Request RF/Groundplane info

Hi, All;

I'm trying to decide on where to place the transponder antenna. This is a "regular" pre-ADSB small monopole antenna. This is going on a Zenith Cruzer, all aluminum.

My question is: How close to the edge of the structure may I place the antenna? IOW, I don't know if I need to have a minimum distance in each direction from the mounting hole, or is having plenty of room in the other 3 directions sufficient. I *know* a center-placed antenna would be better, I just don't know how much I lose with an edge-mounted antenna.

Thanks for any info you provide!

Attachment 8335

A quick calculation would tend to indicate that 8 cm (just over 3") would be fine.

Thank You, Ron; may I ask how that number was calculated (I know digital. RF, ehhhhhhhh.....)

A quarter-wave vertical (what you have here) needs a quarterwave counterpoise. A quarterwave at 1030MHz is about 29m (neglecting velocity issues). So a quarter of that plus a little more fudge for velocity factor.

Quote:

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Originally Posted by FlyingRon

A quarter-wave vertical (what you have here) needs a quarterwave counterpoise. A quarterwave at 1030MHz is about 29m (neglecting velocity issues). So a quarter of that plus a little more fudge for velocity factor.

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Ron, I think you mean a full wavelength at 1030 MHz is about 0.29 meters, so a quarter wavelength counterpoise would be 0.0725 meters, or 2.8543307 (~3) inches.

Yeah, 29 cm or .29m. Careless typing on my part. The answer is the same.

Three inches? Cool.

Why that?

* Glassy eyed stare *

Yeah, three inches. Cool.