Ultra‐Broadband and High‐Gain Microstrip Circularly Polarized Antenna with Reflective Quasi‐Achromatic‐Focused Metasurface

ABSTRACT In this paper, an ultra‐broadband circularly polarized (CP) antenna equipped with quasi‐achromatic‐focused metasurface (MS) is proposed. To enhance the C‐shaped CP antenna's radiation performance, we designed a MS‐based on Pancharatnam‐Berry (PB) phase theory. Positioning the initial C‐shaped CP antenna at the focal point of the designed quasi‐achromatic‐focused MS enabled an antenna loaded with MS achieving CP radiation. This MS antenna system demonstrated a peak gain of 13.77 dBic with an average gain exceeding 10 dBic over the 4.52–12.82 GHz band (relative bandwidth: 95.7%). Concurrently, its 3‐dB axial ratio bandwidth reached 89.1%, covering 4.6–12 GHz. This work provides an efficient method to enhance antenna gain in wideband wireless communication systems.