Miniaturized Wideband Metasurface Antennas

The single- and dual-layer metasurfaces are proposed to miniaturize a low-profile wideband antenna. The single- and dual-layer metasurfaces consist of one and two square patch arrays, respectively, both supported by grounded dielectric substrate to form the waveguided metamaterials. After retrieving the effective refractive index along the propagation direction in the waveguided metamaterial, the effective propagation constant is subsequently derived to initially estimate the resonant frequencies of the dual-mode antenna. With the increased effective refractive index, both the proposed antennas realize the gain greater than 6.5 dBi over the bandwidth of ~30% with a reduced radiating aperture of <inline-formula> <tex-math notation="LaTeX">$0.46\lambda _{0} \times 0.46\lambda _{0}$ </tex-math></inline-formula> and a thickness of <inline-formula> <tex-math notation="LaTeX">$0.06\lambda _{0}$ </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 5.5 GHz). Moreover, the dual-layer metasurface provides more freedom to increase the effective refractive index with achievable gap widths compared with the single-layer metasurface.