X-band metamaterial-based Luneburg lens antenna

A metamaterial-based low profile antenna is presented in the 8-12 GHz frequency range (X-band). The antenna is designed in a parallel-plate TEM waveguide configuration. A planar metamaterial-based Luneburg lens and a Vivaldi antenna that illuminates the latter lens are embedded inside the TEM waveguide. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary non-resonant metamaterial structures. Numerical simulations are performed to determine the suitable unit cells geometry with respect to the wave launcher. A prototype has been fabricated using standard printed circuit board techniques and has been measured in an anechoic chamber. A good qualitative agreement is observed between simulations and experiments. The proposed planar antenna presents good focusing properties over the X-band frequency range.