10 Meter Antennas

[WA1GFZ]

I've never had any luck with a 75 meter loop close to the ground, simulation agrees. I bet an inverted Vee works better.

[w5omr]

The title of the article is: "Nested Full Wave Delta Loops for 20 and 10 Meters". Nothing to do with 75 meters. Further, within the first paragraph, the author indicates that his present location is situated on a very narrow lot so he probably doesn't have room for much.

Point being, Pete, if he has room for a 20m full wave loop, why waste the wire for a 10m full wave loop inside the 20m loop, when he can feed the 20m loop with open wire line and use it on 17, 15, 12 AND 10m as well?

[w5omr]

I've never had any luck with a 75 meter loop close to the ground, simulation agrees. I bet an inverted Vee works better.

all I did to make my delta loop is close up the bottom of a 75m inverted vee.  Kept the feed point at the apex, changed from coax to open wire line and the changes were phenomenal!

[WA1GFZ]

Now that you have open wire  feed, try going back to an inverted vee?
This will increase the average height of the antenna. A loop may work better if the ends of the inverted vee are too close to each other.
I tried and failed to make a 75m loop work close to the ground.
Then I learned to use antenna simulations so I didn't waste my time.
The bottom of a loop really wants to be a quarter wave above ground or you make an inefficient cloud burner.
As you go higher in frequency interesting things can happen.

[K1DEU]

Tom quite the Gates   Rotation time is never boring

Swinging Gate Side mounts  There are several pre-made One from Max Gain I.E.  IDC  not available until July  nearly $500
    
 http://www.mgs4u.com/IDC-Technology-sidewinder.htm


Custom Metalworks  $230 for Rohn 45g

http://www.arraysolutions.com/Products/cmwantsidemount.htm

With detailed pictures   http://www.arraysolutions.com/Products/sidemountusersguide1.htm

Yea love to have a pair of Log Perodics

[w5omr]

The bottom of a loop really wants to be a quarter wave above ground or you make an inefficient cloud burner.
As you go higher in frequency interesting things can happen.

I get pretty good reports from the East and West coast.  Bottom of the loop is probably 20'.  Apex is closer to 60+feet.

[K1JJ]

Interesting pics / links on the commercial gates, John.

I would say that if you "Armstrong" rotate, the less expensive Array Solutions units look good. Otherwise for rotators, the $500 MaxGain looks FB.

BTW, the log periodic is your best bet. I know you mentioned getting one of those complex, interlaced, Force 12 multiband beams, but think twice. The log periodic is the best choice for many reasons.  If you could possibly stack two, you will have it all, OM.  The 24' boom Tennedyne, once reinforced, is FB. Axe Chuck about having the manufacturer modify it for a little more $. Well worth it.

T

[Pete, WA2CWA]

The title of the article is: "Nested Full Wave Delta Loops for 20 and 10 Meters". Nothing to do with 75 meters. Further, within the first paragraph, the author indicates that his present location is situated on a very narrow lot so he probably doesn't have room for much.

Point being, Pete, if he has room for a 20m full wave loop, why waste the wire for a 10m full wave loop inside the 20m loop, when he can feed the 20m loop with open wire line and use it on 17, 15, 12 AND 10m as well?

Don't know. Maybe he doesn't like the unsightly look of open wire line dangling down; didn't read the entire article. Many amateurs prefer the use of coax feeds over open wire line feeds. In 50 years of hamming, I've never had the urge to use open wire line feeds.

[KM1H]

Point being, Pete, if he has room for a 20m full wave loop, why waste the wire for a 10m full wave loop inside the 20m loop, when he can feed the 20m loop with open wire line and use it on 17, 15, 12 AND 10m as well?
 

 

Many, myself included, have no use for open wire line, or any balanced line plus the aggravation of an antenna tuner.

At one point at another QTH here in town I had 3 80M slopers off a 100' tower that were somewhat effective but not pileup or contest competitive. They got replaced with a Delta Loop that I could switch polarization and it was better than the slopers for DX and stateside; took 2nd place a few times in single band CW. Then I installed a pair of full size cage verticals hanging from pine tree branches and with an extensive radial field. That was often the best as I could show lower angle gain in 2 cardiod patterns as well as a figure 8 broadside where the loop was in a null. It also was configured as a pair of 40M with 2 figure 8 patterns but it wasnt very effective.

With the 2 antennas for 80, a 4el KLM for 40, the 100' tower shunt fed on 160, and the existing 4el W2PV Christmas tree the station won the USA in the next ARRL CW DX contest. Not bad for a 40K Sq ft lot in the lowest part of town

Carl

[Steve - K4HX]

This topic was supposed to be about 10 meters antennas. If you wanna talk about other bands or other subjects, start another thread. Thanks.

[KD6VXI]

I'll throw my two cents worth in here...  Don't know much about 24-30 mhz though... 

The absolute best antenna for 10 meter OMNI I've found, for quality of materials, customer service, support, etc. is http://www.a1antennas.com and the Interceptor 10K.  It AIN'T cheap, but you DO get what you pay for.  Mine failed (it's my 2nd one.  My 1st was stolen while I was relocating 3 states away.  Came back, 2 RF decks, a power supply, antenna and support where GONE), and I notified the mfg.  They designed a new lower section to handle the wind and ice loads I get.  It's NOT uncommon for me to have > 100 mile an hour gusts, 80+ sustained, and 2-3 inches of radial ice load.


The mfg also gives instructions on how to tune the matching network if you want to use it on another band.  It's a 5/8, and performs just like a 5/8 should. 

The matching network is VERY robust, and will handle at LEAST 25kw. 

Performance on both of them that I've owned is <<about>> on par with a 3 element gamma fed yagi from the CB mfg Maco (it's what I had to test it with, installed per instructions years ago)...  The I10K performed just about as well...  Even taking into account pattern skew from the gamma feed on the beam.

The I10k is DC grounded as well.  It uses marine grade stainless for all connections.  Hose clamps are above the quality I've found in most commercial antennas, and something you'd see out in the open ocean... Breeze Hi Torque ALL stainless.  Most 'stainless' hoseclamps at home depot still have a zinc drive screw, and that will rust up..  These don't.

There is another mfg that has an antenna that is very similar...  The build quality isn't the same.

For someone wanting higher power, you supply a connector of choice, they will ship it back that way.  I know of more than a couple running DINs and LCs.  I put an N on mine, due to the weather issues here.

No connection to the company, just a satisfied customer...  I did work with the owner years ago sharing info I had amassed about different GP antennas....  Jay, the owner, took all he could find and made the best antenna I've found.

Mine is currently in 60-70 mile an hour gusts.  The antenna is doing great thus far, and FULLY erect

--Shane
KD6VXI

[WA1LGQ]

I saw that article and wondered about using a 20M loop with open wire line also. So I did a tiny bit of research and also a little bit of antenna modeling and it turns out that a delta loop used at its full wave freq has a better pattern. Mostly lower angles, and according to what I read, lower noise pickup. In real life situations who know? The convenience of multiband use with the open wire line is very appealing.

[Steve - K4HX]

You are correct Larry. When the loop is a full-wave, it produces a nice bidirectional pattern (and with a low take off angle, if it's at the right height). But once you move up to 2x and 3x the fundamental frequency, the pattern falls apart (more lobes and nulls and the take-off angle can be too high). Sure, you can feed the loop with with open-wire and tune it, but the performance will not equal a separate properly sized loop fed with coax.

A dipole is still hard to beat for a simple 10 meter antenna. Other than being omnidirectional, a quarter-wave vertical is not nearly as good as a dipole. Check the simulation results below. Even at the peak take-off angle of the vertical, the dipole beats it by 6 dB!

[K1JJ]

What he said!

It's hard to beat a simple 1/2 wave dipole at 1/4 to 1/2 wavelength high. The horizontal pattern is always a broad figure 8 and the take-off angle is directly controllable by height.  That's why they are so popular. Single band coax fed makes it EZ.

We marvel at a 3el Yagi, but a simple dipole at the same height is within 5db of a Yagi.

Yes, openwire-fed multiband antennas have their advantages with a single antenna covering all bands, but the disadvantage is we lose control of the broad figure-8 pattern on the higher bands which is so important to stable geographic coverage. Personally, from CT I like favoring NE and SW. That's where the population centers are. An antenna with opposite lobes facing NW/SE would be favoring Alaska or the south Atlantic Ocean - with nulls facing the USA and Eu. The difference can be 20db.  That's why I like simple 1/2 wave dipoles, if possible.

Another point: For horizontal antennas, since a wire antenna's take-off angle is based on its AVERAGE height, a simple 1/2 wave dipole is usually easier to get up to a higher average height than a lower hanging loop, extended Zepp, etc. An extreme case would be a tiny 10M dipole vs: a 75M Zepp used on 10M and all bands. Think about it.

The best way to tell if a new antenna is "working" is to have a reference coax fed 1/2 wave dipole mounted at least 1/2 wavelength away at the same AVERAGE height and orientation.  Most of the time we will be disappointed and realize it IS hard to beat a simple dipole.  If it's a new Yagi, then it better show a good 5db or more improvement. DB's are hard-earned.

T

[Steve - K4HX]

You mentioned this system in years past - stacked dipoles. This system really is a winner. You still get the broad lobes of coverage, more gain, and a take-off angle as low or lower than any vertical. See below - 9 dB more gain!

[K1JJ]

You mentioned this system in years past - stacked dipoles. This system really is a winner. You still get the broad lobes of coverage, more gain, and a take-off angle as low or lower than any vertical. See below - 9 dB more gain!

Yep, and take it a step further...

For those who want to dedicate an antenna to one band, (like 10M) consider the popular pair of phased dipoles, but stacked. (Four dipoles, switchable NE or SW)   With one set at 20' high and the other at 40' high, there would be a marvelous uni-directional pattern. Bring two coax feeds into the shack, one from each pair of phased dipoles and add ~120 degrees of coax to one or the other to beam uni-directions.  You'd be channelmaster on 10M ...

Try modeling that, Steve.

T

[Steve - K4HX]

Swine business. Here's a pair of stacked dipoles spaced 0.25 WL and phased at 100 degrees. There's a nice 7 dB gain and a good F/B. This system beats a single vertical by as much as 13 dB! That is huge.  

[K1JJ]

Wow, very nice pattern for west USA work. The TO angle is at about 15 degrees, which is about right. For Eur and beyond, probably 7-10 degrees is better on 10. That wud require another vertical stack. Since there is a small lobe starting to appear in the vertical plane, more height will not help without adding more high angle stuff too.

The equivalent of this wud be a pair of stacked 2el Yagis. If one has a tower, that may be easier to erect. But if trees are the supports, then the wire dipoles may be best.   Though, I've often thought that using a pulley system to raise up two stacked 2el 10M aluminum Yagis using a big tree branch wud work too. Just tie them off to ground stakes and Armstrong rotate them.  Wouldn't that be cool?

T

[KM1H]

I wonder how .25 spacing would be in actual use as thats not a normal spacing for dipoles. Mutuals may require a lot of tweaking to get the phasing to match the software.

If that spacing really works I'll try it on 80 and 160!

[Steve - K4HX]

The stacked dipoles are vertically spaced 0.5 WL. The two stacks are then spaced horizontally spaced 0.25. I don't know if this horizontal spacing is optimal. I just picked it and tweaked the phasing for the best pattern. In reality, it would probably be more practical to just stack a couple of two-element Yagis or Moxons.

[Steve - K4HX]

The stacked Moxons (red line) have ever so slightly less gain and the F/B is not at good when compared to the phased-stacked dipoles (dotted line). But the feed arrangement would be much simpler. I did not tweak the Moxon design. I think you might be able to get better F/B.

[Detroit47]

I've got a 3 element Wilson cb beam that I pruned for 10 it works great.

73 N8QPC

[K3ZS]

Yes, openwire-fed multiband antennas have their advantages with a single antenna covering all bands, but the disadvantage is we lose control of the broad figure-8 pattern on the higher bands which is so important to stable geographic coverage. Personally, from CT I like favoring NE and SW. That's where the population centers are. An antenna with opposite lobes facing NW/SE would be favoring Alaska or the south Atlantic Ocean - with nulls facing the USA and Eu. The difference can be 20db.  That's why I like simple 1/2 wave dipoles, if possible.

T

I added a 16 ft 10M dipole element in parallel (as you suggested a few years ago) to my ladder-line fed 135 ft dipole.    It works great on 10M, the pattern is almost that of a dipole on 10M according to EZNEC and my experience with.

[K1JJ]

Hi Bob,

I almost forgot about that technique for use here. Yes, a good solution to mimick a single dipole pattern for 10M using a big Zepp.  Depending on the freq, the overall pattern will not be a perfect figure-8 due to the Zepp interaction, but will be reasonably close.

Thanks for mentioning it. I'll bet some of the guys may try it too.

T

[kA5WHO]

I added a 16 ft 10M dipole element in parallel (as you suggested a few years ago) to my ladder-line fed 135 ft dipole.    It works great on 10M, the pattern is almost that of a dipole on 10M according to EZNEC and my experience with.




would that work ok scaled for 15 meters.