Wideband circularly polarized SIW cavity-backed patches antenna for wide-angle scanning phased arrays

A single-feed wideband circularly polarized (CP) substrate-integrated waveguide (SIW) cavity-backed antenna and its phased array are presented in this paper. The proposed element consists of SIW cavity, stacked patches, and a 50-Omega coaxial probe. The coaxial pin is directly connected to the two patch radiators. By chamfering on each rectangular patch, the proposed SIW cavity-backed patch antenna realizes wideband circular polarization characteristic. The proposed element exhibits a simulated impedance bandwidth of 22.5% (14-17.6 GHz) for |S-11| < -10 dB, an axial-ratio (AR) bandwidth of 12.9% (14.5-16.5 GHz) for AR <= 3 dB. Simulation results illustrate that the infinite array can scanning up to +/- 60 degrees in all planes over the operating frequency, under the criterion of active VSWR <= 3 and AR <= 3 dB. For verification purpose, an 8 x 8 array prototype was manufactured and measured. To achieve better CP characteristics, the sequential rotation technique is applied to the full array configuration. The measured results show good agreement with simulation results.