Integrated single-fed circularly-polarized patch antennas with high-Q cavity filters

A circularly-polarized (CP) filter/antenna system is presented herein. The filter/antenna system is formed by a cavity resonator and a single-fed corner-truncated patch antenna. The corner-truncated patch works as both a resonator of the cavity filter and a CP radiating element. By vertically integrating the CP patch antenna with the cavity resonator, a second-order filtering response is obtained with near-zero transition loss and a reduced size. The filter/antenna operates at the center frequency of 10.08 GHz with a fractional bandwidth of 11% and an axial ratio bandwidth of 1.5%. The gain of the CP filter/antenna is 7.35 dBi. The overall efficiency of the integrated filter/antenna is approximately 96%.