Propagating and evanescent modes in two-dimensional wire media.

Electromagnetic waves in an artificial medium formed by two mutually orthogonal lattices of thin ideally conducting straight wires (referred to as a two-dimensional wire medium) are considered. An effective medium approach and a full-wave method based on the dyadic Green's function and the method of moments are developed. Effects of spatial dispersion, such as the appearance of anisotropy in a square lattice and an additional extraordinary wave, as in crystal optics, are demonstrated. Evanescent waves with complex propagation constants are found. The case when both forward and backward extraordinary waves with respect to an interface exist simultaneously is observed and discussed. The effect of birefringence, so that one extraordinary wave has the wave vector making a positive angle to the interface and the other has the wave vector making a negative angle to the interface, is illustrated.