A Circularly Polarized Annular-ring Patch Antenna with a Groundplane EBG Annular-slot Array

The effects of tuning the parameters of an annular-ring circular patch antenna with a cross-slot are analyzed and discussed. Then, based on this structure, a novel antenna with an electromagnetic bandgap cell system, which consists of a 4×4 annular-slot array in the groundplane, is designed and both numerically and experimentally evaluated. When compared to the annular-ring patch antenna on a groundplane of the same size without EBG structure, the proposed antenna presents a significant increase in the impedance bandwidth, axial-ratio bandwidth and gain. On the other hand, the insertion of the EBG structure allows a 10% reduction of the centre frequency when compared to the annular-ring patch antenna on a conventional groundplane.