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Author Topic: Beverage loop?  (Read 12282 times)
KB1TXK
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« on: December 22, 2011, 05:44:00 PM »

My little plot of the world is 150' wide x 250' long. I was thinking of buying 2x spools of 500' 14ga solid wire and making a loop antenna about 6.5' - 7' up. I can just use paracord and trees to 'mount' it. There will be a gap where the driveway enters, needless to say.

I'm just using it to listen, so I assume 80' of rg-8 would make a good feedline (~$25) . If I want to splurge, lmr-200 (~$50).

I have a crap-load of flooded rg-6. Would that work just as well as a feedline?

A less-costly version of this would be 800' of used coax of various lengths, connected w/ f-connectors and couplers. I dont like the idea of introducing water into the antenna however, and i cant vouch for the jackets on all the coax bits. Hence me wanting to use a solid wire instead of coax shield.

I also wonder if using the wire as main element and junk coax as counterpoise (grounded every-so-often w/ 8' stakes) would add a worth-while benefit.

There is little-to-no chance of people interacting w/ this antenna. Animals will just have to trip over the counterpoise. The (beverage) circle of life and all...

I guess my main question is: I dont really see much about beverage loop antennas. Is such a thing even possible?
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WX7G
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« Reply #1 on: December 23, 2011, 07:36:58 AM »

What frequencies are you interested in listening too? Do you want omni-directional coverage or are you aiming at a particular part of the world?
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KB1TXK
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« Reply #2 on: December 23, 2011, 07:41:36 AM »

as wide a range of freq as possible, and as omnidirectional as possible.
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W1AEX
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« Reply #3 on: December 23, 2011, 08:52:34 AM »

RG-6 works very well for an RX antenna system. It's cheap, exhibits very low loss across the HF spectrum, and decent stuff will last for decades outdoors. If your "flooded" RG-6 isn't contaminated by water ingress it should work fine. If you suspect it is contaminated, dump it and buy new stuff. Even the 100' contractor spools at places like Home Depot and Lowes (15 to 20 bucks) will work just fine. I use +200 foot runs of RG-6 for my two broadband HF receive loops parked away from the house and it works great.
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AA4HA
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« Reply #4 on: December 23, 2011, 12:19:21 PM »

A beverage is a near ground mounted, long wire antenna that is terminated at the end with a non-inductive resistor (usually 450 ohms to ground) and uses a 9:1 balun to convert the 50 ohms of coax to 450 ohms of antenna. Using 75 ohm to 450 ohm may be more like a 6:1 balun.

A beverage is low efficiency but very directional at lengths that frequently exceed one full wavelength (hundreds to thousands of feet long).

What you are working with is more like a non-resonant loop antenna. They can be decent antennas and I would suggest some sort of antenna tuner (tune for a peak in the signal or static levels). This can still work quite well for a SWL receiving antenna.

A straight, long wire beverage is sort of a specialty antenna. As if you were into monitoring broadcasts from a specific region of the world and the directivity is off of the end of the antenna (like pointing an arrow).

Hope that helps some
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
WX7G
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« Reply #5 on: December 24, 2011, 07:43:29 AM »

Since you want omni-directional a Beverage antenna is not for you.

A wide band terminated dipole or vertical would be good. I've build both and they work well - about 6 dB down from a resonant dipole.
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KAPT4560
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« Reply #6 on: December 26, 2011, 04:30:58 AM »

 There are many ideas on Google if you type in: 'am dx antennas' or similar searches. I have an inverted 'L' with an E-W attic longwire and rely on antenna tuning to pull a DX catch out of the mud. At the same time, you don't want to overload a sensitive receiver.
 The National Radio Club is an excellent information source for this fascinating hobby:  http://www.nrcdxas.org/catalog/books/index1.html
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W0BTU
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« Reply #7 on: December 31, 2011, 02:31:57 PM »

This reminds me of an antenna someone asked me to model for him. It was a low U-shaped wire mounted on top of a non-conductive fence. I uploaded the pattern plot and EZNEC files to http://www.w0btu.com/files/antenna/Fence-tenna/ if you want to look at the details. Rather strange pattern with lots of low-angle lobes, but he had fun with it. I worked him on 40 meter SSB in May, and he was transmitting on it.

If you're going to feed this with RG-6, wind a simple 6.25:1 broadband matching transformer with a single Amidon BN-73-202 ferrite core as shown at
 http://www.w0btu.com/Beverage_antennas.html#Beverage_Antenna_Transformers. It will work from ~100 kHz to 30 MHz.

When you're tired of that and want to try something better, look at the different limited-space antenna suggestions at
 http://www.w0btu.com/Beverage_antennas.html#If_theres_no_room_for_a_Beverage.
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W0BTU
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« Reply #8 on: December 31, 2011, 02:43:54 PM »

RG-6 works very well for an RX antenna system. ... If your "flooded" RG-6 isn't contaminated by water ingress it should work fine.

"Flooded" does not mean it was exposed to water. It means it's impervious to contamination by water. :-)

Flooded coax has a sticky "flooding compound" impregnated in the outer braid. You can nick the outer jacket and leave it submerged in water and it won't hurt it at all. It's suitable for direct burial in the earth.

Commscope flooded quad-aluminum-shield RG-6 coax is all I use outdoors here. It's great stuff.
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W1AEX
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« Reply #9 on: January 01, 2012, 07:25:45 AM »

"Flooded" does not mean it was exposed to water. It means it's impervious to contamination by water. :-)

I've never heard that term. Thanks for the explanation! The run I have used for so many years out to the tree line is just as you described with sticky-goopy stuff throughout the braid and shield. Guess it's "flooded".

:O)

Rob W1AEX
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W0BTU
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« Reply #10 on: January 27, 2012, 11:40:00 PM »

Since you want omni-directional a Beverage antenna is not for you. ...

This is a true statement. :-)

However, I think if he knew just what a directional antenna could do for his listening pleasure, he would embrace the idea of a directional antenna. Seriously.

After all, directional antennas are for getting rid of noise and unwanted signals so we can hear the desired signal (the rare ones, etc.).

I've used omni-directional antennas for many years. But the real fun came when I installed my Beverages.
http://www.w0btu.com/Beverage_antennas.html
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