Re: Flight Report

Rick Hole

Transponders transmit high power pulses at a low duty cycle. Antenna heating is unlikely. If the antenna installation, as in Mike's case, gives good range you can be sure the antenna is working with a sufficiently low SWR.
Determining gain at 1 GHz accurately requires expensive gear. But an easy test is to compare range to another antenna. If the antenna works at longer range (using the same transponder and coax) it has more gain. True, you don't get a number in decibels.
Coax: Mike is an experienced amateur radio "ham" with a lot of antenna experience. He knows that although RG400 is lower loss and recommended for 1000 GHz and RG58 is nearly a dummy load at that frequency, at line lengths of 6 feet or so it doesn't make much difference. What does make a difference is the quality of the braid shield. What I call junk is about 60% shield. I recommend using full shield coverage. That applies to our VHF antennas too.

Rick Hole
Retired professional engineer
50 year Amateur Extra
Velocity, electronics systems retired

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