Elliptical ring patch antenna for circular polarization

The performance of an elliptic ring as a circularly polarized antenna is studied both theoretically and experimentally. The analysis is carried out using the generalized transmission line model (GTLM). It is found from theory that if the major and the minor axes of the confocal ellipses of the ring are selected judicially, a good circularly polarized wave can be achieved over a moderately wider frequency range. The directive gain of an elliptical ring is larger by an amount of 2 to 3 dB, compared to the circular and elliptical patch antennas. An elliptical ring was designed, fabricated, and tested. The radiation patterns of the patch are measured with a uniformly rotating linearly polarized antenna. The experimental pattern shows a very good quality of circularly polarized wave with an axial ratio of less than one dB and an overall gain of about 9.5 dBi.<>