Hybrid Mode Analysis of Microstrip Lines on Anisotropic Substrates

A rigorous hybrid mode analysis is applied to the microstrip line on anisotropic substrate to determine its high frequency performance. The treatment is limited to substrates with uniaxial anisotropy with the principal axis perpendicular to the surface. This includes the practically important case of microstrip lines on Sapphire. The exact results obtained are used to check the validity of the previously introduced concept of equivalent isotropic substrate, which was used by some authors to simplify the calculations of the high frequency parameters of such lines .