On Thursday, May 10, 2018 at 9:44:28 AM UTC-7, Darryl Ramm wrote:
On Thursday, May 10, 2018 at 8:08:48 AM UTC-7, Matt Herron Jr. wrote:
On Thursday, May 10, 2018 at 7:38:17 AM UTC-7, wrote:
On Thursday, May 10, 2018 at 10:07:15 AM UTC-4, Matt Herron Jr. wrote:
Flarm antennas are a real pain for ships with carbon hulls. Coverage is always poor, especially below. Is there a way to make a perfectly flat and thin antenna that could be taped to the outside of the hull and fed through a small (1/8"?) hole? I am thinking 2 thin wire strands, or foil strips, fed through from the inside, then taped in place with wing tape. I would put one on either side of the nose for good coverage. The wires could even be longer (some wavelength ratio) for better gain. The tiny hole could easily be filled later if the install was reversed.

Any RF engineers out there care to take a shot at this?

The power radiation pattern would not be favorable.
UH

Why is that?

Laws of physics/Maxwells' equations, antenna design theory, radiation/gain patterns of patch antennas,.... there are lots of articles online about patch antenna design and performance if you want to drill there.

You can't just tape a wire near a conductive surface and think you have built an antenna. That is likely to create a non-antenna. You need a proper designed patch antenna..

Patch antennas attached to glider sides are going to have very limited forward/rear visibility (the directions that matter the most) and I expect you would need more than those two side antennas to provide coverage around the aircraft, and that is all non trivial to combine. We've got two FLARM receivers in PowerFLARM to do that, and in the USA only one of those also transmits, and only one ADS-B receiver, not close enough to what you would need for 360 coverage.

Patch antennas work great for entirely different things like looking in one basic direction, like "up" for GPS and Globalstar and Iridium, all with circular polarization, which importantly makes them horizontal rotation orientation independent (although patch antennas don't have to be circular polarized).

It's possible to get standard FLARM antennas to work in your ASW27 so just go that route.

Darryl (background in microwave electronics research).

How do I get coverage below the glider in this scenario?