Using metamaterials to exploit lateral waves for RF microwave applications

In this paper, the excitation of lateral (surface) waves in a layered media consisting of a ground plane, a metamaterial layer and free space is investigated. It is presumed an effective media approximation yields the anisotropic constitutive parameters for the metamaterial layer. Using these approximations, Green´s functions are developed for the electromagnetic fields resulting from a Hertzian dipole excitation located at the metamaterial and free space interface. As the formulation of the problem is accomplished in the spectral domain, the strength of the lateral waves is found from the residues of poles circled in the complex plane. This is first done for the case of an anisotropic media in the x- and y- directions (parallel to the ground plane). Because the unit cell patterning of the metamaterials gives the microwave designer increased flexibility, it is possible to undertake a similar analysis using anisotropic constitutive parameters expressed in cylindrical coordinates. This analysis is fundamental for applied microwave applications such as the realization of an antenna on a layered media and demonstrates the enormous design flexibility made possible for metamaterials.