Dyadic Green's functions for unbounded and two-layered general anisotropic media

The dyadic Green's functions (DGFs) for unbounded and layered general anisotropic media are considered in this paper. First, the DGF for unbounded problem is derived using the eigen-decomposition method. Two different approaches are proposed to obtain the DGF for layered problem when the source is located inside the anisotropic region. The first approach is to apply the modified symmetrical property of DGF to obtain the DGF for the field in the isotropic region when the source is located inside the anisotropic region, from the DGF for the field in anisotropic region when the source is in the isotropic region. This modified symmetrical property can be applied for the layered geometry with bounded anisotropic region being either reciprocal or non-reciprocal medium. However, this method can not give the DGF for the field inside the anisotropic region. Thus, the second approach is presented to obtain the complete set of DGFs for all the regions including the anisotropic region, by applying the direct construction method through eigen-decomposition together with matrix method.