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Old March 8th 08, 04:21 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
Posts: 588
Default Antenna physical size

Art wrote:
"---my antenna is a full wavelength which meets Maxwell`s requirements,
it is just that the volume is small despite the wavelength."

In 1949, I worked at the KPRC-KXYZ broadcast plant. Another operator
there, J.L. Davis, W5LIT had a new 1949 Ford in which he installed a
surplus ART-13 and a PE-103 dynamotor. For an antenna he wound wire turn
by turn on a bamboo pole until it was resonant on a slice of the
75-meter band.

When J.L. modulated, Q in the coil produced a tip corona on the first
good peak and modulation became loud without a receiver.

The 20th edition of the ARRL Antenna Book on page 16-13 says this about
continuously loaded antennas: "The general approach has been to use a
coil made from heavy wire (#14 or larger), with length-to-diameter
ratios as high as 21. British experimeters have reported good results
with 8-foot overall length on the 1.8- and 3.5 MHz bands. The idea of
making the entire antenna out of one section of coil has been tried with
some success."

Art`s antenna containing a "full wavelength" of wire would likely
feature a greater loss than J.L.`s 1/4-wave resonant coil from simply a
greater length of wire while both have peactances balanced to zero.
Art`s lower Q would probably kill the corona, increase the bandwidth,
while losing the gain that a fullwave straight conductor enjoys.

Cecil can probably report on results of continuously loaded mobile
antennas versus a bug catcher loaded whip in the California shoot-outs.

Best regards, Richard Harrison, KB5WZI


 
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