Eigenmode calculation of complex RF-structures using S-parameters

This paper presents a technique to calculate eigenfrequencies and the corresponding field patterns of complex rf-structures or beam pipe sections in particle accelerators by subdividing the total section, calculating the distinct scattering parameters and then combining the results of the subsections. This allows a reduction in the effort of a single calculation step to a practical amount and the possibility to exploit the symmetry and multiplicity of some parts of the structure