CAD Model for Microstrips on r-cut Sapphire Substrates

Artikel i vetenskaplig tidskrift, 1994

Simple and correct formulas are derived for calculation of an effective isotropic dielectric constant, which characterizes the wave propagation in microstrip lines on anisotropic substrates made of r-cut sapphire crystals. The r-plane is extensively used for epitaxial growth of high-Tc superconductor YBa2Cu3O7 films as applied to microwave integrated circuits. In contradistinction to previous models developed for z-cut sapphire, the nondiagonal dielectric permittivity tensor of r-cut sapphire is used. The effective dielectric constant of a microstrip line on r-cut sapphire substrate is found as a function of the strip-line geometry and the orientation of the crystallographic axes with respect to the symmetry plane of the microstrip line