Wideband Circularly Polarized Slotted-Patch Antenna With a Reflector

A design for wideband circularly polarized (CP) antennas with unidirectional radiation is described. The antenna structure is mainly composed of a rectangular slotted patch and a metallic reflector. First, an optimum CP design for the standalone slotted patch antenna is investigated, and a 3-dB-axial-ratio bandwidth of 53% is obtained. Then, the metallic reflector is placed at the rear of the slotted patch for generating unidirectional radiation, and the effects of various reflector sizes on CP performances are studied. Measured results show that the slotted patch antenna with a reflector has almost the same CP bandwidth as the standalone slotted patch antenna, and it has good impedance matching as well as stable radiation patterns across the CP operating frequencies.