Compact design of single-feed circularly polarised microstrip antenna

A compact design of a single-feed circularly polarised (CP) microstrip antenna with relaxed manufacturing tolerances is presented. The CP operation of the microstrip antenna is achieved using a cross slot embedded on the radiating patch. By cutting an additional cross slot on the ground plane, not only the CP operating frequency can be decreased but also the slotlength ratio of the cross slot on the radiating patch can be considerably increased. In addition, the performance of the proposed design, such as CP bandwidth and peak gain, have no significant reduction.