Pin-Loaded Circularly-Polarized Patch Antennas With Wide 3-dB Axial Ratio Beamwidth

Abstract

Pin-loaded circularly polarized (CP) patch antennas with wide 3-dB axial ratio beamwidth (ARBW) are proposed in this paper. The ARBW of a CP patch antenna is mainly dependent on its electrical width at a frequency, while the patch size at resonance is fully controlled by the shunt inductive load. First of all, four shorting pins are introduced along the diagonals of the dual-fed square patch, so as to exhibit that the 3-dB ARBW can be significantly extended if the shorting position and pin radius are properly chosen. Next, the two degenerate modes in a single-fed CP patch antenna are slightly separated in resonant frequencies by loading another pair of shorting pins along the central line of the patch, so as to excite CP radiation. After extensive analysis is executed, two patch antennas with and without shorting pins are fabricated and measured. Simulated and measured results show good agreement, and both of them demonstrate that the 3-dB ARBW is tremendously improved from 50° to 140° or gets nearly 90° increment by means of the proposed method.