I am opening this thread for suggestions and help in designing a better circularly polarized patch antenna. Currently all units that I know of are "trimmed corners" patches. These have less than ideal axial ratio and are very critical to their dimensions. Out of spec dimensions result in loss of circularity as well as huge drops in SWR.
Thus I would like some assistance in developing a dual feed patch.
There are two ways to do this:
1. feed a square 50 ohm patch 90 degrees apart and do impedance transformations with 75 Ohm coaxial cable and add a 90 degree 50 ohm phase shifting stub.
This method is easiest to design.
2. Feed a square patch at its 100 Ohm impedance points at different sides and use a 90 degree, 50 ohm phase shifting match.
This is a bit hard to design, but will be easier to build.
I leave this open for discussion. I will provide my research and calculations. If anyone has any helpful input, please post it.