Circularly polarized square slot antenna with a pair of inverted-L grounded strips

This report presents a novel wideband circularly polarized square slot antenna (CPSSA) fed by a coplanar waveguide (CPW) for broad bandwidth and circular polarization performance. The proposed antenna structure consists of a diagonally placed, tapered radiating feed stub and asymmetrical slot modifications within a compact square ground plane. By incorporating perturbation elements and a non-uniform feed geometry (including a “lightning-shaped” feedline and a pair of inverted-L shaped grounded strips in the slot), the antenna achieves broadside circular polarization (CP) with a wide axial ratio (ARBW) bandwidth. The optimized antenna exhibits an AR bandwidth (AR < 3 dB) exceeding 25%, while the simulated impedance bandwidth (IMBW) (for <–10 dB) is 46%. These results demonstrate a significant improvement over conventional microstrip patch CP antennas, which typically suffer from narrow bandwidth. The antenna’s simple planar construction and broadband CP performance make it a strong candidate for modern wireless communication systems requiring flexible orientation and high data-rate capability.