Miniaturized Wideband CP Antenna Using Hybrid Embedded Metasurface Structure

In this study, a hybrid embedded metasurface (MTS) structure is proposed and applied to realize a miniaturized MTS antenna. In contrast to the conventional periodic rectangular MTS, the proposed MTS structure is formed by hybrid embedded patches composed of several X and rectangle metal patches. The gap between the hybrid patches introduces additional capacitances, which can reduce the resonance frequency of the MTS antenna and achieve significant miniaturization. Characteristic mode analysis (CMA) is then utilized to analyze the MTS operating mechanism and guide the best possible feeding positions for wideband circularly polarized (CP) radiation. Subsequently, a cross-slot and microstrip line are used to excite a pair of degenerate modes to obtain CP radiation and broadband impedance matching. Finally, for demonstration, the proposed MTS antenna was fabricated and measured with an overall aperture of 0.46
$\lambda _{0}\times0.46\,\,\lambda _{0} \times0.07\,\,\lambda _{0}$
at 5 GHz. The measured 3 dB axial ratio bandwidth (ARBW) is 21.40%. Thus, it can be demonstrated that the proposed antenna can radiate effectively with significant miniaturization and the desired wideband CP radiation patterns, revealing promising prospects for wireless communication systems.