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Topband: Beverage Antenna

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Subject: Topband: Beverage Antenna
From: "Walter Schulz" <>
Date: Fri, 20 Aug 2004 20:38:38 -0400
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I thought to jump in here with my two cents worth of nonsense, you see I live 
in the woods, and don't see to many people these days.....thank here 
goes it!!!

The single wire Beverage works on the theory of wave front tilt, consulting the 
books of 1915 to 1917 by Prof. Zenneck you might of heard of something called 
the Zenneck Wave.
On ELF, VLF, and LF, that's all the frequencies or wavelengths below 500 Kcs or 
the medium wave broadcast band the wave front travels outward from the antenna 
transducer (vertical monopole) along the earth's surface and the bottom side of 
the ionosphere. There is no skywave that is received. The earth is a 
dissipative medium, which means that its something like a resistance when 
compared to the air, therefore the wavefront as it travels forward and outward 
starts to tilt forward. Depending on the soil it will tilt forward to 
approximately 1 to 10 degrees, over salt water and salt water marsh it remains 
perpenicular to the earth's surface. What does this mean? As the wavefront 
leans or tilts forward it cuts across the Beverage antenna inducing a voltage 
in the wire. This voltage builds in amplitude as it travels to down the wire to 
the receiver. Signals coming from the opposite directions do the same, build in 
amplitude with one big difference. Upon reaching the terminating resistance the 
voltage is dissipated across the resistance. No standing wave reflected back to 
the receiver, if the terminating resistance matchs the surge impedance of the 
Beverage single wire. Here is where it gets interesting. The resistance is 
grounded and the return path goes thru the earth back to the receiver side 
ground to complete the path. Therefore, if we treat the Beverage as a single 
wire transmission line we find the actual surge impedance impedance of the 
antenna as approximately 470 ohms. But we must also include the dissipative 
resistance throught the ground. Tom, W8JI, as a pretty good handle on 
explaining it to you. Tom is right about the wire under the Beverage is wrong, 
not necessary, a no-no, Mr. Misek as it wrong.........

Here's the catch 300 Kcs to 3 Mcs is where transitional propagation takes 
place. Waveguide mode theory is no longer valid as we apply in ELF, VLF, and 
LF. At 160 meters the ground wave from the transmitter only travels 
approximately 100 miles from the monopole, and then vanishes from the surface 
of the earth thru absorption. We depend on skywave, chordal ducting, ionosphere 
tilting, and ducting South to North. You are receiving the sky wave which is a 
tumbling wave front arrivaling at the antenna and traveling the antenna axis. 
You are no longer receiving just a ground wave or E Field, but an ellitpical 
wavefront. You do not need another wire under a single wire Beverage, it does 
absolutely nothing for the antenna system.

There is another way to overcome dissipative ground loss in Beverage antennas, 
however, its a little to complicated for me to explain to you presently.

Why multiple wire Beverages antennas, we can add another two wires to a single 
wire Beverage, what this does is decrease the velocity of propagation on the 
antenna. It also smooths out the impedance bumps in the antenna. Namely it 
makes the antenna appear electrically longer than it really is, but at a cost, 
the cost is less gain.

Do not confuse the multiple wire Beverage with the 2 wire beverage bi 
directional antenna system. It works on a different principle than what I have 
described. It is not to well known. You will do fine with a single wire in 
multiples of halfwave 3/2 will work just fine. Approximately 800 feet on 160 
meters. I would go by W8JI webpage it describes much of the basics and you 
won't go wrong.

I use 3 Bi directional Beverages here, NE-SW, SE-NW, N-S, I used RG59 to feed 
them. Reflection transformers and on each end 7 ground rods, 8 ft long in HEX 
Configuration tied together with no. 8 AWG copper wire.

Good Luck,
Master Radio Electronics Officer
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