There seems to be misunderstanding about terminating these antennas properly.
The
purpose of the terminating resistor is to absorb energy propagating down the
wire
from the rear (for good F/B ratio). The SWR is determined by the relative match
between
the antenna impedance (usually around 500 ohms) and whatever the matching
transformer
is designed for (usually 450 ohms). A properly terminated Beverage will be
aperiodic,
that is, exhibiting NO resonance effects. The proper way to adjust the
termination is to
sweep across the bands of interest and adjust the termination for minimum
VARIATION
of the SWR over that range. This will give the best F/B ratio and will also
take care of
the resistance of the ground rod or whatever your using as ground at the
termination. If
the resulting SWR at the input makes you nervous, wind a wideband transformer to
match the impedance at that point. Anything under 3:1 and the Rx probably won't
know the difference anyway!
73, Merry Christmas and GL
Roger
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|