Genetic Algorithm optimisation of dual polarised pyramidal absorbers loaded with a binary FSS

This paper describes a new type of pyramidal absorber for use in anechoic chambers. To improve the low frequency performance of the absorber, it is loaded with impedance in the form of a frequency selective surface (FSS). A technique for optimising both the pattern and the position of the FSS is discussed which maximises the absorber's bandwidth for use with either TE or TM incident waves.