A broadband polarization-independent frequency selective surface with an inhomogeneous design

A design flow is presented to design an inhomogeneous frequency selective surface (FSS) whose individual elements consist of hexagon ring elements. With the help of an equivalent circuit, the proportions of the individual hexagon rings are designed in such a way that a polarization-independent high frequency behavior is achieved. Furthermore, different angles of incidence at different locations of the FSS can be considered in the design, as they are typical for divergent radiation fields of feed horns. The presented approach allows the design of inhomogeneous FSS with several thousand design parameters. This allows a concrete application as a frequency selective subreflector (FSSR) in offset parabolic antennas. Measurements have confirmed a very promising performance.