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Re: Topband: Two Wire Beverage Query...

To: "Ford Peterson" <>, <>
Subject: Re: Topband: Two Wire Beverage Query...
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Fri, 20 Aug 2004 12:04:43 -0400
List-post: <>
>>Well, it comes with some merit at this link...>>

Several of the diagrams describe a ground return line
between the ends.>>

I can describe anything I like, but even if I tell you
something is wonderful if it doesn't make the least bit of
sense then it probably is not a good idea. Why would a very
long wire laid against a lossy media provide a low
resistance RF connection??

The radiation resistance of a Beverage is down around one
ohm. The vast bulk of the resistance you measure is related
to losses. Losses increase when a conductor is lowered
closer to the lossy media. If I have a BOG, the surge
impedance is pretty high even though conductor spacing to
earth is almost zero.

The only reason a Beverage works is the relatively high loss
in the media around the wire. The reason a Beverage receives
signal is the very high distributed loss, and that loss is
caused by coupling to the media around the wire. Even a
dipole has very high feedpoint resistance when brought
within small fractions of a wavelength of earth. Where does
that resistance come from? From loss.

Suddenly just because someone says the very same
configuration has a low loss resistance it changes? I don't
think so.

Several respondants to the query indicate that would be a
good idea to run the extra wire and others agree with Tom.
Geez guys, I'm not an engineer.  I'm an accountant.  It
appears that there is some confusion as to the best approach
to Mr. Beverage's work.  I'm not trying to start WWIII in
some debate, I'm trying to build a better beverage...>>>

I think it is pretty obvious who is correct Ford.

If it was a low loss connection, the antenna would quit
working. If it is a very high resistance path (which it is),
it doesn't do any good. Why install something that can't
work, but if it does work would make the antenna quit
working? Are you building a loop antenna or a Beverage?

We have to watch what we read. Can you imagine a core
material that has "a good ohmic ground for the cores and
acts as a Faraday shield" yet still works as a transformer?
I sure can't. That's another glaring contradiction.

<<<I studied your 'ground measurements' page with great
interest.  I wish you had described your test setup a bit
better.  I guess I'm a bit confused as to how you measured
the impedances reported in the table.>>

I have a short loaded vertical with almost zero radiation
resistance. I resonate it with an inductor of known ESR and
measure the feed impedance. What isn't coil ESR and
radiation resistance is ground resistance. This also agrees
with how the same rods behave when terminating a Beverage.

Also, re: 'surge impedance.'  How does one measure this?  I
was effectively able to measure the characteristic impedance
of the two wires to be in the 680 ohm area.  The data I
collected is very solid using a sweep of 1 to 8 MHz.  And a
sweep of a single wire over ground came in at about 450-470
ohms with the data not nearly as convincing in the same
sweep.  But how do you measure to see whether the surge
impedance is 300 or 600 ohms?>>>

You already measured the effective surge impedance if you
paralleled the wires and swept them. You did measure the
parallel feed resistance when they were terminated to
produce a flat response, didn't you? Just deduct the ground
connection resistance and you have the surge impedance.

73 Tom

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