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, the CP design for the stand-alone slotted patch antenna is investigated, and a 3dB-axial-ratio bandwidth of 53 % is obtained. Then, the metallic reflector is placed at the rear of the slotted patch to generate unidirectional radiation. Experimental results demonstrate that the slotted patch antenna with a reflector has almost the same CP bandwidth as the stand-alone slotted patch antenna, and it has good impedance matching as well as stable radiation patterns across the CP operating frequencies.