Fabry-Perot approach to the design of double layer FSS

The analysis of the Fabry-Perot interferometer (FPI) is extended to cascaded surfaces with frequency dependent reflectivities, and provides a systematic procedure for the design of multilayer frequency selective structures (FSS). The FPI concept is also useful in diagnosing the origins of features in the transmission/frequency response curves. The approach eliminates much of the uncertainty in the initial design stages, where placing transmission and reflection bands at required frequency locations demands time and computing resources. The paper concentrates on double layer FSS and the application of the technique for design and diagnosis is illustrated by reference to the design of dichroic structures for microwave and submillimetre wavebands.