Design of Broadband Circularly Polarized Patch Antenna Based on Multi-feed Method

A novel broadband circularly polarized patch antenna based on the multi-feed method has been proposed in the article. Four signals with identical amplitude and 0°, 90°, 180° and 270° phase shift are produced by the feeding network which includes power dividers with different transmission length. Through the quadruple feeding probes, the microstrip patch above the air layer is excited by these signals and circularly polarized electromagnetic waves can be radiated. In order to broaden the bandwidth of the circularly polarized patch antenna, the power coupling is performed by using F-probes. The Simulation results show that the antenna achieves 83.6% impedance bandwidth ( VSWR ≤ 2) and 61.8% axial ratio bandwidth ( AR ≤ 3dB). Compared with the dual F-probes or quadruple L-probes excitation mechanisms, the quadruple F-probes feeding mode has a significant effect in broadening the impedance bandwidth and the axial ratio bandwidth.