Rigorous and approximate analysis of curved frequency selective surfaces

Curved frequency selective surfaces (FSS) are mostly used for achieving frequency selective sub-reflectors in multifrequency reflector systems, or for making frequency selective radomes. In the first case, curved FSS enables the use of a reflector system for more than one frequency band, i.e. there is a separate feed antenna for each frequency band. In the second case, curved FSS enables mechanical and electromagnetic protection of objects (mostly antennas) inside the radome.