A shorting post loaded symmetric non-uniform metasurface antenna for broadband circular polarization

Abstract

This paper proposes a symmetric 3 × 4 non-uniform metasurface-based patch antenna to achieve broadband circular polarization. The metasurface consists of rectangular meta-elements symmetrically placed along the vertical axis. To increase the impedance and 3 dB axial ratio bandwidth (ARBW), a shorting post is used in the antenna. The design analysis of the antenna uses the characteristic mode analysis (CMA) of CST MWS. The antenna achieves 39.7% (5.81–8.69 GHz) impedance bandwidth, 33% (5.34–7.45 GHz) 3 dB ARBW, and a peak gain of 7.43 dBi. It is a low-profile antenna with a size of 34 × 34 × 3.04 mm${}^3$ (0.73$\lambda$ $\times 0.73\lambda$ $\times 0.06\lambda$, where $\lambda$ is free space wavelength with an operational frequency of 6.4 GHz). A prototype is fabricated on an I-Tera MT40 substrate. The experimental results agree well with the measured results.