Abstract
The performance of a low-pass screen designed to block electromagnetic waves in a stop band is shown to have an upper bound defined by the static electric and magnetic polarizability per unit area of the screen. The bound is easy to calculate for all angles of incidence and polarizations, and applies regardless of how complicated the screen's microstructure is. For a homogeneous dielectric sheet the bound for TM polarization is more restrictive than the bound for TE, but this is not generally true for a screen with microstructure. The results are verified by measurements and simulations of oblique transmission through an array of split ring resonators, printed on a dielectric substrate.