Broadband circularly polarized aperture-coupled microstrip antenna mounted in a 2.45 GHz wireless communication system

A novel dual-feeding technique for a broadband circularly polarized aperture-coupled microstrip antenna operating in a 2.45 GHz system is presented. The dual feeds are placed in orthogonal directions, and are connected to a Wilkinson power divider with a 90° phase shift between its two output feedlines. Proper positioning of the coupling slots results in high port solution (>40 dB), and a purity of circular polarization is obtained. A broad impedance bandwidth (VSWR≤2) of about 54.7% and a 1 dB axial-ratio bandwidth of about 9.8% were achieved.