Average Transition Conditions for Electromagnetic Fields at a Metascreen of Vanishing Thickness

Using a dipole interaction model, we derive generalized sheet transition conditions (GSTCs) for electromagnetic fields at the surface of a metascreen consisting of an array of arbitrarily shaped apertures in a perfectly conducting screen of zero thickness. Use of the GSTCs permits modeling of structures containing perforated surfaces much more rapidly than is possible with full-wave numerical simulations. These conditions require that the period of the array be smaller than about a third of a wavelength in the surrounding media, and generalize many results previously presented in the literature. They are validated by comparison with results of finite-element modeling, and show excellent agreement when conditions of their derivation are satisfied.