A triple-band circularly polarized annular ring antenna with asymmetric ground plane for wireless applications

Herein a compact triple-band circularly polarized (CP) microstrip patch antenna, loaded with a single annular ring patch with eight symmetrical slots along its periphery and a series of octagonal closed ring resonators (CRRs) on the opposite side of the substrate, is proposed. Evolution process of the antenna geometry reveals that the eight symmetrical slots and the CRRs are responsible for increased impedance bandwidth (IBW), while simulated (high-frequency structure simulator (HFSS) and computer simulation tool) triple CP bands obtained due to the uses of crossshaped slit resonating at 7.5GHz (152.2MHz); asymmetric ground plane at 10.2GHz (161MHz); and square open-loop at 12.2GHz (112.5MHz). Series of parasitic strips improved CP radiation and remove ripple in the radiation pattern. The antenna presented here, is compact, fabricated with an optimized dimension of 35x30x1.6mm(3), on low cost FR-4 substrate with copper cladding. The measured <10-dB IBW ranges from 4.08-5.05GHz and 5.98GHz up to 13.6GHz. Simulated maximum peak gain found to be 4.45 dBi at 13GHz. The antenna proposed herein is appropriate for wireless applications.