Diffraction by a Planar Metamaterial Junction With PEC Backing

A uniform asymptotic solution is proposed for solving the local diffraction problem arising from the presence of a discontinuity in planar metamaterial structures. In particular, a junction formed by double-positive/double-negative material layers on a perfect electric conductor ground plane is considered in the case of incident plane waves. The diffracted field is obtained by using a physical optics approximation of the electric and magnetic surface currents in the radiation integral and by performing a uniform asymptotic evaluation of this last. The resulting expression contains the geometrical optics response of the structure and the transition function of the uniform theory of diffraction. The accuracy of the proposed solution is well assessed by comparisons with a commercial tool based on the finite element method.