A Compact High-Gain Circularly Polarized Microstrip Antenna With Enhanced Bandwidth

In this letter, a low-profile, compact, circularly polarized (CP) microstrip patch antenna with enhanced axial-ratio bandwidth (ARBW) and high gain is proposed. Unlike conventional dual-orthogonal feeding schemes that excite two orthogonal modes from two neighboring square patch edges, the proposed feeding scheme simultaneously excites two orthogonal modes with inherent 90° phase difference along a single edge, without external power dividers or phase shifters, yielding two AR minima. Based on this novel CP generation mechanism that applicable to dual-mode resonators with a pair of degenerate modes, a high-gain CP microstrip antenna with pin-loaded patch radiator is presented. Experimental results demonstrate that high realized gain of 10.3 dBic is obtained under a compact transverse radiator size of 0.23λ0 2. In particular, benefitting from the concise single-feed configuration, high overall efficiency up to 95% is accomplished. With broad ARBW (4.1%), high gain (10.3 dBic) electrical characteristics and low profile (0.03λ0), compactness structural properties, the developed design scheme serves as a good candidate for space-constrained wireless platforms