Compact microstrip circular patch antenna for Wi-Max with double-layered substrate

A new circular polarization (CP) design for single-feed microstrip patch antennas is presented and studied. The proposed design is much simpler in construction compared to the traditional wide-band patch antenna. For the desired results, two slots are inserted into the patch antenna. Bandwidths as high as 10% are achieved with stable pattern characteristics, such as gain and cross polarization, within its bandwidth. This design technology is achieved by embedding two narrow slots on the microstrip antenna and placing a single feed along the 45deg axis of the circular patch. By properly adjusting the length of the narrow slots, the circular polarization wave can be easily excited. Typical results of the CP microstrip antennas obtained by applying this design method are presented and discussed.