Design of circularly polarized square microstrip patch antenna

A simple design for a circularly polarized single-feed microstrip square patch antenna is presented. The design method consists of incorporating a narrow slot at the center of microstrip patch, producing a triangle over the slot and placing a single feed along the diagonal of the square patch. By adjusting the dimensions of the narrow slot and triangle, a circularly polarized wave can be generated. The bandwidth of the microstrip antenna can be changed by varying the angle of the triangle produced over the slot. The measured results are in good agreement with the numerical results.