A Wideband, Circularly Polarized, Directive Antenna with a Circular Reflector

Abstract

A two-element, patch antenna with a single feed is presented to achieve wideband, circular polarization, and uni-directional radiation. The driven element of the antenna has a rotated, corner-truncated radiating patch to achieve circularly polarized radiation with an offset microstrip feedline in the front side. The back side of the driven element comprises a wide hexagonal slot, eight meander tips, and a parasitic patch in the center. A circular reflector is added behind the driven element to increase realized gain toward the front side direction of the driven element. A prototype of the antenna is fabricated for validation. In both simulation and measurement, the 3-dB axial ratio bandwidth is fully included in the -10-dB impedance bandwidth. In measurement, the proposed antenna has a -10-dB impedance bandwidth of 83% (1.58 GHz - 3.83 GHz), and a 3-dB axial ratio bandwidth of 49% (1.99 GHz - 3.27 GHz). Within the common band, the average realized gain is 6.1 dBic, and the peak realized gain is 8.6 dBic toward the front side direction of the antenna. The electrical size of the antenna is a kr of 1.69.