Modeling of planar circuits including the effect of space-varying surface impedances

Microstrip circuit calculations including the effect of lumped impedances can be carried out by describing the lumped elements mathematically with the help of Delta -functions. This approach is based on the assumption of impedances with infinitesimally small extension in one dimension. This approach is generalized for impedances of finite extent. Space-varying surface impedances are introduced that are incorporated into the mixed space-spectral domain analysis. The circuit is embedded in layered media and is fed by an arbitrary number of planar lines. Examples for microstrip lines with an absorbing impedance region are given.<>