Characteristic Modes Analysis of a Near-Field Polarization-Conversion Metasurface for the Design of a Wideband Circularly Polarized X-Band Antenna

A metasurface (MS) based on loop elements operating in the near field of a linearly-polarized microstrip antenna is employed to realize circularly polarized radiated field. The properties unit cell are highlighted with help Characteristic Mode Analysis that for investigating achievable linear circular polarization conversion bandwidth and providing guidelines design final antenna. finite structure comprising 4×4 cells tailored achieving far within whole X-band adopted satellite communications (7.25 GHz-7.75 GHz, 7.9 GHz-8.4 GHz). simple but effective single-port excitation scheme adopted, overall performance assessed by measurements fabricated prototype. good agreement between simulated measured results confirms reliability proposed approach as well meaningful insight provided Modes Theory.