|Subject:||[TowerTalk] Re: TowerTalk Digest, Vol 18, Issue 3|
|From:||Bill Fuqua <email@example.com>|
|Date:||Wed, 02 Jun 2004 13:44:33 -0400|
At 12:00 PM 6/2/2004 -0400, firstname.lastname@example.org 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.
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
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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