Gain enhancement microstrip antenna with slots loaded in the ground plane

The article presents a novel circular polarization (CP) design of a single-feed equilateral-triangular microstrip antenna to achieve enhanced antenna gain. This technique is obtained by placing three triangular slots at locations below the equilateral-triangular radiating patch in the ground plane. By adjusting one of the triangular slot's side lengths to be slightly longer than that of the others, two orthogonal near-degenerate resonant modes for CP radiation can be excited. The measured antenna gain in this study can be easily increased by 3.3 dBi as compared to the same height, operating frequency and radiating patch shape of a regular equilateral-triangular microstrip antenna without triangular slots in the ground plane. A prototype antenna is fabricated for experimental evaluation. Simulated and measured results are presented.