Z-Shaped Slot-Excited Hybrid Polarization-Rotated Metasurface Antenna for a Wideband Quad Circularly-Polarized-Mode Radiation Using CMA

In this work, a novel hybrid polarization-rotated metasurface (PRMS) structure is firstly proposed and excited by a Z-shaped circularly-polarized (CP) coupling slot to obtain a wideband quad CP-mode radiation. In detail, the hybrid PRMS structure comprising two types of corner-truncated unit cells, as a radiator, is employed to generate three distinct CP modes. Through rigorous optimization, the Z-shaped CP slot simultaneously excites these three CP modes while producing an extra fourth independent CP mode. By using characteristic mode analysis (CMA), these four CP modes can be combined for a wideband broadside radiation. Measured results demonstrate a large impedance bandwidth of 40.3% (6.07∼9.13 GHz) and a 3-dB axial ratio bandwidth of 41.1% (5.81∼8.83 GHz). Additionally, a peak gain of 9.52 dBic and a wide 2-dB gain variation bandwidth of 30.1% (6.21∼8.41 GHz) are achieved.