The frequency domain solver is, like the transient solver, a general purpose tool. It delivers electromagnetic near and farfields as well as S-Parameters. Although the line cannot be drawn easily and there are always exceptions, the Frequency Domain Solver is the better choice, if you are looking at electrically small structures, or devices with a high Q-value.
As an unique feature, the frequency domain solver can be switched from Cartesian to tetrahedral meshing. Besides segmented representation of curved surfaces, a true surface mesh as shown below increases accuracy and speed.
Mesh refinement of traditional tetrahedral frequency domain solvers does not improve upon the initial faceted representation of the structure. The True Geometry Adaptation projects the refined mesh back onto the original model to achieve higher accuracy.
CST Studio Suite allows the user to alternatively use the Time Domain or the Frequency Domain solver on the same simulation model.
Broadband results are provided quickly with the built-in adaptive frequency sweep. For both mesh types, automatic mesh adaptation schemes are implemented. The frequency domain solver offers a direct and an indirect linear equation system solver. The direct one is preferable if the number of tetrahedrons is not too large; it shows its main strength when the full S-matrix of a structure with multiple excitations is required.
A key application for the Frequency Domain Solver are periodic structures, suche as PBGs, FSSs, or phased arrays. CST Studio Suite features a special periodic boundary implementation, which automatically creates the boundaries for arbitrarily shaped unit cells. The ports are equipped with Floquet-mode solvers for highly accurate and fast simulation, and the easy analysis of polarization and mode type.
A circulator simulated with the CST Studio Suite Frequency Domain Solver.
The Frequency Domain Solver can be used for frequency dependent, anisotropic media. For circulator ferrites the biasing can be calculated using the magnetostatic solver. The port orientation is arbitrary.