Low RCS circularly polarized antenna design using a polarization conversion metasurface for satellite and navigation

Achieving low radar cross section (RCS) and circular polarization (CP) is crucial for antenna designs in satellite and navigation applications. Conventional approaches often involve additional metasurface (MS) layers, modifications to the radiating patch, or separate feeding networks, which increase structural complexity, reduce aperture efficiency, and compromise radiation performance. This paper proposes a novel design for a low RCS circularly polarized antenna (CPA) using a polarization conversion metasurface (PCM) that integrates both RCS reduction and CP generation within a single compact structure. The proposed multifunctional MS serves as both a linear polarization converter and a CPA. This integration minimizes structural complexity while ensuring high radiation efficiency and effective RCS reduction. A novel feeding network is incorporated into the MS to precisely control the phase difference between orthogonal excitations. Dual input feeds are positioned along the x- and y-axes to generate the transverse magnetic (TM₀₁₀) and TM₀₀₁ modes, respectively. A controlled 90° time-phase difference is achieved by applying phase ϕ to the x-axis feed and ϕ + 90° to the y-axis feed. This precise phase alignment ensures optimal CP generation while maintaining a compact and structurally efficient design. The antenna operates with a CP bandwidth of 5.52-5.78 GHz and a peak boresight gain of 13.5 dBi. The proposed antenna design is verified through both simulation and experimental measurements, showing significant improvements in CP performance, RCS reduction, and radiation efficiency. These results confirm that the antenna is highly suitable for next-generation satellite and navigation systems.