Circularly polarized proximity-coupled microstrip antennas

A novel design for the production of circularly polarized radiation (CP) in proximity-fed microstrip antennas is presented. To achieve this circular-polarization design, the two orthogonal modes of the microstrip antenna are excited in series through the proximity coupling of an L-shaped open microstrip line. The experimental results show that the 3-dB axial-ratio CP bandwidth of the proposed design is increased by more than 30%, as compared to a conventional CP microstrip antenna of the same size. The details of the simulated and experimental results for the proposed design are presented and discussed.