performance on 14MHz and above from a dipole for one of the bands at 30ft. Iíve never found multi-band wires, doublets or loops to work as well as theory predicts on the higher bands and have always used a separate antenna for 20 thru 10m. One word of warning about loops though. Generally, balanced antennas do not pick up interference as badly as unbalanced antennas, and balanced full-wave loops pick up less than balanced doublets or dipoles because they are closed loops. However, if in the process of putting up a full-wave loop, the extra run of wire takes your antenna closer to a dominant noise source, then it could be worse than a balanced doublet or dipole.

If you try a balanced antenna first, you can assess your local noise situation and see whether you can get away with using the antenna successfully for both receive and transmit. If you canít and have to use a separate receive antenna, you might want to leave the balanced antenna up for a season and see how it performs over a period of time. Next year you might consider trying an inverted-L for transmit and a small magnetic loop, EWE or K9AY on receive. The inverted-L will need a good earth system to work well and that will require a lot of effort. However, it has a big advantage over a straight vertical because it produces high-angle radiation as well as low angle, and youíll find that a great advantage for working stations closer than 250 to 300 miles on skywave. Youíll already have read about some of the noise problems associated with ground-mounted verticals, but besides that restricting all your radiation to ground wave and low angle in a suburban situation can be disastrous if youíre hemmed in by other buildings and a lot of your transmitted signal is absorbed locally. Elevated verticals with a separate ground plane are a different story, but in your situation they appear not to be a possibility.

Sorry about the length of my posting, AE1CT, but I hope some of this helps you decide what you need to do.

Dave.


Title: Re: vertical antennas
Post by: flintstone mop on May 31, 2011, 10:56:54 AM
What is the alleged magic about the 43' vertical on 160? ???  I hear a lot of people, even those with plenty of space to erect something taller, report that's what they are using. Some operate with a good radial system and some without.  Obviously, performance will be much improved with the good ground system, but so would increasing the height to at least 1/8λ, approximately  65'.  Even with top loading and a good radial system, as the vertical length is decreased below 1/8λ, radiation efficiency drops off rapidly.

43' on 160 would be equivalent to 10'9" on 40m, barely more than an 8' mobile whip.
Hey Don
There is no free ride with a 43 footer. It needs a "loading wire" like an L and the unun included usually will not work either. The 'manufacturers' even say to use a certain type of coax with a certain velocity factor and 150 feet....so the magic is gone. You pay $300 for a 43 foot mast to really make an L antenna.
For the urban guy and small lot a dipole crammed in the space allotted is all he can do. Open  ladder line and a JJ tuner gets the dipole to other bands. "The SLAB Bacon" KB2AHE,  has had wonderful success with his shortened dipole even on 160M....Somewhere on this site Frank 'The Slab Bacon" posted info on his shortened dipole and how he made it work so well. If you follow his method it will work for you too.
Fred


Title: Re: vertical antennas
Post by: Sam KS2AM on May 31, 2011, 11:19:21 AM
i dont have very tall trees in my yard (30 ft) high and the most room i have is probably 40 meters and i want to get on 80. i want to operate mosty sw from my location and there are no trees that will give me that direction. i want to get on the air but im in a position were i dont have a big yard or the tree hight that i need. WHATS a future AMer to do. any ideas would be greatly helpful.

Hello Gary.  Theres a new book, "ARRL's Small Antennas for Small Spaces". I have not read it but the description sounds encouraging and it may help you with ideas that will fit your property and your goals.

http://www.arrl.org/shop/ARRL-s-Small-Antennas-for-Small-Spaces/ (http://www.arrl.org/shop/ARRL-s-Small-Antennas-for-Small-Spaces/)

(http://www.arrl.org/shop/images/P/8393.jpg)


Title: Re: vertical antennas
Post by: Steve - K4HX on May 31, 2011, 03:39:31 PM
http://amfone.net/Amforum/index.php?topic=24242.msg179317#msg179317


Title: Re: vertical antennas
Post by: k4kyv on May 31, 2011, 05:08:58 PM
Linear end-loading is preferable to inductive loading because it doesnít reduce the bandwidth as much.

Also true for inductive or capacitive feed line loading to electrically lengthen or shorten the feed line so that the feed point at the transmitter end presents a voltage or current loop at the tuner. That's why I use the "tennis net" (60' of feed line folded back on itself, switched in between the tuner and the feed line going up the tower, when I use the 80m dipole on 160, instead of simply inserting a couple of capacitors or coils in series with the feeders.

I once used an inverted-L, 130 ft. long, 65 ft. vertical and 65 more feet horizontal.  The ground plane consisted of 30 quarter-wave radials. When a storm took down both masts, I was able to salvage enough material to re-erect one mast, 65' tall, without the horizontal section. The resulting 1/8λ vertical performed about the same as the 1/4λ inverted-L.  I don't recall the difference in bandwidth, but at the time, we were limited here to only a couple of 25 kc/s slots of band, 1800-1825 and 1875-1900, so bandwidth wasn't so much an issue.


Title: Re: vertical antennas
Post by: G3UUR on June 01, 2011, 06:07:09 AM
Don,

I donít know the height of the 80m dipole you use on 160m, but I suspect itís quite a lot higher than 30ft. Ground loss reflected into the antenna at 60ft, or more, is probably low enough that you donít notice any difference, but at lower heights as the radiation resistance drops and the ground loss increases the situation changes dramatically. Switching in extra feed line doesnít alter the antenna at all, and at low heights improving the efficiency of the antenna is crucial to getting reasonably good results. My previous point was that you need some sort of end loading to increase the radiation resistance to improve the efficiency, and linear loading is the better option because the characteristic impedance of the extra section is lower and it introduces much less inductance into the antenna. This lowers the Q of the antenna and improves the bandwidth because the radiation resistance is higher and also the effective inductance of the series-resonant circuit formed by the antenna is much lower than it would be for inductive loading. Raising the radiation resistance is the primary goal and the bandwidth improvement is a secondary issue, though pretty useful to have.

Regarding your comments about the comparison between a 65ft high, 130ft long inverted-L and a 65ft vertical; are you suggesting AE1CT should use a vertical on 160m?  The purpose of this last part of your posting is not clear. Are you trying to convince him not to use the inverted-L type? Iíve done tests on 160m between a 32ft base-loaded vertical and 132ft inverted-L with 32ft of vertical using the same modest ground system from a small plot and the inverted-L wins by nearly 10dB on ground wave alone. When it comes to high-angle stuff there is just no comparison. Noise pick-up is also a problem with verticals, and I found that using a balanced doublet which could also be used with the feeders strapped for local ground-wave working on 160m was the best all-round compromise antenna in a small plot. It could be used balanced for receive even when transmitting with the feeders strapped, if needed.

Given the fact that any vertical installation needs to be out in the clear, have a reasonably extensive ground system and be at least one-twelfth of a wavelength high to work moderately well, Iíd have thought that it would be a poor choice for AE1CT in his restricted circumstances because even if he put lots of effort into the ground system it wouldnít be very extensive and heíd still be limited by other factors outside his control. Also, heíd have a skip zone between the limit of his ground-wave range and where his low-angle signals return to earth. There may be lots of stations he wants to work in this zone around New England. I may be wrong, but Iíd have thought he needed some high-angle radiation as well.

Dave.


Title: Re: vertical antennas
Post by: AJ1G on June 01, 2011, 07:44:13 AM
Chris, AJ1G, was talking in another thread about yesterday driving his car mobile out on Stonington Point, CT (next to the ocean) and using 5 watts  20M CW to work Europeans easily. It wud be an interesting experiment to see the difference when he drove inland 10 miles and tried the same thing......

Tom  - you can up that to New Zealand (ZL2AGY)with 5 watts on 40 CW !  Did that the other morning bout 0630 EDT with the K1 and the hamstick clone on the Volvo...

I dont really need to go more than a half mile up the point inland before the signals drop off a lot relative to being on the Point.  A lot of that probably has to do with local absorbtion by buildings though.


Title: Re: vertical antennas
Post by: flintstone mop on June 01, 2011, 08:38:16 AM
Chris, AJ1G, was talking in another thread about yesterday driving his car mobile out on Stonington Point, CT (next to the ocean) and using 5 watts  20M CW to work Europeans easily. It wud be an interesting experiment to see the difference when he drove inland 10 miles and tried the same thing......

Tom  - you can up that to New Zealand (ZL2AGY)with 5 watts on 40 CW !  Did that the other morning bout 0630 EDT with the K1 and the hamstick clone on the Volvo...

I dont really need to go more than a half mile up the point inland before the signals drop off a lot relative to being on the Point.  A lot of that probably has to do with local absorbtion by buildings though.

Definitely makes sense when using 20M. Everything gets almost cookie cutter simple from about 40M on up.
80M on down there are certain criteria that cannot be avoided. Antenna efficiency, wavelengths, dipole height above ground, ground losses.
I hope the OP is not totally cornfused............but antennas are our favorite subject....hi
Keep the dipole at the top of your plans. As high as you can get it. As long as you can fit it in your property, even if it zigs or zags a little and feed it with ladderline and build a good tuner.

Fred


Title: Re: vertical antennas
Post by: k4kyv on June 01, 2011, 01:13:05 PM
I donít know the height of the 80m dipole you use on 160m, but I suspect itís quite a lot higher than 30ft. Ground loss reflected into the antenna at 60ft, or more, is probably low enough that you donít notice any difference, but at lower heights as the radiation resistance drops and the ground loss increases the situation changes dramatically. Switching in extra feed line doesnít alter the antenna at all, and at low heights improving the efficiency of the antenna is crucial to getting reasonably good results.

You are correct.  My 135' long 80m dipole is close to 1/4λ high, at 119' at the apex, drooping to about 100' at each end. That was my only top band antenna after I first put up the tower, before I installed the radials.  I didn't even bother to try feeding the tower as a vertical without a radial system.  I think the height of the antenna makes up for the shortness of it; I can get fair results all over N America with it although the vertical tends to be superior at greater distances, and it is far better than the vertical within the skip zone.  For instance, in Nashville, which is about 50 miles away as the crow flies, the 80m dipole comes in up to 30 dB stronger than does the vertical, sometimes making the difference between a full quieting carrier, and a signal buried in local urban electrical noise although still readable.

Since each leg of the dipole is 1/8λ on 160, and the length of the open wire tuned feeders up the tower is 1/4λ, the total length of feed line plus dipole leg is 3/8λ - making the feed point at the bottom end of the feeders precisely midway between a voltage loop and a current loop. My first attempt to feed it was using a balanced link  coupled tuner at the base of the tower, parallel tuned, with the feeders tapped down on the coil.  I was able to get a 1:1 match with the transmission line from the shack, but using a split-stator capacitor with 3/16" spacing (rated at 7 kv), I couldn't modulate 100% at more than 100 watts before the capacitor arced over. Apparently, the tuner couldn't handle the highly reactive load very well. So I tried adding an additional 60' to the feeders, making the total feeders + dipole leg = 1/2λ, I was able to feed the open wire line directly with parallel tuning, get a perfect match, and modulate as much RF as I could generate well beyond 100% on positive peaks, with no sign of arc-over.

Not surprisingly, this set-up is extremely sharp tuning.  I cannot move much more than Ī 5 kc/s without having to re-adjust the tuner. Originally, it was like being crystal controlled, since the tuner is at the base of the tower, about 140' away from the shack, so I ended up driving the tuning capacitor remotely from  the shack using a reversible motor and worm drive.  My point about bandwidth was that I could have tuned out the reactance at the OWL feed point by using a lumped value reactance (coil or capacitor) in series with each feeder, but (according to my intuitive reasoning, which may not be correct) I was afraid the tuning would have become even sharper, and not only would the split stator capacitor in the tuned circuit have to be re-adjusted with changes in frequency, so would the series capacitors or inductors. The equivalent series loading inductance in the form of the additional length of feed line, automatically varies to some extent as the frequency varies, but a lumped value inductance using a set of fixed coils would have to be manually adjusted with changes in frequency to maintain the best efficiency with the tuner, whie minimising the amount of reactance the tuner must compensate for.

Maybe my seat-of-the-trousers intuition is wrong, so I would be interested in other opinions: would a pair of fixed inductors each inserted in series with one of the balanced feeders work as well, with as wide a frequency range and as wide a bandwidth per setting, without incremental adjustment of the series L as the frequency is changed, as does my solution of merely inserting the additional 60' of feed line leaving the resonating capacitor in the ATU as the only variable adjustment?

Quote
My previous point was that you need some sort of end loading to increase the radiation resistance to improve the efficiency, and linear loading is the better option because the characteristic impedance of the extra section is lower and it introduces much less inductance into the antenna. This lowers the Q of the antenna and improves the bandwidth because the radiation resistance is higher and also the effective inductance of the series-resonant circuit formed by the antenna is much lower than it would be for inductive loading. Raising the radiation resistance is the primary goal and the bandwidth improvement is a secondary issue, though pretty useful to have.

Agreed. My additional section of resonant feeder would have no effect on radiation resistance or efficiency of the antenna. But as I thought up the idea while designing the antenna configuration way back in 1981, a nearly identical train of logic occurred to me as what you stated (above, in bold), although I never bothered to go through all the tedious calculations with various possible examples taking a set of frequencies across the entire band using both approaches, and comparing the results. I just tried out the added feeder section, it worked well, so I configured it to make the additional feed line length automatically switch in with the coil, and have thought little more of it since.

Quote
Regarding your comments about the comparison between a 65ft high, 130ft long inverted-L and a 65ft vertical; are you suggesting AE1CT should use a vertical on 160m?  The purpose of this last part of your posting is not clear. Are you trying to convince him not to use the inverted-L type?

No, I suppose I didn't make myself perfectly clear on that point. I was merely pointing out my own experience with the above described antenna. I think in AE1CT's case, the inverted-L would be the better choice, since the radiation resistance of a 32 ft vertical (approximately 1/16λ) would be very low and the antenna would be extremely inefficient without an extensive radial ground plane, and even with that, tuner loss would still be substantial. In my case, the vertical section was 1/8λ, so the radiation resistance should have been something on the order of 12Ω, which my radial system and tuning unit appeared to handle well. I wasn't able to make A-B comparisons of the L vs the vertical of course, but signal  reports always seemed about the same. Still, for 160m, 32 ft. is not much height for a horizontal radiator, but the additional top loading should make the vertical section radiate better than it would as a mere vertical standing alone.  At 32' on 160, this would be the exact equivalent of using the standard 8' mobile whip on 40m.


Quote
Iíve done tests on 160m between a 32ft base-loaded vertical and 132ft inverted-L with 32ft of vertical using the same modest ground system from a small plot and the inverted-L wins by nearly 10dB on ground wave alone. When it comes to high-angle stuff there is just no comparison. Noise pick-up is also a problem with verticals, and I found that using a balanced doublet which could also be used with the feeders strapped for local ground-wave working on 160m was the best all-round compromise antenna in a small plot. It could be used balanced for receive even when transmitting with the feeders strapped, if needed.

Given the fact that any vertical installation needs to be out in the clear, have a reasonably extensive ground system and be at least one-twelfth of a wavelength high to work moderately well, Iíd have thought that it would be a poor choice for AE1CT in his restricted circumstances because even if he put lots of effort into the ground system it wouldnít be very extensive and heíd still be limited by other factors outside his control. Also, heíd have a skip zone between the limit of his ground-wave range and where his low-angle signals return to earth. There may be lots of stations he wants to work in this zone around New England. I may be wrong, but Iíd have thought he needed some high-angle radiation as well.

Too right. The horizontal section would radiate some high-angle, making it work fairly well in the local area once skywave propagation opens up in the evening. I found it interesting in the series of articles published a year or two ago in QEX, that both using modelling and experimental results, the author found that with a smaller number of  radials, for example 8 or less, the efficiency was actually better when the radials were kept short (less than 1/8λ) than when they were extended out to a full 1/4λ.  He attributes that phenomenon to resonance effects of the quarter-wave length. OTOH, once a large number of radials is installed, the efficiency improves with additional length.

73,

Don




Title: Re: vertical antennas
Post by: G3UUR on June 01, 2011, 03:38:49 PM
Don,

Iím glad weíve got that sorted out because I wouldnít want Gary (AE1CT) to be left in any doubt about what the consequences of choosing one antenna type over another are going to be. To my mind there is one obvious one to try initially, and thatís the doublet with linear end-loading, but in restricted locations youíve just got to try everything to see what works best in that situation. Sometimes what seems to work best defies logic and explanation; but thatís the great thing about amateur radio Ė the serendipity factor!

I donít subscribe to QEX, so I missed the article you mentioned. However, Iím not surprised that fewer radials work better if theyíre shorter. The dielectric constant of the various types of soil and rock varies by nearly a factor of 10, but if you take an average value youíd expect a radial buried deep in soil to be about one-third the length that it is in free space for the same resonant frequency. The dielectric medium doesnít normally completely surround the radial for a significant distance in all directions, of course, because it usually isnít buried that deep, so it might need to be half the normal length for resonance in free space instead of one third. 

 You certainly have some set-up for 160 and 80m there. I donít know what power you run on 160m AM, but a tuning unit designed for use with anything up to a half-wave end-fed on 160 would probably be designed for a Q of 10 at 5kohm max. Your half-sized dipole on 160 would look more like about 40kohm resistive at the bottom of the 119ft feeder with an extra 60ft switched in circuit. Thatís still a pretty high impedance to match and any parallel tuner would be working overtime unless the inductance was incredibly large (335uH?). Iíd be inclined to ditch the extra 60ft loading section and try to match the rest with the simplest possible series arrangement and keep the Q as low as I can. Itís going to be around a 50, anyway, because the 12 ohms radiation resistance is going to drop to 6 halfway down the feeder, and then be transformed back up to 12 in series with +j600 at the bottom. You should be able to tune that with a pair of 350pF series variable capacitors in the feeder legs and match to 50 ohms with a shunt 2.35uH coil. That should give you an improvement in bandwidth.

Dave.


Title: Re: vertical antennas
Post by: KM1H on June 02, 2011, 09:46:30 AM
Quote
There is no guarantee that the beverage will be noise free. It, also, responds predominantly to vertically polarised signals.  It kills the noise by virtue of its horizontal selectivity - only selected sectors of the 360į pie are received, cutting out a lot of the noise that would be picked up by an omnidirectional vertical.  If the noise source happens to be in the same direction as the bore-sight of the beverage, you are SOL.

While a Beverage responds to vertically polarized signals they are predominantly skywave and not surface wave which is how local noise travels. If its aimed right at a close noise source then its a given it will pick up a lot.  Ground conductivity is a factor and here less is better; my RF ground is extremely poor, about 200 Ohms which seriously reduces groundwave pickup; even local BCB stations are relatively weak and dont bother 160.  Noise pickup here is gone in about a 1/4 mile, a recent local power outage gave me a chance to run the HRO-500 on a 12V battery and silence was complete even tho the houses over about 1/4 mile away still had power.

On 6M its completely different, I can pinpoint line noise 1-3 miles away.

Carl


Title: Re: vertical antennas
Post by: Steve - K4HX on June 02, 2011, 09:59:51 AM
Hereís an interesting article on radials and getting the most out of a given amount of wire. It predates the QEX articles.




I donít subscribe to QEX, so I missed the article you mentioned. However, Iím not surprised that fewer radials work better if theyíre shorter. The dielectric constant of the various types of soil and rock varies by nearly a factor of 10, but if you take an average value youíd expect a radial buried deep in soil to be about one-third the length that it is in free space for the same resonant frequency. The dielectric medium doesnít normally completely surround the radial for a significant distance in all directions, of course, because it usually isnít buried that deep, so it might need to be half the normal length for resonance in free space instead of one third.  



Title: Re: vertical antennas
Post by: k4kyv on June 02, 2011, 12:47:36 PM
You certainly have some set-up for 160 and 80m there. I donít know what power you run on 160m AM, but a tuning unit designed for use with anything up to a half-wave end-fed on 160 would probably be designed for a Q of 10 at 5kohm max. Your half-sized dipole on 160 would look more like about 40kohm resistive at the bottom of the 119ft feeder with an extra 60ft switched in circuit. Thatís still a pretty high impedance to match and any parallel tuner would be working overtime unless the inductance was incredibly large (335uH?). Iíd be inclined to ditch the extra 60ft loading section and try to match the rest with the simplest possible series arrangement and keep the Q as low as I can. Itís going to be around a 50, anyway, because the 12 ohms radiation resistance is going to drop to 6 halfway down the feeder, and then be transformed back up to 12 in series with +j600 at the bottom. You should be able to tune that with a pair of 350pF series variable capacitors in the feeder legs and match to 50 ohms with a shunt 2.35uH coil. That should give you an improvement in bandwidth.

I didn't take the trouble to calculate the inductance of the coil; it is the balanced tank coil I had on hand that came out of an old AM broadcast transmitter that used a push-pull final. It is resonated on 160m with a total of about 180 pf across the coil (300 pf/section split stator with 50 pf fixed vacuum in parallel with the whole thing). The link has 4 or 5 turns directly fed by the 50Ω transmission line, with no series or parallel capacitor. Matching is achieved using clips to trim the number of turns on the main coil at resonance; about 10% of each half of the coil is left unused at each end. The 440Ω OWL is parallel fed directly across the parallel tuned circuit. This set-up has been run up to about 800 watts carrier at 130+% positive peak modulation, and the variable capacitor, with 7 kv spacing, never arced over, and the rf voltages don't seem excessive. I might try your suggestion, and compare the bandwidths and efficiencies (DC input to rf amps in the feed line). I always figured that the sharp tuning indicated low loss in the system; at the low feed impedance and high SWR on the OWL, resistive losses in the system would lower the Q and broaden the tuning. Since this was originally a stop-gap measure for getting on 160m until I could get the ground radials laid, and it works well, I never analysed the circuit any further.

Looks like your suggestion uses series capacitors to electrically shorten the 3/8 λ total dipole leg+OWL length to a non-reactive current loop, excited by series-feed at the ATU.  Since the feedline loading capacitors and ATU series tuning capacitors are themselves in series, your 350 pf variables could be thought of as the composite of the series loading capacitances and the ATU series resonating capacitances, as the equivalent of two capacitances in series, kind of like a PI-network can be thought of as one L-network from the PA tube working into a second L-network that feeds the  load.

Steve, that is a good article on ground radials.  Thanks for posting the link. I wasn't aware that there were technical articles in the contesting rag.


Title: Re: vertical antennas
Post by: K5UJ on June 02, 2011, 02:06:07 PM

<<Hereís an interesting article on radials and getting the most out of a given amount of wire. It predates the QEX articles.>>

At the risk of being considered an irritant once again by not seeming to offer encouragment, I read that article not long after it came out and found its premise flawed.   The idea of having a finite amount of wire and planning an entire ground system with that as a limiting factor is completely wrong, unless all wire and cable manufacturing ceases and the cost of remaining supplies goes up by an order of magnitude or more.

It is much wiser to go ahead with the best most complete ground system possible within the limits of one's property lines, and upon running out of wire, halt the installation until more can be purchased and continue in increments until finished, rather than install a compromise ground system based on N feet of wire on hand, considering the entire project finished, once the current wire supply is exhausted.

Where this method might make sense is for a temporary ground system for a dxpedition antenna or Field Day.


 


Title: Re: vertical antennas
Post by: flintstone mop on June 02, 2011, 02:40:19 PM
Hereís an interesting article on radials and getting the most out of a given amount of wire. It predates the QEX articles.




I donít subscribe to QEX, so I missed the article you mentioned. However, Iím not surprised that fewer radials work better if theyíre shorter. The dielectric constant of the various types of soil and rock varies by nearly a factor of 10, but if you take an average value youíd expect a radial buried deep in soil to be about one-third the length that it is in free space for the same resonant frequency. The dielectric medium doesnít normally completely surround the radial for a significant distance in all directions, of course, because it usually isnít buried that deep, so it might need to be half the normal length for resonance in free space instead of one third.  



And read on that the article is talking about a 1/4 wave vertical. So us folks messing with miracle 27 foot high masts and top loading and capacity hats or even more magical 43 foot 'antennas' are not going to benefit from the findings.


Title: Re: vertical antennas
Post by: W3GMS on June 02, 2011, 04:53:50 PM

"This set-up has been run up to about 800 watts carrier at 130+% positive peak modulation"

Hi Don,
Now I know why your so strong up this way :)
Joe, W3GMS   


Title: Re: vertical antennas
Post by: G3UUR on June 02, 2011, 05:22:10 PM
Although I can see why the radials might need to be resonant if you use very few of them, I still believe that saturating the ground at the base of the vertical with copper wire is the best way to go, especially if the length of the radials is very limited. I favor putting down whatever I can fit in until I no longer measure any improvement in field strength at a distance.

Iím suspicious of these NEC4 simulations where the effect of ground is critical to the results and the authors have not done any controlled experiments to verify even a tiny part of their simulated data. Iíve heard that even NEC4D, the professional version, does not simulate ground effects very well. Because of this, and also because itís sensible, they ought to be using simulations in conjunction with experimental results to get a better understanding of how things work and gain more insight, not blindly using them without checking.

Don, I think the sharp tuning you observe on 160m with your current set-up is more to do with the tremendous working Q of the tuning unit than the low loss of your system as a whole. Youíre probably working with a Q of over 100 at the moment. The capacitor can take it because the voltage rating of variable capacitors in the old days was usually based on the DC supply voltage and not the RF, so your capacitors should be able to stand 14kV peak with some margin. 

 I should warn you that my suggestion for matching your 80m dipole on 160m with just the quarter-wavelength of open-wire feeder is based on free space values of radiation resistance and reactance for the dipole, so you might need to vary the shunt inductor and series capacitors a bit to get the best match to 50 ohms. Youíre right, each of the series capacitors can be considered to be a composite of two in series, one canceling the reactance looking into the feed line and the other providing the matching to 50 ohms with the shunt inductor. In this case the capacitor in each leg of the feeder is set at a lower capacitance than that required just for reactance cancellation.

There is another possibility, which you might like to consider, and that is to set the series capacitors at a slightly higher capacitance so that the inductive reactance is not fully canceled and there is some residual inductance that can be used with a shunt capacitor across the feeders at the 50-ohm input end. This will require a capacitor of around 3000pF plus or minus some, depending on the exact value of the radiation resistance of the 80m dipole on 160m. It might be worth comparing the two versions to see which one gives the broadest bandwidth.

Dave. 


Title: Re: vertical antennas
Post by: k4kyv on June 02, 2011, 06:10:54 PM
At the risk of being considered an irritant once again by not seeming to offer encouragement, I read that article not long after it came out and found its premise flawed.   The idea of having a finite amount of wire and planning an entire ground system with that as a limiting factor is completely wrong, unless all wire and cable manufacturing ceases and the cost of remaining supplies goes up by an order of magnitude or more.

That is true.  Starting out designing a limited radial system based only on a roll of wire on hand and letting that be it seems too Hammy Hambone-ish to me, but the articles are interesting regarding the most efficient use of a given amount of wire. Perhaps for the first round one could lay a limited number of short radials for the most efficient use of the short roll, and later on plan to inter-lay longer radials in between. Some broadcast installations double up the number near the base using shorter radial wires, with the normal count of 120 on out to a quarter wavelength. This has proved to be a more efficient use of copper than using a mesh screen near the base of the tower. Of course, we must remember that regardless of length, radials are not "resonant" when buried in the earth as they are when elevated above-ground.

I planned way ahead with mine, with the idea of some day having a place to lay a full commercial grade radial system. I found a source of affordable wire, bought a 16,000 ft. roll of #12 bare soft-drawn, and stored it away in the event I would ever be able to use it.  About 6 years later, moved back here and a couple of years later the wire was buried. It had been in storage for 8 years by the time I installed the radials.

In retrospect, I might have been better off just burying 60 quarter-wave radials, and saving the rest of the wire for additional radial systems, but at the time I never suspected that copper was going to turn into a semi-precious metal. From numerous charts I have seen, the critical point of diminishing returns occurs at about 60 quarter-wave radials, and the difference between 60 and 120 is a tiny fraction of a dB. Or I might have used more than 60 but fewer than 120, making them all longer than 1/4λ, although that might have taken up more field space than I would have wanted.



Dave,

I want to keep the system simple, so that only one capacitor, the split stator, is varied with frequency, now that I am using 5 separate capacitors in 5 separate tuners ganged together to the reversible motor in the antenna tuner. With the series arrangement, two capacitors would have to be ganged together with insulated shafts and frames. I don't think the idea of splitting the coil and feeding the resonant feeders at the gap would work, given the high amount of reactance that would be inserted into the inductor at the gap. Feeding at the gap would work with a lo-Z non-reactive load, and I could still use the split stator, but in this case the load is highly reactive. It would take a lot of mechanical re-building to use two isolated capacitors instead of the one big split stator.

But I still might throw together an experimental set-up just to see how it works. In any case, I plan to sooner or later replace the 50Ω transmission line with 440Ω OWL, with the tuner used to convert balanced flat OWL line from the shack to the resonant feeders that run from the tuner at the base, up the tower, to the dipole. The long total length of OWL would complicate using resonant feeders all the way from the dipole, down the tower,  to the transmitter in the shack, because the cumulative error when QSYing across certain bands, resulting from the large count of quarter-wavelengths in the resonant line, would make it difficult to maintain series or parallel tuning with one simple split stator variable capacitor all the way across each entire band. Plus, the 140 ft. run from the shack to the tower would have less loss if it ran as a flat line  than if it ran as tuned feeders.



Title: Re: vertical antennas
Post by: KM1H on June 02, 2011, 08:53:32 PM
Quote
Steve, that is a good article on ground radials.  Thanks for posting the link. I wasn't aware that there were technical articles in the contesting rag.

The NCJ is about the only place you will find quality articles published. Contesters take performance seriously.

As far as 43', W1FV has been using that length on 80/160 since the 80's in 4 squares and has published a few times in the NCJ and maybe QEX. John is a one of those MIT guys that knows his stuff.

Carl


Title: Re: vertical antennas
Post by: Steve - K4HX on June 02, 2011, 09:55:42 PM
Don:

With 119 feet of feedline on your 80 M dipole, the impedance at the end of the feedline on 160 meters is like 8 - j436. Adding another 60 feet yields 7 + j70. Seems the latter would be easier to tune.

An Inverted-L, 60 feet up and 60 feet out will have little high angle radiation. Over ground with average conductivity and with 30 quarter-wave radials, the peak is at 26 degrees. At 60 degrees elevation the L is down about 8 dB compared to a dipole at 60 feet. At 70 and 80 degrees respectively, the L is down about 10 and 12 dB compared to a dipole.

The original poster doesn't have space for a full-sized dipole, so the  L might be his only option. But for local work, even a short dipole would probably be better.


Title: Re: vertical antennas
Post by: k4kyv on June 02, 2011, 11:26:02 PM

The NCJ is about the only place you will find quality articles published. Contesters take performance seriously.


Looks like further fragmentation of technical information published by the League.  Once upon a time all the technical information was published in QST, the Handbook plus, for those interested, the speciality handbooks (antennas, SSB, Hints & Kinks, mobile etc). Now you have to subscribe to three periodicals in addition to purchasing the speciality publications to get all the technical articles... and the least fruitful of these is QST, the default membership publication.  However, lately I have seen some improvement in the technical content in QST.


Title: Re: vertical antennas
Post by: G3UUR on June 03, 2011, 04:17:57 AM
Steve, while I agree with you on two points, I strongly disagree with you on the third. Taking the one where we disagree first; a short dipole on 80m at 120ft will have a radiation resistance between 12 and 16 ohms and look capacitive on 160m. Roughly halfway down the 119ft OWL section it will look purely resistive at 6 to 8 ohms. If the OWL is 500 to 600 ohms the low resistance at the halfway point will be transformed to an inductive reactance in series with a low resistance at the bottom because itís a further one-eighth of a wavelength to that point.

I agree that the amount of power radiated from the top section of an inverted-L drops as the height of a quarter-wave inverted-L is increased, and pointed out to Don in a previous posting that he was not comparing like with like since Gary (AE1CT) would be using only about 30ft of vertical and a 100ft top.

I agree that Garyís best approach might be an inverted-L in the long run, but the folded horizontal doublet would be easier to implement in the first place given that he will have to put in a lot of work to lay down a satisfactory ground system for the inverted-L. Using a doublet for a season would also allow him to assess his noise situation with a balanced antenna.

Don, if you only need to shift about 5 kHz before you notice a significant increase in SWR, then your system -3dB bandwidth could be as low as 15 kHz. This corresponds to a system working Q of 127!!!  The Q of your antenna and feeder system alone ought to be 40 to 50, so you should to be able to gain an increase in bandwidth of well over 2 if you use the simplest matching arrangement possible. Thatís what Iím suggesting.

You only need two ganged, isolated variable capacitors and one small inductor (or possibly another large fixed capacitor) to implement the tuning system that Iím advocating. This is the simplest possible arrangement you can use to match your antenna system with an 80m dipole on 160m. There is no simpler way, unless you do the matching at the top of the tower, and it doesnít increase the overall working Q, because that is already defined by the reactance and radiation resistance and with my simple matching and tuning arrangement youíre making it no worse. The Q of the 50-ohm matching circuit is under 2 and hardly reduces the bandwidth at all.

You add to the overall Q of the system by using a matching unit that has a further tuned circuit, especially if it doesnít have a large enough inductance for the high impedance to be matched. Thatís what youíre currently doing. You may also be losing about 2dB in the tuner if the Q of your coil is 350 or so, but it could be worse if the Q is lower. Simple is best!

Carl, many 160m DXers in the UK used 40ft verticals, both top loaded and folded monopole, from small suburban plots to work all over the world using very low power in the Ď60s and Ď70s. There are probably some using the same arrangement these days but we're allowed higher power now. Iíve worked W1BB in mid summer with 2.5 watts input and a 40ft folded monopole on 160m, so you can have great fun and do quite well with a modest set-up, but you canít compete in a pile up with the Big Guns. Youíve got to know your propagation and be ahead of everyone else to snag the DX before the gang turn up. Thatís harder to do now because everyone is a propagation expert with all these computer aids.

Dave.


Title: Re: vertical antennas
Post by: KM1H on June 03, 2011, 08:15:30 AM
Dave, the 40-43' has been popular for a long time and was really popularized when the US was given the  full band and 1500W in the late 70's. Then 160 was included on DXpeditions an the 43' gained popularity. W1FV's contribution was to produce a high performing 4 Square with shortened radiators and only 1/8 wave spacing on 160 using the 80M array he had been already using.

Yes, 160 propagation is amazing at times, Ive worked 13 countries with 100mw on nights when every EU with 100W or less to a wet noodle was at least 20 over S9.

I was looking at a full 1/4 wave L for my 500 KHz antenna and didnt like the modeling results with only 170' being vertical. Efficiency and bandwidth were better with 4 140' sloping top hat wires than the roughly single 325' top wire.

Carl


Title: Re: vertical antennas
Post by: K5UJ on June 03, 2011, 09:24:51 AM
Some of the physically small antennas written about here and there may provide some satisfaction for contesting and dx chasing but one must keep in mind that these activities involve short QSOs, and narrow bandwidth efficient modes.   Firstly, if all one has space for, is a physically small antenna then he should go with that and hope for the best.  But for AM the deck is stacked against us (which makes for a challenge I enjoy) with its poorer S/N due to a wider passband on receive, and lower power density on transmit due to the spread of the same wide bandwidth and intelligence in the lower powered sidebands.  The beautiful sound of AM has a price in other words, making a good antenna all the more important if one is going to have a satisfying experience.  To get back to the original questioner I think this was one of the reasons why  K1JJ was emphasizing the importance of having a good antenna.   There is a tendency to give a newcomer a rosy picture but I will not lead anyone to believe low power and a small loaded antenna is anything other than a beginning.

To be sure, there is a lot to learn about antennas from the contesting and dxing community, expeciallly in the area of tower construction, feedlines, modeling, receive antennas, phasing and other topics so I am not discrediting them by any means.  Ultimately, AE1CT will have to experiment, which can be a lot of fun itself, and reach his own conclusions.



Title: Re: vertical antennas
Post by: Steve - K4HX on June 03, 2011, 09:57:19 AM
Completely untrue. In the past 73, CQ and Radio and other rags had technical articles - often superior to those of QST. The west coast handbook was better than the ARRL handbook too.




The NCJ is about the only place you will find quality articles published. Contesters take performance seriously.


Looks like further fragmentation of technical information published by the League.  Once upon a time all the technical information was published in QST, the Handbook plus, for those interested, the speciality handbooks (antennas, SSB, Hints & Kinks, mobile etc). Now you have to subscribe to three periodicals in addition to purchasing the speciality publications to get all the technical articles... and the least fruitful of these is QST, the default membership publication.  However, lately I have seen some improvement in the technical content in QST.


Title: Re: vertical antennas
Post by: Steve - K4HX on June 03, 2011, 10:04:00 AM
The 43 foot vertical is popular because it can be used on 40-10 meters when fed with coax and tuned with a tuner in the shack. If the coax is of reasonable length, the loss will be acceptable. Making it work on 160 and 80 is possible but not nearly as simple.


Dave, the 40-43' has been popular for a long time and was really popularized when the US was given the  full band and 1500W in the late 70's. Then 160 was included on DXpeditions an the 43' gained popularity. W1FV's contribution was to produce a high performing 4 Square with shortened radiators and only 1/8 wave spacing on 160 using the 80M array he had been already using.

Yes, 160 propagation is amazing at times, Ive worked 13 countries with 100mw on nights when every EU with 100W or less to a wet noodle was at least 20 over S9.

I was looking at a full 1/4 wave L for my 500 KHz antenna and didnt like the modeling results with only 170' being vertical. Efficiency and bandwidth were better with 4 140' sloping top hat wires than the roughly single 325' top wire.

Carl


Title: Re: vertical antennas
Post by: Steve - K4HX on June 03, 2011, 10:56:16 AM
I modeled Donís dipole over real ground. The feedpoint impedance was something like 18 Ė j1000. I think I forgot the Ė sign when entering the Z into TL. Now I get 9 + j290 at the end of 119 feet of 600 Ohm OWL. Adding 60 feet yields 62 Ė j1500. That will teach me to do this stuff late at night!

Quote
Taking the one where we disagree first; a short dipole on 80m at 120ft will have a radiation resistance between 12 and 16 ohms and look capacitive on 160m. Roughly halfway down the 119ft OWL section it will look purely resistive at 6 to 8 ohms. If the OWL is 500 to 600 ohms the low resistance at the halfway point will be transformed to an inductive reactance in series with a low resistance at the bottom because itís a further one-eighth of a wavelength to that point.


Title: Re: vertical antennas
Post by: G3UUR on June 03, 2011, 12:54:48 PM
Steve, glad you got the modeling sorted out. Thatíll teach you to be too reliant on computers! From your figures it looks as if Don will need larger series capacitors than I suggested, and a smaller shunt inductor.

Carl, when I first got on 160m in 1963, the 41ft vertical was already very popular with British 160m DXers because they could use it all the way up to 20m with a modest ground system from quite back small gardens. They even got some gain on 20m because the antenna was 5/8 wavelength on that band, Most switched matching circuits manually at the base to change bands because they didnít have to walk far to do this. They had no interest in working other UK stations on AM apart from comparing notes on 160m with their local rivals, and the vertical was ideal for that, of course, because of its strong local ground wave. Obviously, this doesnít fit the bill for Gary (AE1CT) because heís interested in working around New England on 75m AM, as well as operating 160m, and the skip zone with a vertical is not going to be conducive to that. I think it was Fred who said that those using this ďmagic 43ft antennaĒ have to use a top loading wire to get it to work reasonably well. Do they add enough to produce a reasonable amount of NVIS, or is it just to make the vertical more efficient for ground wave and low-angle, sky-wave work?

Iím very sceptical about this 4-square arrangement, Carl, because with only 43ft verticals and 1/8 wavelength spacing on 160m the array gain would probably be offset by the increased loss in each vertical compared to one vertical with no interaction. It will obviously help on receive because of the directivity, but there are easier ways of getting directivity for receive only. If you get very little increase in transmit gain, it seems hardly worth going to all the effort of a 4-square array unless you already use it on 80m. Anyway, it has no bearing on Garyís predicament, so we ought not to be discussing it on this thread, interesting though it may be.

K5UJ is right to be concerned that Garyís desire to operate AM from a small plot is going make things harder for him. I agree, but itís not going to make things impossible, and heíll get a tremendous amount of enjoyment out of being able to put out a half-decent signal over 200 to 300 miles with modest power. If I had to describe a typical British 80m AM station these days, he would probably be using a G5RV with the centre at about 25ft and a DC input of 50W. These guys have no trouble working each other during the early mornings and late afternoons, and signal strengths improve enormously as darkness approaches and the D-layer attenuation fades away. Conditions do become a problem for them at noon during periods of high sunspot activity when D-layer attenuation is high, or the E-layer ionization is so strong and flat that nothing much gets reflected back, but otherwise they have great fun and get plenty of enjoyment from their hobby. Some of them get on 160m in the winter by adding end loading to their G5RVs. If youíre still monitoring this thread, Gary, I hope what Iíve described here gives you some encouragement.

Dave.


Title: Re: vertical antennas
Post by: W2DU on June 03, 2011, 01:57:31 PM
Did I just hear someone mention 'a reasonable amount of NVIS from a vertical'? I'm aghast!

Walt


Title: Re: vertical antennas
Post by: k4kyv on June 03, 2011, 02:07:44 PM

Don, if you only need to shift about 5 kHz before you notice a significant increase in SWR, then your system -3dB bandwidth could be as low as 15 kHz. This corresponds to a system working Q of 127!!!  The Q of your antenna and feeder system alone ought to be 40 to 50, so you should to be able to gain an increase in bandwidth of well over 2 if you use the simplest matching arrangement possible. Thatís what Iím suggesting.

My mental picture of your suggestion would be a balanced tuner, with a coil and two variable capacitors. Each variable would be in series with one of the legs of the tuned OWL that feeds the dipole, with the other side of each cap connected to one end of the coil. The transmission line from the shack could be coupled to the tuner either by (1) a separate link tightly coupled and physically located at the mid-point of the coil, with the number of turns adjusted for the best match at resonance to make the transmission line from the shack as flat SWR-wise as possible, or else (2) by tapping the transmission line from the shack directly to two points symmetrically located about the mid-point of the coil (same basic configuration as separate link coil, except the main coil would be used as an autotransformer). The spacing between taps would be adjusted for the best match. Do I get the picture correctly?

Another possibility with the above configuration would be to split the coil and insert the untuned transmission line from the shack to the gap, and adjust the capacitors and number of turns in each half of the coil for the best match, making it sort of a balanced L-network.

Any one of those basic configurations ought to work equally well with 50Ω coax or with balanced (440Ω) OWL serving as a flat untuned line running back to the shack, with appropriate adjustments to capacitances and inductances.

Attached is a photo of the present 160m dipole tuner. The link-coupled coil is seen mounted vertically in the corner, and next to it is the split stator capacitor, with the worm-drive and reversible motor mounted on the top end. The shafts at either end of the variable cap are coupled to 90į drive mechanisms, each of which is coupled to two more variable capacitors mounted horizontally along the top and bottom of the box and used to resonate additional tuners.


Title: Re: vertical antennas
Post by: G3UUR on June 03, 2011, 02:09:26 PM
No, but you might just have read something about it, Walt.

And, be clear, the reference is to a single horizontal top-loading wire added to a vertical, in which case it becomes an inverted-L with 43ft of vertical and whatever length of horizontal wire. Some NVIS will come off this wire and the amount will increase as the wire is lengthened. I was enquiring about whether they did it to produce some NVIS or just to pull the current more up into the vertical section to increase the efficiency.

Dave.


Title: Re: vertical antennas
Post by: G3UUR on June 03, 2011, 02:23:37 PM
Hi Don,

You just caught me on the hop typing a reply to a mischievous comment by Walt.

No, the 50-ohm coax can be connected straight across the small inductor since you can alter its inductance and tweak the capacitors to get a perfect match at this point. If you run your 50-ohm coax underground to the bottom of the tower you might get away without using a balun, otherwise,heaven forbid, you might have to use a W2DU choke balun! If you've got a hefty ferrite core lying around you could go for a W1JR choke balun instead.

That tuner look impressive. It'll be a shame if you can't find another use for it, but the existing application doesn't really require it and actually makes the situation worse.

Steve's simulation on a computer suggests that you might need larger series capacitors than my back-of-a-cigarette-packet calculations suggest, so be prepared for adding a bit more capacitance across your series capacitors in the prototype if necessary. His figures also suggest reducing the shunt inductance a tad as well, but that's pretty small anyway.

Dave. 


Title: Re: vertical antennas
Post by: k4kyv on June 03, 2011, 02:37:51 PM
Here is another shot showing the rest of the tuners and how everything is ganged together. I forgot to attach it to the previous message.

Walt and Dave, couldn't one at least approximately achieve NVIS radiation using a long vertical, several wavelengths tall? There would still be a sharp null straight up, but there would also be near-vertical high angle radiation that could illuminate very closely to the antenna.

Since my results using the 160m vertical as a half wave on 80m have been disappointing, consistently getting poorer signal reports at all distances including west coast USA and Europe than with the dipole (also a half-wavelength high), I have considered re-tuning the 80m 1/2λ vertical to make it a full-wave vertical on 40m. According to the theoretical charts, the main omni-directional lobes would be at about 50į take-off angle, which should work well for stations at distances a few hundred miles away in N America, useful during daylight hours, and maybe fill in some areas where the 80m dipole operating as a double-Zepp has nulls.  It's at least worth a try, since I have all the needed stuff on hand.


Title: Re: vertical antennas
Post by: G3UUR on June 03, 2011, 03:44:05 PM
Don,

That's very odd about the half-wave vertical on 80m. You'd expect it to go great guns on 80m. I wonder what the ground conductivity is like around your property. You mentioned in a previous posting that you got better results 50 miles away on sky wave than you did on ground wave, which considering your power points to quite poor soil conductivity in one direction at least. I wonder if the problem is related to too high a Brewster angle for vertically polarized signals in your locality.

You're right, NVIS could be achieved with a long (high) vertical. In fact, if you made one just a wavelength long you could cancel the low angle pretty well.

Dave.     


Title: Re: vertical antennas
Post by: k4kyv on June 03, 2011, 04:07:18 PM
Dave, the 40-43' has been popular for a long time and was really popularized when the US was given the  full band and 1500W in the late 70's.

Carl, you need to read up on your history.  The US was NOT "given the full band and 1500W in the late 70's".

There was nothing in the regs that even mentioned 1500W back then; the legal limit was 1 KW DC input to the final, and the full 1800-2000 kc/s wasn't given back until sometime in the mid-1980s. 

In 1979, the 1800-2000 kc/s portion was returned to us in the ITU regulations at the WARC conference, but the FCC sat on its hands and did nothing until sometime about 1981 IIRC, after ARRL and others had petitioned to restore that full portion of the band. But we got only 1800-1900 back, because in some obscure localitiy, reportedly in Canada, LORAN had not yet been completely phased out. Eventually we got the full 1800-2000, but almost immediately 1900-2000 was reallocated to Radiolocation on a primary basis, and amateurs were relegated to the status of secondary users. This was allegedly for the purpose of "reaccommodating" the radiolocation beacons as they were displaced by the expansion of the AM broadcast band.  Within weeks, radiolocation beacons began to appear in the band, but it would be years before the first AMBC station (the one in Elizabeth, NJ) appeared in the extended portion. The only thing that saved the amateur band above 1900 was the advent of GPS. As units became more widely available at low cost, and civilian users were given full resolution down to a few feet, the beacons one by one disappeared from the amateur band, although technically we are still secondary users of 1900-2000.

But even with 1800-2000 kc/s the full band has never been restored to amateurs.  Before WWII, for many years the band was 1715-2000, and for a brief period just before Pearl Harbor the allocation was shifted to 1750-2050, but I am not sure if US amateurs ever actually got to use that full 300 kc/s of band before the shut-down.


Title: Re: vertical antennas
Post by: Steve - K4HX on June 03, 2011, 04:07:37 PM
Iíve seen some YouTube vids of some of these guys. The signals were quite good. I can often copy some UK stations on 3615 or 3625 kHz at around 0600Z or so, especially in the winter months.

On the dreaded slopbucket, Iíve worked a ton of 10 and 50W stations out of the UK. Many are using verticals with modest radial systems or doublets at a height of 30 feet or so. Tom/JJ often calls CQ just for those guys. Itís a hoot hearing a pile-up of 10 Watt signals!

Yes, a small lot and low power is a challenge. But more can be done than first thought, if you are willing to work at it.


Quote
If I had to describe a typical British 80m AM station these days, he would probably be using a G5RV with the centre at about 25ft and a DC input of 50W.


Title: Re: vertical antennas
Post by: WD8BIL on June 03, 2011, 04:21:26 PM
Quote
You're right, NVIS could be achieved with a long (high) vertical. In fact, if you made one just a wavelength long you could cancel the low angle pretty well.

I'm not sure what you mean here, Dave. It looks like a full wave vertical is all low angle.?


Title: Re: vertical antennas
Post by: k4kyv on June 03, 2011, 04:44:02 PM
I have seen a few of those "back gardens" in cities in the UK, so the real estate for a 160m vertical would be pretty limited. But some UK hams do live in the country where there is more room. Rob, K5UJ describes his place in the Chicago area as pretty much the same, yet I have heard him put out quite a dominating signal on 160m as well as 75. The best strategy would be to lay as many short radials as you can afford the wire for, and make them as long as space permits, and use some kind of top loading on the vertical. A little fire in the wire wouldn't hurt, either (antennas by Eimac  ;)).

According to a source to remain unnamed, some of the "10-watt" top band stations in the UK are actually using retired tube type AM broadcast transmitters running as much as a KW carrier output. If true, I'm not sure where the transmitters came from, because I don't think there ever were a lot of independent 1KW size AM broadcasters in UK or elsewhere in western Europe for that matter, and the cost would be prohibitive to have one shipped from the US or from Canada.

Bud, as I recall, the chart that I saw showed the full wave vertical with the main lobe at a somewhat higher angle, with another very low angle secondary lobe that was a lot weaker. I have it here somewhere in one of my radio books. That low angle lobe might be enough to allow the antenna to work for DX.


Title: Re: vertical antennas
Post by: KM1H on June 03, 2011, 05:29:40 PM
Quote
Completely untrue. In the past 73, CQ and Radio and other rags had technical articles - often superior to those of QST. The west coast handbook was better than the ARRL handbook too.

Completely true, we are discussing current publishing, not ancient history and besides you forgot HRM.


Title: Re: vertical antennas
Post by: KM1H on June 03, 2011, 05:52:19 PM
Quote
Iím very sceptical about this 4-square arrangement, Carl, because with only 43ft verticals and 1/8 wavelength spacing on 160m the array gain would probably be offset by the increased loss in each vertical compared to one vertical with no interaction. It will obviously help on receive because of the directivity, but there are easier ways of getting directivity for receive only. If you get very little increase in transmit gain, it seems hardly worth going to all the effort of a 4-square array unless you already use it on 80m. Anyway, it has no bearing on Garyís predicament, so we ought not to be discussing it on this thread, interesting though it may be.

Skeptical you may be but John has made it perform very well as a dual band array. The 1/8 wave spacing offers about the highest gain but mutuals are very hard to control with a full 1/4 wave element. With the losses of the short element it becomes possible and with noticable gain.

Quote
Carl, you need to read up on your history.  The US was NOT "given the full band and 1500W in the late 70's".

Don Im not going to quibble over a few years; WARC, 160 band privileges and 1500W all happened very close together. I dont keep stcky notes on my monitor for trivia ;D

The fishing beacons are still operating down in the low end, I hear them often around 1820-1830 peaking SE from here.

Carl




Title: Re: vertical antennas
Post by: K5UJ on June 03, 2011, 10:57:46 PM
<<Rob, K5UJ describes his place in the Chicago area as pretty much the same, yet I have heard him put out quite a dominating signal on 160m as well as 75.>>

Tnx Don; coming from you I feel like the 101 radials (because I had to have over 100) were not a waste of time and copper!

Rob


Title: Re: vertical antennas
Post by: k4kyv on June 03, 2011, 11:08:18 PM

Don Im not going to quibble over a few years; WARC, 160 band privileges and 1500W all happened very close together. I dont keep stcky notes on my monitor for trivia ;D

The fishing beacons are still operating down in the low end, I hear them often around 1820-1830 peaking SE from here.

One of the things that kind of irks me is the number of newbies who think the 1500w bullsh!t has always been the standard.  And most of the fishing beacons down at the low end (illegal, since the shared portion of the band is 1900-2000 and doesn't include 1820-30) are so PW that they don't bother me. Like the bootleg CBers on 10m, I suggest we just turn up the wick and blast them to oblivion.


Title: Re: vertical antennas
Post by: G3UUR on June 04, 2011, 07:24:44 AM
Bud, youíve got to remember that Iím not good enough to be an engineer, and thatís why I became a scientist! My response about the one-wavelength vertical was an idle answer to a casual question and I was just thinking of canceling radiation at zero degrees and the two opposing half-wave current sections in a full-wave end-fed vertical will do that. If you want to nit pick, my comment about NVIS is not that accurate, either, because no vertical, no matter how long, will produce anything going straight up. Nor is a 32 degree main lobe that low an angle of launch, either. How low is low? I donít think we want to get into debating that!

Carl, Iím not convinced by claims that something works ďvery wellĒ and would have to ask how bad it has to work before itís considered to just work well? There is also no way of knowing how much Johnís location influences his results, either.

Don, the power limit in the UK is now 400 watts output from 1810 to 1850 kHz, and above 1850 kHz itís 15dBW (32 watts PEP). In the old days there were always DX fanatics who ran illegal power, but many of us stuck to 10 watts, or under, just for the challenge of it. We knew who the cheats were, and I could give you their call signs, but wonít for fear of legal action!  Even with the increased power limit these days, there are those who run 1500 watts output on SSB and CW at the low end of 160m because thatís what they can get out of their commercial amplifiers. Iíve even heard them up on the high end running high power sometimes Ė they donít appear to know that there is a lower limit up there and what theyíre doing is that much more obvious! I imagine they donít care. Whoís going to take them to task? OFCOM (our FCC) certainly arenít going to do it.  They donít have the manpower to do anything anymore.

There are still many 160m AM stations running 10 watts, or less, DC input in the UK and they quite happily chat locally with very modest antenna systems. Those who put a bit more effort into improving their antennas do better and work further a field. The most common PA tube in use on 160m AM is the 6BW6 (electrical equivalent of the 6CM6) and you would be hard pressed to run more than 12 watts input to one of them. If you did, the modulator would not provide enough audio to modulate it fully anyway. Thereís still a lot of fun to be had with low power AM on 160m, though in the States it would be more difficult because of interference from high-power stations.
The high-power boys very rarely come above 1850 kHz, so we donít have too much trouble form them. Iím sure plenty of the SSB stations above 1850 kHz are running 100 watts out rather than 32 watts PEP, but we donít generally get a lot of trouble from them. Our main source of interference is USB from Irish, Dutch and Danish trawler men.

Dave.


Title: Re: vertical antennas
Post by: K5UJ on June 04, 2011, 02:23:17 PM
Dave,  what is the ground conductivity like in the UK?  It is okay at my location, not great but not bad either, but in some parts of the US it is nonexistent.

Rob


Title: Re: vertical antennas
Post by: G3UUR on June 04, 2011, 03:17:58 PM
Rob,

Generally, the soil conductivity is not bad in England. There are large parts of the country where the soil conductivity is 10 to 15, or even 10 to 20 mS, such as the Midlands, around Cambridgeshire and Lincolnshire. Other parts are between 4 and 10 mS, whereas Cornwall and Devon are down below 3 mS. Large parts of Northern Scotland are also below 3 mS. In Wales there is a reasonable coastal strip in the south where it's 5 to 10 mS. but for the rest of Wales, it's poor at either below 5, or in some parts below 3 mS.

Where I live in the bulge on the eastern side of the country, it's 5 to 10 mS, so not too bad and not too good, either.

There is a map of the conductivity around the country, produced by the BBC, but I'm not sure if anyone has reproduced it on the web. If we wait long enough, Steve may come up and tell us where to find it.

Dave.


Title: Re: vertical antennas
Post by: G3UUR on June 04, 2011, 03:48:30 PM
Rob,

I've just found a ground conductivity map for the whole world, which appears to be from a CCIR document. You can download it from HAMWAVES at

http://hamwaves.com/antennas/gnd-sigma/vlf_mf_ground_conductivity_atlas.pdf

Dave.


Title: Re: vertical antennas
Post by: k4kyv on June 04, 2011, 03:53:41 PM
Don,

That's very odd about the half-wave vertical on 80m. You'd expect it to go great guns on 80m. I wonder what the ground conductivity is like around your property. You mentioned in a previous posting that you got better results 50 miles away on sky wave than you did on ground wave, which considering your power points to quite poor soil conductivity in one direction at least.

Dave.     

Looks like we're at least 4 but less than 8 millimhos per metre. I am close to a border area, and I doubt that it suddenly jumps from 4 to 8 precisely on the line shown on the map. The figures must be average values calculated over the entireties of the areas shown.

http://filebay1.home.comcast.net/~filebay1/ground.jpg


Title: Re: vertical antennas
Post by: G3UUR on June 04, 2011, 04:04:51 PM
Hello Don.

I was just looking at the ground conductivity map of the US on the FCC site and wondering if you were in the 2mS/m part of TN. I don't exactly know which part of the State you're in, but it's obviously not that part in the east where it's really bad.

I don't know how they gather the data for these maps, or whether they average the figures out over the year, or not. The figures must depend on the moisture content of the soil, so it would be interesting to know how they deal with that. Perhaps the CCIR document mentions it somewhere. I'll have to read it in full.

Dave.


Title: Re: vertical antennas
Post by: KM1H on June 04, 2011, 07:03:14 PM
There seems to be quite a difference for some places between those 2 maps but Im my expected 1 on both.


Title: Re: vertical antennas
Post by: k4kyv on June 04, 2011, 07:53:23 PM
Hello Don.

I was just looking at the ground conductivity map of the US on the FCC site and wondering if you were in the 2mS/m part of TN. I don't exactly know which part of the State you're in, but it's obviously not that part in the east where it's really bad.

Scroll down to the 100 mi/200 km scale.


http://maps.google.com/maps?q=woodlawn+tn&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&um=1&ie=UTF-8&hq=&hnear=0x8864d51e75b573ef:0x6b9d02d9f7fca55,Woodlawn,+TN&gl=us&ei=m8TqTZKECY72gAfWhYTYCQ&sa=X&oi=geocode_result&ct=image&resnum=1&ved=0CCEQ8gEwAA


Title: Re: vertical antennas
Post by: WD8BIL on June 04, 2011, 08:49:29 PM
Not nit-pickin', Dave. It's been a while since I've delved into this and was assuming you knew something I hadn't heard before/yet. No offence intended. I was just interested in what it was you meant. Please don't read a slap where none was meant.



Title: Re: vertical antennas
Post by: K5UJ on June 04, 2011, 10:43:54 PM
Dave, thanks for the g.c. information for the UK.  The FCC map of the US that is frequently published accompanying this topic in books is pretty old.  I have no idea how they obtained the data and how accurate it is.  As far as I know, it is all we have here, that is, until now.  I'll have to study that "atlas" source you put a link up for.   I think I am in a slightly above average location (probably wishful thinking) because I am in a low lying area near a river bank and the earth is moist most of the year.

Rob


Title: Re: vertical antennas
Post by: Sam KS2AM on June 04, 2011, 11:14:55 PM
Hello Don.

I was just looking at the ground conductivity map of the US on the FCC site and wondering if you were in the 2mS/m part of TN. I don't exactly know which part of the State you're in, but it's obviously not that part in the east where it's really bad.

Scroll down to the 100 mi/200 km scale.


http://maps.google.com/maps?q=woodlawn+tn&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&um=1&ie=UTF-8&hq=&hnear=0x8864d51e75b573ef:0x6b9d02d9f7fca55,Woodlawn,+TN&gl=us&ei=m8TqTZKECY72gAfWhYTYCQ&sa=X&oi=geocode_result&ct=image&resnum=1&ved=0CCEQ8gEwAA

and why are there five Woodlawns in Tennessee Don ?  ... lack of creativity   :P ?



Title: Re: vertical antennas
Post by: G3UUR on June 05, 2011, 04:18:49 AM
Iíve just found a very small version of the BBC ground conductivity map for the UK in an old 1966 copy of the RSGB Bulletin, and it doesnít agree too well with the CCIR map for the UK. Granted, the CCIR would have had difficulty getting the regional detail on a map of that scale, but even so the shape of the high-conductivity region around Lincolnshire and Cambridgeshire is wrong and specified as much more conductive than on the BBC version.

Bud, donít worry about offending me. If Iíve been sloppy and imprecise, I need to be pulled up about it. I ought to be more careful, especially on this forum with Steve always lurking. Oh, and never assume I know what I'm talking about. Like everyone else I sometimes get a bee in my bonnet about something, or other, but I'm wrong. There's an awful lot to learn in the world and I realize how little I know in total. It's humbling!

Don, thanks for the link to the map of your location. The relief, such as it is, makes it appear that youíre on the edge of the basin where the Cumberland River deposited some half-reasonable soil way back in time, and thereís low-conductivity rock between you and Nashville.

Youíre also rather close to Paducah. That could be real bad news in the future!

Sam, ďWoodlawnĒ seems to be a really popular name in the States. A couple of years ago, I traced a Peace Corps teacher I used to know when I was teaching on VSO (British Peace Corps) in Grenada way back, and he was teaching at a school of that name in Arlington, Virginia. ďSpringfieldĒ and various other names seems to be repeated quite a lot throughout the States as well. I suppose the pioneers liked to remind themselves of where they originated. When I try to keep up with the news on the Caribbean island of Grenada, I often get the news for some place in Mississippi or Louisiana coming up instead. Lack of imagination, possibly; but could just be the adult version of a comforter - human natureís a funny thing!

Dave.


Title: Re: vertical antennas
Post by: KA3VID on June 05, 2011, 09:57:21 AM
I suppose the bottom line to all this is a quote from the Slab Bacon himself and I quote"Get as much wire in the air as high as you can, feed it with  open wire ladder line and a robusto tuna then go to town wid it!" Werks fer me whenever I upgrade to General.


Title: Re: vertical antennas
Post by: G3UUR on June 05, 2011, 02:08:17 PM
That has been said many times, and goes back well before Slab said it. I don't think it's entirely true, though, since if you can get it high enough you can usually get away with less wire.

Dave.


Title: Re: vertical antennas
Post by: KA3VID on June 05, 2011, 03:59:46 PM
For all practical purposes this seems to be the best remedy.I have a
smaller back yard (garden) like the above person in the almost same predicament.A flat top with about 200 ft of wire fed with ladder line
at around 40 feet will be the best I will be able to do.Forget verticals with  radials My xyl would murder me if I even suggested such a monstrosity :)


Title: Re: vertical antennas
Post by: K5UJ on June 05, 2011, 04:31:47 PM
Forget verticals with  radials My xyl would murder me if I even suggested such a monstrosity :)

Well, I have to admit that any time someone asks me how to get all my antennas on a 50 x 100 foot lot, I always tell them the first thing you have to do is make your marital status single.


Title: Re: vertical antennas
Post by: KA3VID on June 05, 2011, 06:22:05 PM
Yep the story of my life in a nutshell LOL :)


Title: Re: vertical antennas
Post by: G3UUR on June 06, 2011, 10:17:16 AM
A flat top of 170 to 200 ft at a height of 40 ft is a good all-band antenna in my experience. I've used that arrangement at several of my previous locations with good success around the UK and Europe on 160, 80 and 40m. I did try a 240 ft top once and that was so much worse on 80m that I had to give up using it. Could never understand why, but others I've talked to who use similar antennas have found the same thing.

Dave.



Title: Re: vertical antennas
Post by: Steve - K4HX on June 06, 2011, 10:44:50 AM
I've never been to a town named Woodlawn but I've seen quite a few cemeteries with that name.

A 3/4 wavelength vertical will have a TO angle of something like 50 degrees. No, it's not NVIS, but not a bad angle for lots of non-DX type contact.


Title: Re: vertical antennas
Post by: G3UUR on June 06, 2011, 12:13:54 PM
Isn't there a minor lobe at a lower take-off angle as well, Steve?


Title: Re: vertical antennas
Post by: k4kyv on June 06, 2011, 12:42:42 PM
Forget verticals with radials My xyl would murder me if I even suggested such a monstrosity

What's the problem? A vertical, particularly a single mast (especially if you can get it to stay up unguyed) is probably the least imposing antenna structure you can erect, except maybe for a wire antenna with "natural" supports (trees). You don't have to tear up the lawn to bury the radials. Just clip them to the surface of the ground with stiff pieces of wire with hooks on one end, driven into the soil. This keeps the lawn mower from lifting the wire and getting tangled up with it. After a few weeks the wires will become invisible. Left undisturbed for a season or two, they will bury themselves, as thatch and sod form over the wire.

Regarding visible antennas on the property, whenever my wife grumbles about a radio project, I remind her that she knew about the radio long before she agreed to the marriage contract, and it was all part of a package deal.

I looked over those articles on radials in QEX, NCJ and the issue of QST in the footnotes, and interestingly, a full size quarter-wave vertical with just 4 to 8 short radials appears to be only 3-4 dB down from the same vertical with an optimum ground plane. The poor radial system can be compensated for by simply increasing power: "Ground Plane by Eimac". Of course, this doesn't work worth a hoot for a significantly shortened vertical; those little 16-ft commercially manufactured "No Radials Needed" verticals might perform reasonably well (with a big leen-yar) on 20 through 10m, but pretty well become dummy loads on 40 through 160.

I think the full wave vertical is supposed to have a very low angle minor lobe that might make it work for DX, but it is quite a few dB down from the main lobe, which is somewhere about 53į as I recall.  Minor lobes begin to become significant at about 5/8λ, which is why the 5/8WL broadcast verticals didn't prove satisfactory. They put out the maximum ground wave, but the high angle skywave radiation causes severe selective fading when it interferes with the ground wave.  This is known as the "fading wall". WSM had to chop about 80' off the tubular mast on top of the big Blaw-Knox tower to reduce a severe fading problem in Chattanooga.

"Woodlawn" is a very common name for graveyards all over the country. Here, it just happens to be the name (origin unknown) of the rural post office that delivers the mail; no official township with surveyed boundaries. There used to be little post offices scattered all over the countryside just a few miles apart, dating back to the days of horse-drawn vehicles, usually located in the rear of a grocery store or other business. About the time of WWII, they "consolidated" the little P.O.s into a few larger ones. Ours happened to be one of those that were saved to serve as a consolidated distribution point. When the grocery store was about to close (could no  longer compete with the big supermarkets in town), the P.O. purchased a plot of land next to the old one and erected a dedicated post office building, one of those little brick buildings with a flag out front that looks identical to millions of other small post offices all over the country. We don't have townships here; outside incorporated towns the only name for a community to go by is the name of the post office that serves it.  Many adjoining  communities still informally go by the name of the post office that used to be there but closed decades ago.  Some are downright funny, like Lickskillet, Possumtrot, Turtletown and Bucksnort. And of course, don't forget about the famous motel by the same name in Intercourse, PA.


Title: Re: vertical antennas
Post by: KM1H on June 06, 2011, 01:06:24 PM
If youre stuck on a small back yard then make all of it a ground plane by using the 2x2 or 2x4" welded, then galvanized and then green plastic dipped yard mesh sold at garden centers and box stores. See Freds version in another thread. Tack it down and maybe spread a inch of loam over it and the grass and its invisible and will function well for decades. As mentioned on here a few times it really improved my DX chasing at a prior QTH.

I know a guy who even buried it under his foundation and driveway during construction. A 100 x 100 lot is almost all a ground system and he gets out like gangbusters on 160/80 with a 43' stick. A couple of Slinky's along the lot lines give decent reception.

Carl


Title: Re: vertical antennas
Post by: w3jn on June 07, 2011, 06:10:59 PM
For all practical purposes this seems to be the best remedy.I have a
smaller back yard (garden) like the above person in the almost same predicament.A flat top with about 200 ft of wire fed with ladder line
at around 40 feet will be the best I will be able to do.Forget verticals with  radials My xyl would murder me if I even suggested such a monstrosity :)

That's about what I use at my Mt Airy, MD QTH.  But I made it a fan dipole, with the ends spread a few feet and one pair of conductors a foot or so shorter than the others.  Works FB, and even puts an acceptable signal on 160 with the GPT-750 and K1JJ tuna.  There's a, ahem, fair amount of circulating current in that tuna on 160 though.  The vacuum variable has a bit of talkback  ;D


Title: Re: vertical antennas
Post by: W2VW on June 07, 2011, 07:55:05 PM
I've never been to a town named Woodlawn but I've seen quite a few cemeteries with that name.


Did you start any arguments with the inhabitants? Just asking.


Title: Re: vertical antennas
Post by: KM1H on June 08, 2011, 12:07:55 PM
I wonder if ground conductivity is better in a cemetery or is it a RF dead spot?  ::) ;D

Carl


Title: Re: vertical antennas
Post by: WD8BIL on June 08, 2011, 01:26:58 PM
I guess, Carl, that might be determined by the ratio of wood to metal caskets?


Title: Re: vertical antennas
Post by: Steve - K4HX on June 08, 2011, 08:39:04 PM
I was invited to a few garden parties.



I've never been to a town named Woodlawn but I've seen quite a few cemeteries with that name.


Did you start any arguments with the inhabitants? Just asking.


Title: Re: vertical antennas
Post by: W2VW on June 08, 2011, 09:34:12 PM
I was invited to a few garden parties.



I've never been to a town named Woodlawn but I've seen quite a few cemeteries with that name.

Did you start any arguments with the inhabitants? Just asking.

Just remember you can't please everyone.....


Title: Re: vertical antennas
Post by: k4kyv on June 08, 2011, 11:42:52 PM
I guess, Carl, that might be determined by the ratio of wood to metal caskets?

http://www.therealmofterror.com/gallery/main.php?g2_itemId=1888

(http://2.bp.blogspot.com/_WPjZST8SC40/S9dE4I2YKTI/AAAAAAAA424/3LMQm4Kcxrs/s1600/cw.JPG)


Title: Re: vertical antennas
Post by: Steve - K4HX on June 09, 2011, 08:01:20 AM
But it's all right now.

I was invited to a few garden parties.



I've never been to a town named Woodlawn but I've seen quite a few cemeteries with that name.


Did you start any arguments with the inhabitants? Just asking.

Just remember you can't please everyone.....


Title: Re: vertical antennas
Post by: WD8BIL on June 09, 2011, 08:47:26 AM
Did you learn your lesson well, Steve?

Quote
But it's all right now.


Title: Re: vertical antennas
Post by: K1JJ on June 09, 2011, 09:43:42 AM
Did you learn your lesson well, Steve?

Quote
But it's all right now.


Did you sing them all the old songs, Steve?

Did they even know your name?

Since you got your new call, you don't look the same.


T


Title: Re: vertical antennas
Post by: The Slab Bacon on June 09, 2011, 09:56:44 AM
But, if you cant please everyone, you got to please your self................


Title: Re: vertical antennas
Post by: WD8BIL on June 09, 2011, 10:06:33 AM
But it's..... all right now
I learned my lesson well
Ya see ya can't freebase cocaine
a mile in the air! ;D


Title: Re: vertical antennas
Post by: Steve - K4HX on June 09, 2011, 01:24:18 PM
Oz never did give nothin' to the tin man.


Did you learn your lesson well, Steve?

Quote
But it's all right now.


Did you sing them all the old songs, Steve?

Did they even know your name?

Since you got your new call, you don't look the same.


T


Title: Re: vertical antennas
Post by: K1JJ on June 09, 2011, 01:44:17 PM
Sounds like you've lost that loving feeling.


The greatest rock star of the last 60 years?

http://www.youtube.com/watch?v=IfLvz0TIpOI&feature=related



Title: Re: vertical antennas
Post by: The Slab Bacon on June 09, 2011, 02:33:47 PM
Naaaaa, this is the man! ! ! !

http://www.youtube.com/watch?v=em-mjpaL2hs&feature=related


Title: Re: vertical antennas
Post by: WD8BIL on June 09, 2011, 02:44:11 PM
http://dalesdesigns.net/rock-on.htm


Title: Re: vertical antennas
Post by: The Slab Bacon on June 09, 2011, 02:58:30 PM
If Derb was still around, I think he'd vote for these  ;D  ;D


http://www.youtube.com/watch?v=ckV5NeB0tJY&feature=fvsr

http://www.youtube.com/watch?v=387ZDGSKVSg&feature=fvsr


Title: Re: vertical antennas
Post by: KB2WIG on June 09, 2011, 10:33:00 PM
You guys arre all pikers.


http://www.youtube.com/watch?v=XC73PHdQX04
                                                     ^
                                                     ^
                                                     ^
                         
klc
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands