The frequency-domain solver implemented within the InventSim framework is a versatile finite element package designed to address electromagnetic problems across various domains. These challenges arise in the analysis of microwave junctions, filters, couplers, multiplexers, and antennas. The finite element method (FEM), a computational electromagnetics technique, stands as a robust solution capable of accurately solving Maxwell’s equations for intricate, user-defined structures containing inhomogeneous media. FEM is particularly suited for resolving problems with electric dimensions within the range of a few tens of wavelengths. As such, it serves as an ideal solution for designing complex components of medium scale, such as high-order filters, multiplexers, or antenna arrays.

Main features of the computational kernel:
- High order basis functions for accurate approximation of electromagnetic fields,
- Second order curvilinear elements for accurate modeling of curved geometries,
- Applies unstructured tetrahedral elements ideal for complex shape modeling,
- Automated mesh generation,
- Two methods to solve arising system of linear equations: direct or iterative
- Direct solver based on matrix factorization (Intel MKL Pardiso) is fast but more memory consuming, ideal for frequency sweeps,
- Iterative solver with an efficient multilevel preconditioner enables fast convergence and limits the maximum memory needed to solve the problem. Ideal when large problems are solved at a few frequency points.
- Fast frequency sweep method based on model order reduction technique giving results with guaranteed accuracy comparing to point-wise, direct frequency sweep
- Interpolating sweep based on rational interpolation of system response
- Mixed precision solver for memory limited systems
- Direct near-to-far field transformation available giving maximum accuracy of radiation pattern analysis