Broadband circularly polarised proximity coupled patch antenna

Abstract

We demonstrate that a square patch fed simultaneously on all four sides by a new type of printed broadband proximity feed excited by a wide band balun achieves: for linear polarisation an impedance bandwidth of more than an octave band (0.82 to 2.42 GHz); and for circular polarisation, a 3 dB axial ratio bandwidth of 30% and excellent pattern stability over a 50% bandwidth. Another novel feature of the 1 GHz circularly polarised antenna presented is that, the dimensions of the patch are reduced by 60%, compared to the conventional patch dimensions required for the same frequency of operation.