Analysis of low-pass filters consisting of multiple stacked FSS's of different periodicities with applications in the submillimeter radioastronomy

A spectral domain approach is presented which allows multiple stacked frequency selective screens (FSS's) to be investigated. The analysis is exact if all arrays have the same periodicity or if a unit cell of finite extent valid for the whole FSS can be defined. Further, this approach can be used as a very efficient approximation for analyzing low-pass filters applied in radioastronomy and consisting of arrays with different periodicities, as long as the unit cell dimensions and the separation between the arrays are small small compared to the wavelength at the operating frequency. Numerical results for several FSS configurations are presented and compared with measured values.