Probe-fed compact circular microstrip antenna for circular polarization

A novel design of a probe-fed circular microstrip antenna with a group of four slits inserted at the circular patch boundary for achieving compact circular polarization (CP) operation is presented. The proposed design can make its excited fundamental-mode patch surface current path much longer than that in a conventional circular microstrip antenna with the same antenna size, which makes the present proposed design have a reduced antenna size at a given operating frequency. By further incorporating a pair of peripheral cuts in the circular patch, compact CP operation can easily be obtained using a probe feed. Results have been obtained showing that, for a given operating frequency, the antenna size reduction of the proposed design can be as large as 50%, as compared to the regular-size circularly polarized circular microstrip antenna. Details of the proposed antenna designs are described, and experimental results of the obtained CP performance are presented and discussed. (C) 2001 John Wiley & Sons, Inc.