Wideband Circularly-Polarized Patch Antenna

A novel wideband circularly-polarized patch antenna is presented. First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports. Then, a circular patch antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented. The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid. It is found that the antenna can deliver a measured impedance bandwidth of 79.4% from 1.04 to 2.41 GHz for SWR 3 dBi. The simulated impedance bandwidth is 94% from 0.9 to 2.5 GHz for SWR 3 dBi. Good agreement is observed between simulation and measurement

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