Novel design concept of gain enhancement circularly polarized microstrip antennas

A novel circular polarization (CP) design of single-feed microstrip antennas with enhanced antenna gain is presented. This CP design is obtained by placing slots at proper locations below the radiating patch in the ground plane. By adjusting one of the slot's side or protrudent lengths slightly longer than that of the others, two orthogonal near-degenerate resonant modes for CP radiation can be excited. Measured antenna gain in this study can easily be increased by three times, as compared to the same height, substrate material, operating frequency and radiating patch shape microstrip antenna without slots in the ground plane, respectively. Prototype antennas are fabricated for experimental evaluation. Simulated and measured results are presented here.