johnwigney@att.net wrote:
> ...If I had to do things over again, I would
> have evaluated Jim's copper tape for the VOR and COM and transponder. No
> reason
> to expect that they would not work.
> ....
Actually even Jim weir does not recommend a copper-tape dipole for the
transponder. It is highly unlikely the thing will come out peaked
between the xmit and receive frequencies, and the equipment to tune it
is not within easy reach.
A dipole for the xponder wastes a theoretical one half of the power
radiating above the aircraft, meaning that a 1/4 wave antenna will
have more gain in the desired direction. A dipole is also technically
illegal in the U.S. even on a homebuilt, per strict interpretation of
Part 91 and the xponder TSO, in lieu of a TSO or radiation field
testing. Not that it's not a usable product, Archer's xponder antenna
sure looks like a dipole.
Regards,
Fred F.
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