Richard Harrison wrote:
Cecil, W5DXP wrote:
"The 180 deg. phase reversing coil is the tricky part."

For UHF, you might prefer to use a 1/4-wave short-circuited stub in
place of a coil to reverse the phase. My 19th edition of the ARRL
Antenna Book shows such an antenna, "the super J-pole on page 16-25. At
other frequencies, this might be called a "Franklin Antenna". It`s a
1/2-wave in-phase with another 1/2-wave, one mounted directly over the
other.

The stub is a good idea and can be mechanically self-supporting at
920 MHz. However, making the bottom section 1/4WL (as Kraus suggests)
instead of 1/2WL would make for a low feedpoint impedance

The super J-pole is designed for 144 MHz, but can be scaled for any
frequency with proper mechanical allowances. Gain is about 6 dB over a
1/4-wave whip.
--
73, Cecil http://www.qsl.net/w5dxp


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