A Cavity-Backed Spiral Slot Antenna with Wide Axial Ratio Beamwidth for GPS System

A monofilar spiral slot antenna with a cavity-backed reflector is presented, which can achieve the performance of the wide axial ratio beamwave for global positioning system (GPS) system. It comprises an arrangement of a single printed spiral slots fed by a 50-Ω microstrip line. By using cavity-backed covering the slot structure, a wide axial ratio beamwidth performance is achieved in the GPS L1 frequency. The angle with less than 3-dB axial ratio at 1.575 GHz in the YoZ plane is about 215°. The measured results show that the HPBW beamwidths at 1.575 GHz are 100° in the YoZ plane, respectively. The peak gain is 5.5 dBic.