A multi-beam circularly polarised Fabry-Perot resonator antenna array using SIW for X-Band applications

This paper presents a novel multi-layer beamforming antenna array based on Fabry-Perot resonator that is excited by a high-performance compact 4 x 4 Butler matrix using substrate integrated waveguide (SIW) technology for X-band application. The adapted ring patch antenna is fed through the aperture on a rectangular SIW cavity and forms the radiating element in the antenna array. Enhanced characteristics of the antenna array are realised by inserting an electromagnetic bandgap (EBG) structure between the radiating elements and a superstrate constituted from two complementary frequency selective surfaces (FSS) that forms a Fabry-Perot resonator (FPR). Circular polarisation in the proposed FPR SIW antenna array (FPRSAA) is achieved by using a combination of sequential phase rotation and orthogonal feeding techniques. Measured results of antenna array (Ant. II) show |S11| <= -10 dB between 8-12.0 GHz, a circular polarisation (CP) gain variation between 15.64-18.54 dBic, 3 dB axial-ratio between 8.5-11 GHz, and scanning angle covering -47 to 47 degrees.