Circularly-polarised slot array with high front-to-back ratio and low axial ratio

A novel design for circularly-polarised (CP) arrays is proposed. The proposed array is composed of dual CP slot antenna elements arranged in a face-to-face configuration, and they are simultaneously excited through a slot line. By properly controlling the excitation amplitudes and phases of the two radiating elements, the cross polarisation and back radiation of the array can be effectively reduced. From the measured results, the proposed array can give an axial ratio of lower than 1 dB and a front-to-back ratio of higher than 12 dB within a 10 dB-return-loss bandwidth of >16%. Simulation results obtained with high frequency structure simu-lator (HFSS) also agree well with the experimental data. © The Institution of Engineering and Technology 2017.