A Compact Circularly Polarized Patch Antenna with Ring Reflector

A miniaturized antenna with circular polarization and directional pattern is presented in this paper. The conventional ground plane is replaced by a rectangular ring reflector to form the directional pattern. Since the side length of the ring reflector is around quarter-wavelength, the total size of the proposed antenna is reduced dramatically, which is about lambda(g)/2 x lambda(g)/2 in the horizontal plane. In addition, the performance of the proposed antenna is still comparable with the convetional microstrip antenna. The simulated gain is 6.1 dB at the 1.575 GHz, while the back radiation is only -11.6 dB. To verify the proposed design, a protype is fabricated and measured. Good agreement is observed between the measured and simulated results.