Reflectarray design using similarity-shaped fragmented sub-wavelength elements

A new technique for synthesising reflectarray antennas is presented. It uses fragmented elements in a way that allows the elements of the reflectarray to be shape-optimised so that a high degree of geometric similarity exists between adjacent elements. This implies that in the reflectarray each element will see an electromagnetic environment that more closely emulates the infinite periodic environment used to compute the element´s properties. It is shown experimentally that this results in aperture efficiencies closely approaching the upper bounds achievable with a given feed system, and is a significant improvement over that obtained with conventional reflectarrays.