A compact wideband and high gain GRIN metamaterial lens antenna system suitable for C, X, Ku band application

Abstract

In this paper, a rectangular split ring resonator (RSRR) based gradient refractive index (GRIN) metamaterial structure arranged in 30 × 10 array of size 4 cm × 4 cm for lens antenna is addressed. The novelty in the design lies in the introduction of the splits in the rectangular rings in order to enhance the coupling of the currents between the rings. This ultimately results in the collimation of the field in the desired direction and improves the gain and bandwidth of the antenna system. The multilayer metamaterial structure is proposed to design a low loss, broadband, highly focusing thin lens. The metamaterial lens array is combined with a horn antenna system to achieve a gain improvement of 3–11 dB and cross polarization level below −23 dB in the frequency range of 3.5–19.5 GHz with a −3 dB gain bandwidth efficiency of 113%. The metamaterial medium parameters such as permittivity(ε), permeability(μ) and refractive index(η) variation of the proposed design is found to reveal its near zero values in the operating range, depicting it as a near zero metamaterial (NZMTM). The variation in the refractive index of the metamaterial lens is due to parasitic coupling between the metamaterial layers and that facilitates to design thin broadband lens antenna system. This broadband high gain lens antenna is found suitable for C, X, Ku band application.