A novel flat lens horn antenna designed based on zero refraction principle of metamaterials

In this paper, a horn antenna filled with a metamaterial structure as lens inner the aperture is presented. Unlike conventional curve lenses, the lens is designed in the present work using a fully flat structure, which results in a great improvement for the directivity of the horn antenna based on the zero refraction characteristics of the metamaterial. In this structure, a periodic-structure metamaterial with three-layer metal grids is designed using the CST Microwave Studio for optimization and its zero refraction property is validated. For the characterization of the antenna, the electric-field distribution in radiation area, reflection parameter (S-11), gain and radiation pattern are calculated. The results show that the gain of a wide flare angle horn antenna is enhanced with over 2 dB between 16.10-17.30 GHz after the metamaterial is utilized. Therefore, the metamaterial lens horn structure results in a miniaturized antenna design approach compared to the optimum conventional horn of the same aperture size and gain in the interested frequency band.