S_Dave

Bill,

Thanks for posting that link to the G.P. patch. It's very informative and I hadn't seen it yet.

I had a project years ago, to develop a patch antenna that would have 10% bandwidth. There was some literature on the patch, and the folks who make Ball jars for canning had an aerospace division that had done a lot with patch development for missiles and aircraft. They had a good design section in the "Antenna Engineering Handbook" by Johnson and Jasik. I made dozens of patch antennas and swept them on the network analyzer to test their match and performance.

That article that you mentioned is correct, in that a patch can be fairly simple. Some are made of circuit board with copper on both sides--they etch the patch on the front; the back stays copper for the ground plane. Feed point is some distance in from the edge, with high Z at the edge, and lower as you go in--nominally 50 ohms to match coax. The material that's in between the copper determines the bandwidth--how far off perfect freq. it will still perform--with vacuum or air being the best. Thus, his spacer blocks are establishing air as the dielectric, and giving the most bandwidth. More bandwidth also means you can be off the perfect dimensions and it may still work fine, being still inside the tolerance.

Ground plane size isn't critical, but more is better.

Here's something that I don't think has been mentioned--polarization sense. You must have your receiving and transmitting antennas oriented the same--vertical or horizontal, etc. or both CP with the right sense. For a vertical whip antenna, your patch should be turned to be vertical, too. This will mean that the short distance between feedpoint and edge is up and down, not side to side.

Hey, JP,
Thanks for the thumbs up on Range Video. I'll be ordering from them soon.

Good flying weather here in Georgia. Hope you guys are enjoying the same.
Cheers,

Dave