Fundamental constraints on the electrical characteristics of frequency selective surfaces

This paper presents analytical constraints for the values which the reflection coefficient of any Frequency Selective Surface (FSS) can assume, This includes both patch and slot type FSS. The main assumption in this paper is that the FSS is a planar periodic surface constructed of infinitesimally thin conductors with a finite number of dielectric substrates and superstrates. In addition, only one periodic screen can be present, and it must be infinite in extent. Other than infinitesimal thickness, no assumptions are made on the shape of the periodic scatterer. The analysis presented in this paper includes the effects of dielectric layers, angle of incidence, and polarization. The results of the analytical constraints is the development of charts which can help one better understand fundamental FSS behavior. This includes a fundamental limit on how much power a lossy FSS can dissipate, This fundamental limit also applies to the amount of power that can be redistributed to grating lobes.