Pin‐loaded circularly‐polarised patch antenna with sharpened gain roll‐off rate and widened 3‐dB axial ratio beamwidth

A circularly‐polarised patch antenna with the loading of shorting pins is proposed in this study to sharpen the gain roll‐off shape and widen the 3‐dB axial ratio beamwidth (ARBW). First of all, it is theoretically revealed that when the electrical size of a circular patch radiator is appropriately constituted, the radiation gain at the horizon can be significantly suppressed and the axial ratio can be maintained below 3 dB over a wide angular range. By introducing a set of metallic pins, which short the patch in a circular contour, the resonant frequency of the antenna will be increased. In this way, the patch radius with respect to wavelength can be freely chosen, so that sharp gain roll‐off rate and wide ARBW can be simultaneously achieved. After the extensive analysis is executed, two circular patch antennas with and without loading of shorting pins are designed, fabricated and tested for comparison. Simulated and measured results show that the gain roll‐off is enhanced up to near 20 dB and 3‐dB ARBW is extended to around 140° so as to effectively reduce the undesired multipath interference as highly demanded in the application of global navigation satellite system.