A Circularly Polarized Ring-Antenna Fed by a Serially Coupled Square Slot-Ring

An aperture-coupled ring-antenna is presented in this communication. The antenna is fed by a microstrip line through a unique aperture configuration. The aperture contains a square slot ring with four short branch slots protruding toward the center of the ring. It is studied that axial-ratio and return-loss bandwidths of 8.7% centered at 2.53 GHz can be achieved. Within 2.42 GHz-2.64 GHz, the gains are all greater than 7 dBic.