Metasurface-loaded printed monopole antenna: tailoring impedance for wideband radiation

Abstract

Abstract In this paper, we propose a method of designing a wideband printed monopole antenna (PMA) by loading metasurface on its back. The metasurface-loaded PMA prototype is a double-sided structure, with the printed monopole on the front side and the metasurface etched on the back side, respectively. Driven by the printed monopole structure in the near-field zone, the metasurface can behave inductively or capacitively. By adjusting the geometrical parameters, the impedance of the metasurface can be tailored so as to compensate the mismatched impedance of the original printed monopole in a wide band, leading to a wideband omnidirectional radiation. To verify this method, a light-weight PMA is designed, fabricated and measured. Analyses of the impedance and the surface current distributions are employed in the design process. The height of the proposed PMA is 20.0 mm, about 16% of the wavelength corresponding to the lowest operating frequency. Both the simulated and measured results show that the antenna can achieve highly efficient omnidirectional radiation in 2.50–4.75 GHz and the relative bandwidth achieves up to 62%. This work provides an effective alternative of designing wideband PMA, and may find wide applications in modern wireless communications.