Genetic algorithm optimisation of pyramidal absorbers loaded with a binary FSS

This paper describes a new type of pyramidal absorber design for use in anechoic chambers. To improve the absorbers performance at low frequency, it is loaded with impedance in the form of a frequency selective surface (FSS). A technique for optimising the pattern, and therefore impedance, of the FSS is explained. Finally, the reflectivity response of the new design is simulated and compared against those of an unmodified pyramidal absorber and one loaded with a single square loop FSS.