CSC - A procedure for coupled S-parameter calculations

Large rf-structures are sometimes too complex to be calculated entirely in single simulation runs. Usually, if the structure has open ports, the scattering properties - the so-called S-parameters - are of primary interest. As a matter of fact, they can be derived from scattering properties of parts of the entire structure, which are calculated in the procedure presented here in separate, less expensive simulations. A very compact representation of the underlying theory was found, which is presented in the paper. Furthermore, a Mathematica application called CSC based on this formulation is introduced. CSC calculates the scattering properties of an object, which are a combination of an arbitrary structure of segments with previously calculated S-parameters. To illustrate the use of CSC, three examples are shown: higher order mode (HOM) coupling properties of components of the TESLA Test Facility without and with accelerating cavities and the coupling of polarizations in chains of structures with slight deviations from circular cross sections.