Surface waves in gyrotropic substrates

Theoretical considerations on surface waves in gyrotropic substrates are presented. In addition, an example of surface waves in a gyrotropic substrate is given. The example is for the case of a ferrite substrate that has a thickness of 2 mm, a dielectric constant of 12.6, a saturation magnetization of 2000 G, a bias H field of 1000 G, and that operates at 15 GHz. The direction of the bias field may be arbitrary. Therefore, the elements of the permeability tensor may all be nonzero. For the case under consideration, it is found there exist two surface wave modes, which are sensitive to the direction of the bias field. For an isotropic substrate, the dominant surface wave mode is a TM (transverse magnetic) mode, whose equiphase plane is a circular cylinder. For a gyrotropic substrate, it is seen that the dominant mode has a smaller propagation constant on the right-hand side of the direction of the bias field.<>