Dear Mac,
As many radials as possible will be best so try for 8 elevated radials
as a minimum.
If you go much over .375 wavelength the matching at high voltage points
with major reactance is a problem. At 0.25 wavelength, with no losses the
impedance, Zant = 36 ohms. With 0.29 wavelength, Zant ~= 50 + 100j, so a
series capacitor in the 800 - 1000 pfd range will give you 0j at the feed
point. With 0.32 wavelength the impedance of the vertical is Zant ~= 100 +
200j, which requires an L-network tuner at the feed point or at the
transmitter, and the value of series capacitors goes down, so the voltage
rating required is much higher.
73 George K8GG
----- Original Message -----
From: "py2cw160 "Mac"" <py2cw160@terra.com.br>
To: <topband@contesting.com>
Sent: Tuesday, July 16, 2002 10:55 PM
Subject: Topband: Balloon vertical antenna
> Hi folks
> I am consideering a balloon for a 160 vertical. Questions...
copperweld wire? thickness? balloon volume to 1/2 or 5/8 wave vertical? What
about 4~8 elevated radials in 30 ft tower?
>
73,s Mac
>
>
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