A CPW-fed non-uniform metasurface antenna with low-profile and wideband circular polarization property

This paper proposes a low-profile, coplanar waveguide (CPW)-fed non-uniform metasurface (MS)-based antenna with wideband circular polarization (CP) and compact geometry. The design integrates rotationally asymmetric slots in the CPW ground plane and spatially truncated non-uniform MS elements on a single-layer Rogers 5880 substrate (55 × 55 × 3.5 mm3). Through systematic characteristic mode analysis (CMA), orthogonal degenerate modes are excited by structural asymmetry, achieving balanced amplitude and a 90° phase difference. Simulations reveal a −10 dB impedance bandwidth of 5.2–6.8 GHz (24.6% fractional bandwidth) and a 3 dB axial ratio (AR) bandwidth of 5.2–5.96 GHz. Experimental validation demonstrates a measured impedance bandwidth of 5.2–6.8 GHz and an AR bandwidth of 5.2–5.92 GHz, alongside a peak gain of 6.9 dBic, cross-polarization suppression below −30 dB, and stable broadside radiation patterns. The truncated outer MS elements suppress higher-order modes, enabling a low-profile configuration (0.04λ0 at 5.5 GHz) while outperforming prior works in bandwidth and polarization purity. This work establishes a CMA-driven framework for merging structural asymmetry with modal orthogonality, offering a robust solution for satellite communications and 5G systems requiring wideband CP radiation.