A coplanar waveguide-fed circularly polarized square slot antenna with the feasibility of obtaining a wider bandwidth and a relatively smaller size is proposed and demonstrated. The proposed antenna, consisting of a stepped feeding strip, a modified grounded L-shaped radiating patch, an inverted-L grounded strip and an asymmetric ground with an L-shaped slot as well as two horizontal slots, is designed, analyzed and fabricated. Good agreement between simulated and measured results is observed. Simulation and measurement results reveal that the proposed antenna can provide an impedance bandwidth of 106.3% (2.3-7.52 GHz) and a 3-dB axial ratio (AR) bandwidth of 90.2% (2.25-5.95 GHz). Additionally, within the effective circular polarization (CP) bandwidth of 88.5% (2.3-5.95 GHz), the proposed antenna has gains from 1.9 dBic to 5.2 dBic with an average gain of 3.9 dBic.
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