A versatile technique is described for obtaining the full-wave characteristics of structures composed of conductors and dielectrics. It involves the replacement of the dielectric regions by an equivalent interlocking array of thin-wall sections, to which are then attributed appropriate surface impedances. Through the use of a two-dimensional rooftop current representation and line-function testing of the electric field, matrix equations appropriate for propagation, radiation, and scattering problems are generated and solved. In this paper, we concentrate on the physical principles, and demonstrate the usefulness of the approach by solving a wide variety of practical problems. © 1992, IEEE. All rights reserved.