Closed form expressions for Green's functions of microstrip structures on a uniaxially anisotropic substrate

Closed form expressions for the Green's functions of a planar microstrip structure on an electrically thin uniaxially anisotropic substrate have been derived. The approach is to first obtain the quasi-dynamic term and refine its accuracy with a correction term valid for higher frequencies. The quasi-dynamic term conveys the influence of partial images and includes both transverse and vertical dielectric constants ε_rt and ε_rz. The correction term, on the other hand, results in an expression that includes ε_rz only. Results indicate excellent agreement with exact numerical solution over a significant band of frequencies and over a large range of spatial values.