A.R. Kerr
January 7, 1999
Keywords: microwave circuits, electromagnetic simulators, conductors, surface impedance
Electromagnetic simulators can give very accurate solutions for microwave circuits with ideal conductors. When the conductors are non-ideal, accurate results may still be obtained in many cases by specifying material parameters or surface impedances. However, for structures in which the penetration depth of the field into the conductors is of the same order as the conductor thickness, considerable error can occur. This is not only a result of the conductor thickness being insufficient to contain the field completely, but is due in part to a separate effect which arises with some EM simulators when thick conductors are represented by thin sheets with surface impedance. For superconducting niobium microstrip circuits of typical dimensions, such errors can easily be as great as 20% in eff and 10% in Z0. In many cases, a simple correction to the surface impedance substantially improves the accuracy.Last modified: 09 December, 1999
kweather@nrao.edu