how about this for a 160 meter ant?

[N3DRB The Derb]

besides looking cool as all hell, how do ye masters of top band think it would perk? It would fit on the property no problem.

[K1JJ]

Hola Tim -

It looks "radio romantic," but a simple 'T' fed against ground will do basically the same thing without the mechanical complications of that design.

You can also tie your exisiting openwire feeders togethers and feed that as a 'T' too.  You probably don't have the radial field down yet, but more like 100' long minimum radial length wud be in order for 160M.

Either way, it wud be a great antenna for 160 M cuz it will grab both a vertical and horizontal component for you to work close in and DX.  The only thing to watch is keep it as far away from objects like the house, etc or the low angle energy will be partially wasted through absorption.

T

[W1VD]

Derb

If it's a good fit for the support structures you have available it should work fine. There's little advantage to that top loading arrangement vs. an inverted L or T, though.

Hard to see in the pix but that's the arrangement in use here on 137/500 kHz...

http://www.w1vd.com/XNStxantenna.html

[W2PFY]

Yo Derb, I wike it

I actually seen one similar but it was for WBZ In Springfield, MA on top of the old Westinghouse building. I don't know if my facts are correct but I understood they used it for a simulcast for their station in Boston. Very Old BUZZARD  

[N3DRB The Derb]

I'm thinking it would make a excellent antenna for a certain broadcast TX I am looking to buy.  

and the mo' buzzard teh better. I believe this one will have to do as I can probably manage it better than other alternatives.

[W2PFY]

I'm thinking it would make a excellent antenna for a certain broadcast TX I am looking to buy.  

and the mo' buzzard teh better.

buy?? Don't they still give them away. Get hold of Paul, he must have about 50 of those hanging around

[WU2D]

Why wouldn't this outperform the L or Tee?

Hey this is a pretty much the standard Marconi setup of the 20's. Those old timers wanted to get current into the antenna. Perhaps the antenna had other advantages as well like stability to oscillator pulling, but why go to all the fuss and complexity?

All grounds being equal, the gigantic top hat effect of the three wires should provide more antenna current as measured at the feed than that achieved in a single T wire. Tom can you model this, especially in respect to vertical polarization gain? We just want to see a single wire Tee vs the three wires as spaced.

But a better ground system is where much of the easy gain "gains" probably lie, so it may also be interesting to compare a poor ground vs good ground with the monster.  

Mike WU2D

[k4kyv]

The mult-wire flat top should give more top loading than would a single wire, because multi-wires would provide more capacitance to ground.  Since the horizontal section is fed at the midpoint by the vertical wire, there should be very little radiation from the flat top since each half would cancel the radiation from the other. The 50' radials may not be ideal, but they certainly would beat a hammy hambone ground system consisting of a couple of 8' ground rods and no radials.  I'd lay down as many radials as possible, making each one as long as possible. If you could lay down 120 quarter-wave radials, that antenna would be almost as good as a full size quarter wave vertical.

Feeding the flat top at one end instead of at the midpoint would make the antenna into an inverted-L, and the horizontal section would radiate.

[ke7trp]

Looks neat but to me thats alot of effort.   I put up a resonant inverted L in a few hours out of junk parts.  Its about 55 ft before it kinks over. The end has a long Rope leader to the Fence.  I put out 4 radials so far.  Walked in the house and its 50 ohms and flat at 1885   It really talks well for what it is.  I can plug it right into my Transmitters with no tuner and match it nicely.  I had planned on putting up a ton of  radials but four elevated radials got me the performance I wanted. 

Clark

[W8ACR]

Hi Derb,

I think there may be one advantage to the three wire design over a single wire.....I think it will have a broader bandwidth. I once had a single wire inverted vee which had a vertical component of about 40 feet and a horizontal component of about 90 feet or so. With a single wire, the 2:1 bandwidth was about 25 kHz which is typical. I then converted it to a three wire system using hardware store PVC as a spreader - about 4 feet as I recall. The three wires went all the way from the ground to about ten feet from the far end. It was insulated from ground at the near end and fed with coax through a simple balun and a tuning network at the antenna base. The bandwidth almost doubled to about 45 kHz. It withstood howling North Dakota winds. The antenna that I built was based on a design that can be found on page 59 of the book "Practical Wire Antennas" by John Heys G3BDQ. I can loan you the book, or photocopy a few pages if you'd like. I'd say that if you are going to use a single frequency only, then there is no big advantage to using three wires, but if you want to move around the band a bit, then the three wire design may be advantageous. One last thing, 120 foot radials are a big advantage over 50 footers. I'd put down as many as you can and make them as long as you can (up to 120 feet.) My anternna had about 80 radials all of which were 120 feet in length. The feedpoint impedance was quite good at about 30 ohms. That was a great antenna.

Good luck,

Ron W8ACR

[Jim, W5JO]

Derb, a lot of Non-Directional Beacons used that type of antenna with great success, some of them went out of service just in the past 10 years.  One thing for sure is the neighbors will know what you are doing.  Put as many radials down as possible, as long as possible and it will work fine.  Installed correctly and loaded it will make you the station on 160.

[N2DTS]

I used to do work at the beacon sites, they were not high, about 30 feet up, not long, about 50 or 75 feet long, and were on low frequency I think, modulated by some tone or CW.

I dont know what they had for a ground system under the antenna, they were typicly around the outer marker for aircraft approch, and were likely for very short range.

They were very well built tho, using telephone poles...

Brett

[N3DRB The Derb]

I did some reading and what I found is that having longer radials than the area under the flat top isnt going to get you much. The fact that it has the flattop changes the game a bit from what you would expect from a 1/4 wave vertical.

having to only lay down this many radials and having them be shorter is a big + for me. There's some loss I'm sure but I dont think it will amount to enough to trade the extra work involved.

BTW, I would go with the 3 wires anyways. How could you not?   It's kool as all hell!

[N2DTS]

Yes, and you can hang a LOT of laundry on it to dry!

Brett

[WQ9E]

Derb,

Give strong consideration to Don's suggestion of setting it up as an inverted L.  They are easy to feed (make it slightly long electrically and tune with a series capacitor) and work very well. 

I modified my Hy Gain Hy Tower to work as an inverted L using a wire from an extra stub on top of the main tower assembly to my Rohn 55G.  I use a tap switch from a BC-375 at the base to switch in series capacitors made from pieces of RG-11 and this gives me good coverage of 160 without having to use an antenna tuner.   Now I just need to run some low loss coax out to the barn "shack" so I can also use that antenna with the vintage gear in the house.

[N3DRB The Derb]

heres the original page which includes some info. Anyone see anything weird with the ground resistance claim or the bandwidth claimage? it looks OK to me.

The T config would fit much better on my land than a L would. I have a brand new TU-10B ( covers 75 meters ) tuning unit from a BC375 I am getting ready to molest for the caps and coils it contains. 


http://www.pcsystems-ss.co.uk/g7lrrweb/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=41&MMN_position=61:37

[K1JJ]

The T config would fit much better on my land than a L would.

Derb,

Glad you're looking at a regular single wire 'T' rather than that 3-wire monster.  Just to point out a few things... You would need a tower in the center to support that thing and some very strapping trees on the ends. If you get ice, it could weigh in the hundred's of pounds.   I once had one up in the late 80's for 75M and could not believe the pull it took to hang it unsupported in the middle.  Considering the trouble you've had with antennas breaking cuz of the weak trees on the ends, think it over...

You mentioned a tower may be in the plans this spring. Nothing wrong with a shunt fed 50'-60' tower for 160M with a good radial field under it. That wud be a system that will last for years and years and worth putting the money into for a great copper radial system. You cud use the horizontal top of your 75M inv vee dipole as a "coupled" 'T' - just like Don does using the feedline run up the tower as a magnetic coupling technique.  IE, by feeding the tower, the feedline and dipole become part of the system to add top capacitive loading  - making a 60' tower close to a 1/4 wave on 160M, etc.

T

[Steve - WB3HUZ]

Ground resistance is completely dependent on the soil conductivity and the number of radials used. It has zero to do with the antenna.

heres the original page which includes some info. Anyone see anything weird with the ground resistance claim or the bandwidth claimage? it looks OK to me.

The T config would fit much better on my land than a L would. I have a brand new TU-10B ( covers 75 meters ) tuning unit from a BC375 I am getting ready to molest for the caps and coils it contains. 


http://www.pcsystems-ss.co.uk/g7lrrweb/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=41&MMN_position=61:37

[k4kyv]

I did some reading and what I found is that having longer radials than the area under the flat top isnt going to get you much. The fact that it has the flattop changes the game a bit from what you would expect from a 1/4 wave vertical.

Where did you read that, and when was it published?  Since the radiating part of the antenna is the vertical wire, I would say that you need a good radial system, preferably 360° round the base of the wire just the same as you would for a vertical tower.  All the flat-top does is add capacitive  loading to the top of the wire.

In the early days of radio, they thought you needed to put the counterpoise directly under the flat top because the antenna was thought of as a giant capacitor.  One plate was the ground system/counterpoise, while the other plate was the flat top.  It was thought that the radiation was caused by the displacement current between the plates of the capacitor, and that the vertical wire was merely the feedline to feed rf to the top plate of the capacitor.  Later, the theory was refined to state that the radiation was caused by the rf current in the vertical conductor.

[WA3VJB]

Actually Terry, it's been a while since anyone rang the bell and left one on the doorstep.

The days may be about done, of them getting tossed by radio stations.

I know of at least two that have been "rescued" but are sitting around awaiting attention, that's probably the way these will most likely find homes.

Yet, just today, I worked a guy on 40m AM who knows about an abandoned radio station site where at least one and possibly two Gates kilowatts are sitting around.

ROAD TRIP !!!

As for Derb, he got my very first BC transmitter, a GE 1/4 kw  that I got 17 years ago for a dollar a watt.  He's using the front door emblem for his avatar.

I'm thinking it would make a excellent antenna for a certain broadcast TX I am looking to buy.  

and the mo' buzzard teh better.

buy?? Don't they still give them away. Get hold of Paul, he must have about 50 of those hanging around

[W1VD]

If you get ice, it could weigh in the hundred's of pounds.   I once had one up in the late 80's for 75M and could not believe the pull it took to hang it unsupported in the middle.

You're not kidding! If you're planning a big top hat you might want to avoid this stupid human trick.

During an unexpected ice storm a couple years back I went out at 2 am to lower the 10' X 100' 3 wire top hat. The ends are hoisted with rope and pulleys (line and blocks actually) from the base of each tower. It was hard to tell how much ice was on the wires up at 90' but knew it was going to be heavy. Made a few wraps of line around one hand while loosing the last knot with the other. You guessed it. Luckily the wraps around my hand weren't hitches. Got pulled up off the ground to about 15' before the wraps came loose and I managed slide down the rope to terra firma.

Now back on the ground with the support line still going up (sliding quickly through my hands) comes the shower of big ice chunks from 90'. The rope was shedding its ice as it passed through the pulley...no time to let the antenna go and get out of the way. Now I know why they make hard hats. At least I was wearing heavy leather gloves. No permanent damage to the antenna...or stupid human. 

Now, any time there's even a remote possibility of ice the tophat is lowered well in advance.     

[W8ACR]

Hi Derb,

Two more cents' worth. I was reading my previous post and I need to clarify a couple of things. First, I used an UNUN at the base of the antenna, not a balun of course. The second thing is this. As I understand it, a vertical antenna is a resonant system. When tuning a vertical antenna system, there are two objectives: one must obtain resonance, and one must match the feedpoint impedance. A 1/4 wave vertical radiator over a perfect ground will have a feedpoint impedance of about 36 ohms. When the radiator is too long or too short, it must be brought back to resonance with a capacitative or inductive element. Once this is done, then the feedpoint impedance must be matched. For example, a 30 foot vertical radiator over a perfect ground will be resonant near 40 meters, and will have a feedpoint impedance of about 36 ohms at its resonant frequency. To use this antenna on 160 meters, one would have to add a coil at its base, or a top hat. The proper value of loading will make it resonant, but now its feedpoint impedance will be found to be very low, say 5 ohms or so. If the feedpoint impedance is higher than this, then there is loss in the system, such as a poor ground. To use this 5 ohm antenna with a 50 ohm feedline, one would have to use an impedance transformer such as an UNUN.

In lieu of a coil and an UNUN, one may tune the antenna with a complex system containing both inductance and capacitance, but I found the coil and UNUN to be simpler for my setup. I also found that an antenna analyzer was most helpful when making adjustments.

73, Ron W8ACR

[K1JJ]

If you get ice, it could weigh in the hundred's of pounds.   I once had one up in the late 80's for 75M and could not believe the pull it took to hang it unsupported in the middle.

You're not kidding! If you're planning a big top hat you might want to avoid this stupid human trick.

During an unexpected ice storm a couple years back I went out at 2 am to lower the 10' X 100' 3 wire top hat. The ends are hoisted with rope and pulleys (line and blocks actually) from the base of each tower. It was hard to tell how much ice was on the wires up at 90' but knew it was going to be heavy. Made a few wraps of line around one hand while loosing the last knot with the other. You guessed it. Luckily the wraps around my hand weren't hitches. Got pulled up off the ground to about 15' before the wraps came loose and I managed slide down the rope to terra firma.

Now back on the ground with the support line still going up (sliding quickly through my hands) comes the shower of big ice chunks from 90'. The rope was shedding its ice as it passed through the pulley...no time to let the antenna go and get out of the way. Now I know why they make hard hats. At least I was wearing heavy leather gloves. No permanent damage to the antenna...or stupid human.  

Now, any time there's even a remote possibility of ice the tophat is lowered well in advance.      

  Wow, that's quite a message!

It's amazing how quickly things can get out of hand and dangerous.    The problem with ice is it sometimes sneaks up on us when least expected, especially at night and at the higher altitudes where you live there, Jay. I have the same problem here too. The WX-man says rain, but doesn't mention what will happen 800 - 1200' higher in elv....   I've woken up and have seen my old 40M Yagi with its elements almost pointing at the ground. If the wind starts, then the real worry begins.

T

[W2PFY]

Never heard of a UNUN so I looked it up. Don't know if this is exactly the one used?

http://www.k0bg.com/unun.html

[KB2WIG]

"I am writing in response to your request for additional information, for block number 3 of the accident reporting form. I put 'poor planning' as the cause of my accident. You said in your letter that I should explain more fully and I trust the following detail will be sufficient. I am an amateur radio operator and on the day of the accident, I was working alone on the top section of my new 80-foot tower. When I had completed my work, I discovered that I had, over the course of several trips up the tower, brought up about 300 pounds of tools and spare hardware. Rather than carry the now unneeded tools and material down by hand, I decided to lower the items down in a small barrel by using the pulley attached to the gin pole at the top of the tower. Securing the rope at ground level, I went to the top of the tower and loaded the tools and material into the barrel. Then I went back to the ground and untied the rope, holding it tightly to ensure a slow decent of the 300 pounds of tools."

"You will note in block number 11 of the accident reporting form that I weigh only 155 pounds. Due to my surprise of being jerked off the ground so suddenly, I lost my presence of mind and forgot to let go of the rope. Needless to say, I proceeded at a rather rapid rate of speed up the side of the tower. In the vicinity of the 40-foot level, I met the barrel coming down. This explains my fractured skull and broken collarbone. Slowed only slightly, I continued my rapid ascent, not stopping until the fingers of my right hand were two knuckles deep into the pulley. Fortunately, by this time, I had regained my presence of mind and was able to hold onto the rope in spite of my pain. At approximately the same time, however, the barrel of tools hit the ground and the bottom fell out of the barrel."

"Devoid of the weight of the tools, the barrel now weighed approximately 20 pounds. I refer you again to my weight in block number 11. As you might imagine, I began a rapid descent down the side of the tower. In the vicinity of the 40-foot level, I met the barrel coming up. This accounts for the two fractured ankles, and the lacerations of my legs and lower body. The encounter with the barrel slowed me enough to lessen my injuries when I fell onto the pile of tools and, fortunately, only three vertebrae were cracked. I am sorry to report, however, that as I lay there on the tools, in pain, unable to stand and watching the empty barrel 80 feet above me, I again lost my presence of mind. I let go of the rope..."