Efficient design of a frequency selective surface for a multi functional radar: theory and measurements

This paper describes an efficient methodology for the design of steep roll-off Frequency Selective Surfaces (FSS??s). The proposed technique is based on the Multimode Equivalent Network (MEN) approach, which was originally developed for the analysis of waveguide junctions. The MEN has been extended to the study of multi-layer patch based and aperture based FSS??s. The result is a general formulation that allows characterizing complex structures, consisting of radiating apertures and FSS??s, in the same framework used to account for feeding and filtering elements inside the waveguides. Moreover, thanks to the modularity of this approach, it will he shown in the paper that it can he used as agile design tool. In particular, this paper describes the design procedure for a multi-layer FSS to he integrated with the X-hand phased array of a Multi Functional Radar (MFR) in order to prevent interference from an antenna located in its proximity and operating in a partially overlapping frequency range. The analysis results of this integrated structure, obtained with our tools, were compared with those produced by a commercial code, showing very good agreements. The designed FSS has been manufactured and measured for different incidence angles.