TopBand: Re: Beverage

[W8JITom@aol.com]

In a message dated 97-02-25 10:23:23 EST, hwardsil@wolfenet.com (Ward Silver)
writes:

<< I would like to know if the design of the 2-wire, reversible Beverage
 depends on "certain assumptions" that may not be widely known. (I don't
 know!)  Such as; ground conductivity between the ends, balance between the
 two wires with respect to ground, symmetry of connections at the
 feedpoint, etc.<<

The biggest design problem is matching impedances without loss or upsetting
balance in the antenna wires.

Remember the wires act like two things. They act like a balanced transmission
line AND as a long wire. Since that transmission line is several hundred feet
long
and supported in the air, if you aren't very careful in transformer designs
at both
ends of the antenna performance will suffer.

Conductor spacing and balance to ground along the antenna is critical.

Simply grounding one wire at the far end almost gurantees poor performance,
as
does a transformer with improper design.

The antenna itself should use wires spaced as close as possible, and
hopefully
have a Zo matching the reflection transformers design impedance. A properly
designed system will have no impedance mismatces, and near perfect balance.

That's why I use 450 ohm line twisting it along it's length, and use well
designed
transformers at BOTH ends. 

I've never had a system that was not repeatable, in Sylvania Ohio over
wet balck marsh, in South Amherst Ohio over midwest clay, and in Georgia over
rocky poor soil they all worked the same.

When NI8G duplicated my system exactly, he obtained the same results.

73,
Tom   

--
FAQ on WWW:               http://www.contesting.com/topband.html
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Problems:                 owner-topband@contesting.com
Sponsored by:             Akorn Access, Inc. & N4VJ / K4AAA