At 12:00 PM 6/2/2004 -0400, towertalk-request@contesting.com wrote:
I expect most antennas would fail by arcing limits for low
duty cycle modes and by heating on high-duty modes like CW.
The failure points I've found were always heat related in
the coil. Away from coil self-resonance near the finger
stock, otherwise in the area of maximum voltage where the
coil is self-resonant.
73 Tom
It turns out that the shorter an antenna is relative to a
wavelength is, the higher the Q of the resonant antenna system (antenna,
transmission lines, coils, inductors and tuner) must become to effectively
radiate RF energy. And in achieving that higher Q using coils and/or
capacitors there is a good chance of increased losses due to the higher AC
currents and voltages involved. Also, along with that comes narrower
antenna system bandwidth. If a electrically short antenna is broadband then
it must have a lot of loss. Screwdriver antennas have a lot of inductance,
I suspect that there is appreciable loss in the inductor along with high
currents and voltages.
73
Bill wa4lav
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