A novel wideband compact circularly-polarized metasurface antenna for modern vehicular communication systems

In this work, a wideband compact circularly polarized (CP) antenna using a novel polarization-rotated metasurface (MS) structure is presented. First, the polarization-rotated MS structure is designed by using a complementary L-shaped MS unit cell. By optimizing the width of diagonal gap and radius of corners, the amplitude and phase of its surface impedances along ±45° can be adjusted respectively, and then a large polarization-rotated bandwidth of 44.4% can be obtained. Secondly, the modal behaviors of the proposed MS are also investigated by adopting characteristic mode analysis (CMA) to explore feasible CP radiation. Furtherly, the proposed MS is applied to construct a wideband CP MS-based antenna by combining with a coupling slot. The experimental results show a large 3-dB axial ratio (AR) bandwidth (~31.1%), a large 10-dB impedance bandwidth (~41.8%) and a compact size of 0.63λ0 × 0.63λ0 × 0.08λ0, verifying that the proposed antenna can be applied to realize a high-quality vehicular communication.