Compact Differentially Fed Inverted Microstrip Circular Patch With an Integrated Coupler

This letter presents a compact design of an inverted microstrip circular patch differentially fed by an integrated coupler. The compact design offers symmetric copolarized radiation in both principal planes and low cross-polarized radiation in the H-plane. A relatively high gain of 8.3 dBi is experimentally demonstrated. Moreover, the integrated unilayer coupler feed shares a common ground plane with the inverted patch providing a compact design.