Broadband Single-Feed Metasurface-Based Circularly Polarized Antennas

This paper studies metasurfaces for low-profile single-feed circularly polarized (CP) antenna design with broadband performance. The antenna comprises a metasurface, a rectangular patch (RP) radiator, and a coaxial probe. A comparative analysis of the antenna's performance over five different metasurface configurations is presented and discussed. Key design parameters including the aspect ratios of the RP radiator as well as a metasurface unit cell, the number of unit cells, and the feed location along the diagonal line, are crucial for optimizing the broadband CP performance. The antenna prototype, utilizing a metasurface with 7×7 rectangular-patch-unit cells, achieves a bandwidth of 22.2 % (3.6 GHz-4.5 GHz) for axial ratio <3dB, gain > 6.0dBic, and VSWR≤2.0 with an overall antenna dimension of 80.0mm × 60.0mm × 4.8mm (1.08λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>× 0.81λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>× 0.065λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> at 4.05 GHz).