The Eigenmode Solver of CST MICROWAVE STUDIO® (CST MWS) is dedicated to the simulation of closed resonant structures. Primary results are, besides the field distribution of the modes, the eigenfrequencies of the structures. The Eigenmode Solver also takes advantage of CST's proprietary PERFECT BOUNDARY APPROXIMATION (PBA)®, which delivers fast convergence in short time.
Typical application areas are the determination of the poles of a highly resonant filter structure, Q-value (also external) calculation, and the design of slow wave structures (like Travelling Wave Tube (TWT) or accelerating cavities).
Magnetic field inside a helical slow-wave structure as used in Travelling Wave Tubes (TWTs).
There are two solvers available: the Advanced Krylov Subspace method (AKS), and the Jacobi-Davidson method (JDM). The AKS solver calculates efficiently a number of modes with the lowest resonant frequencies in lossfree structures. The JDM solver can also be used to calculate non extremal modes at an arbitrary position inside the spectrum. In addition the JDM solver can include even highly lossy materials.
The Eigenmode Solver also features periodic boundary conditions and supports the automatic creation of dispersion diagrams.CST MWS Eigenmode Solver application examples