Circularly polarized ring-slotted-microstrip antenna

A compact square-ring-slotted-microstrip antenna is proposed for circularly polarized (CP) radiation and global navigation satellite systems (GNSS). Four square-ring-shaped slots along the diagonal directions are cut symmetrically onto a square patch radiator for CP radiation and miniaturization. The operating frequency can be tuned by varying the ring width. The measured 3-dB axial-ratio (AR) bandwidth of around 25.0 MHz (1.56-1.585 GHz) and 10-dB return loss bandwidth of 80.0 MHz (1.545-1.625 GHz) are achieved.