Pac-Man-Shaped Patch-Driven Broadband Circularly Polarized Metasurface Antenna With CMA-Based Quadruple-Mode Excitation

This paper introduces a novel quadruple-mode excited low-profile metasurface (MTS)-based broadband circularly polarized (CP) patch antenna. For a quadruple-mode excitation, the antenna uses a unique pac-man-shaped patch (PSP) as the primary CP radiator and above it a $4\times 4$ sized rectangular MTS, which acts as the secondary radiator. Characteristic mode analysis (CMA)-based mode manipulation approach facilitates effortless separation of two orthogonal modes (OMs) of PSP, creating a 90° phase difference for circular polarization. Further, to increase the design’s axial ratio bandwidth (ARBW), two additional OMs of the MTS layer are cascaded with the PSP modes. Consequently, the four OMs exhibit quadruple-mode excitation, and the design achieves broadband CP radiation. A prototype of the proposed antenna is fabricated using an FR-4 substrate, and the overall dimension of the antenna is $0.55\lambda \times 0.7\lambda \times 0.06\lambda $ at 6.46 GHz center operating frequency. The 10 dB impedance bandwidth of the antenna is 55.22% (4.68–8.25 GHz), and the 3 dB ARBW is 35.48% (5.1–7.3 GHz). It exhibits a peak gain of 6.2 dBi. The measurement results agree well with the simulation results.