Compact Wideband Circularly Polarized Patch Antenna for CNSS Applications

A compact wideband circularly polarized (CP) patch antenna utilizing a quad-feed network (QFN) and quadruple semi-fan-annulus (QSFA) patches is proposed. For using a coupled-line dual-band power divider (PD) and improved phase shifter (PS) with stepped-impedance-open-stub (SIOS), the QFN has a compact size and exhibits the electromagnetic (EM) simulated bandwidth over 96% for the power distribution -6.5±0.5 dB, return loss (RL) > 14 dB, and a consistent 90° (±9°) phase deviation. Moreover, the QSFA patches can expand the CP bandwidth and reduce the size of the antenna effectively. Measurement results show that the proposed antenna achieves CP bandwidth of 72% from 1.15 to 2.45 GHz for RL > 10 dB, axial ratio dB, and 3-dB gain variation (gain > 4.4 dBi). Therefore, the proposed antenna is a good candidate for Compass Navigation Satellite System (CNSS) applications.