Lensters — The evolution from filter to lens and beyond

A prototype gradient index lens has recently been produced by using a stack of frequency selective surfaces, based on a square patch unit cell. The lens was modelled using a transmission line method(TLM) and HFSS. Additional measurements have been taken using a VNA which allows for detailed magnitude and phase information at precise frequencies. The lens has a broadband performance due to non resonating metamaterial structure used. A proposed solution is given to increase the performance of the GRIN lens by the use of antireflection coating built into the design of the lens.