Surface Wave Propagation on Bianisotropic Metasurfaces by Using Electric and Magnetic Polarizabilities

In this paper, we study the existence of a surface wave on bianisotropic metasurfaces (BMS) by using electric and magnetic polarizabilities. These polarizabilities connect the local electric and magnetic fields on BMSs with electric and magnetic surface polarizations. We have chosen the method based on surface polarizations because applying boundary conditions using surface polarizations gives a better physical insight than the other methods including surface impedance-based methods. Variations of the electric and magnetic surface polarizations are equivalent to electric and magnetic surface currents, respectively; so, the Variations lead to discontinuities of the magnetic and electric fields on the BMS's surface. In BMS structures, one of the challenges is the cross-polarization between TE and TM modes, because of both the anisotropy and bi-isotropy of these structures. Using the electric and magnetic polarizabilities gives a better physical insight to the cross-polarization. To obtain surface wave excitation conditions, on a general BMS in the presence of an electric line source, we should firstly apply the boundary conditions and obtain the unknown coefficients in terms of the electric and magnetic polarizabilities. In the last step, we extract the dispersion equation by using the polarizabilities. To verify the results we have simulated an array of Ω-particle metasurface and a planar periodic array with non-identical coupled square conducting patches imprinted on two sides of a dielectric slab. The comparison between the dispersion curves obtained with the theoretical method and the simulation results reveals an overall good agreement.