Broadband circularly polarized aperture-coupled microstrip antenna with dual-offset feedlines

A new feeding technique for a broadband circularly polarized aperture-coupled patch antenna is proposed operating at X-band. The stacked microstrip antennas are used for broad bandwidth and flat gain. These broadband antennas fed by slot-coupled quadrature hybrid have dual-offset feedlines for low cross-polarization level. The quadrature hybrid has multi-section with multi-layers. The grounds of coupler and antenna are connected by via. The simulated 10 dB return loss bandwidth is 35.5% from 8.1 to 11.6 GHz and the 3 dB axial ratio (AR) bandwidth is 35%.