CST Studio Suite 2025 SP2

Dassault Systèmes released the latest version of their 3D electromagnetic simulation software, CST Studio Suite 2025, in November ’24. It brings performance enhancements as well as new features to make sure that you can efficiently develop and optimize your future electromagnetic products.

Onboarding and Examples
When using simulations to make design decisions, it is crucial that you have set up your model correctly. To support and educate users, CST comes with multiple ‘getting started’ books, and the component library now contains more than 500 ready-to-run simulation models. These models provide insights into what can be done in the latest version of CST Studio Suite and how to start with your modeling and simulation setup.
SIMULIA ULM (unified licensing model)
A few years ago, Dassault Systèmes introduced the SIMULIA ULM. The unified licensing model is a more flexible licensing system, as it allows you to have a shared pool of compute licenses across all your SIMULIA products. The foundation of ULM is the compute tokens, which are used to cover your day-to-day needs. Tokens are checked out when running a simulation, and when the simulation is completed, the tokens are returned to the license pool. The same tokens are used whether you’re solving multiple jobs, using multiple CPUs, or multiple GPUs; whether you’re running electromagnetic simulations or, for example, structural simulations. In addition to tokens, you can also use credits, which are consumed on use. The number of credits consumed per hour depends on how many CPUs and GPUs you wish to use during your simulation. Typically, credits are used as a complement to tokens when you have a temporary peak in your simulation needs. When using the ULM, the front-end/GUI license will be valid for CST Studio Suite and, for example, Opera, Antenna Magus, Filter Designer 3D, and the recently acquired WASP-NET software. Additionally, EDA import functionality using e.g. ODB++ or IPC-2581 file formats in CST Studio Suite is also included in ULM. ULM tokens and credits are used as compute licenses for all these software programs.
Updates to Python CST apps
Even more Python CST apps are available in this latest release, bringing new features and enhanced performance. Many new methods are now available for writing your own Python scripts, especially when looking at PCB Studio and Design Studio (the schematic part of CST). When it comes to the 3D simulation studios/modules, most queries are available, including fetching results. 3D modeling is still done by embedding VBA code.
Antennas, RF components, and high-frequency solvers
Time domain solvers
- Floquet boundary condition to (narrowband) simulation of unit cell structures using T-solver
- Multiple simultaneous excitation lists can now be sequentially excited with the TLM solver
- Improved performance in the TLM discretizer and solver initialization for complex models
F-solver
- Performance improvements for the methods using tetrahedral mesh, in particular for curvature calculation during mesh generation and refinement
- Multi-frequency adaptive tetrahedral mesh refinement option for pre-defined frequency samples
- F-solver DDM (domain decomposition method)
. Further improved performance of the domain decomposition solver
. Automatic detection of similar domains for repetitions in the course of the domain decomposition solver start
Array task
- Time delay excitations for broadband beam steering
- Support to use existing array projects as subarray models
- ‘Simulation by zones’ is now also supported by the TLM solver
I-solver
- Adaptive surface mesh refinement
A-solver
- UTD (uniform theory of diffraction); higher-order contributions are now available
- Introduction of field source ports: Combined S-parameter and near-field surrogate model, enabling full IP protection. Allows for full far-field and S-parameter results in placement scenarios and advanced schematic-based workflows. Supported solvers for the placement domain include T-solvers (FIT, TLM) and the integral equation solver.
Additional design tools
- Antenna Magus, Filter Designer 3D, FEST3D, etc. are now included in the CST Studio Suite installer
- WASP-NET is now integrated into the SIMULIA ULM
- FEST3D includes a new exporting mode to CST Microwave Studio with CAD primitives, including parameters
EMC and EDA
- Importing PCBs is now quicker, especially on large boards. More control over details such as etch factor, solder mask, and more detailed via models. There are also feature improvements to operations such as bending PCBs.
- Improved flexibility when using Python for PCB import.
- When meshing advanced PCBs with tetrahedral mesh, this is now significantly faster.
- Another convenient feature for getting a quick overview of your board is the line impedance plot, which gives you a colormap plot showing the impedance along the selected traces. When using the thermal solvers, there are improvements in the electronics cooling ribbon for setting up fans, heat pipes, and field monitors.
- The pRLC solver now supports dispersive magnetic permeability, which might be of interest when modeling, for example, ferrites.
Low frequency
- There are additional feature enhancements on Litz wires.
- The low-frequency TD-solver now supports non-periodic linear motion scenarios that can be used when modeling, e.g., actuators.

#### General / 3D Modeling
- Upgraded 3D CAD import to support the latest import versions. **New Feature!**
- Adjusted locking behavior, if Mesh Fusion dialog box is directly closed.
- Corrected selection behavior in navigation tree if a new 1D result folder is created.
- Allow to export to DXF, Gerber and GDSII files without the need to select the shapes.
- Added support for HFSS import based on .AEDT and .SAB files.
- Fixed issue that message box might pop up when switching project sheets.

#### System Assembly and Modeling (SAM)
- The assembly modeler no longer prevents the 'DEL' key from working in the navigation tree.

#### EDA Import / EDA Tools
- Gerber Import: fixed import of aperture macro.
- Enhanced surface roughness setup in EDA stackup dialog box. Now a different roughness is possible on top and bottom sides of layers. Can be set layer wise and net wise. Extended the Python API. **New Feature!**

#### Distributed Computing (DC)
- Switch automatically to proxy mode for status connection if frontend cannot login to Solver Server. Prevent abort of solver in this case.
- Fixed abort of distributed optimizer run.
- Fixed DistributedComputing with SharedDirectory for SimulationProjects.
- Copy Export_Parametric folder for distributed parameter sweeps.

#### Post-Processing
- Fixed handling of transient results in Result3D.
- Fixed HDF5 export of CIR/PIC/TRK results.
- Improved ASCII export format for CIR results.
- Fixed wrong time values in field export of PIC position and PIC 2D results.

#### Visualization
- Fixed broken cutting plane for voxel models.
- Introduced stepped mode for Free color ramp. **New Feature!**
- Fixed Maximum time field monitor displayed on wrong surface.
- Fixed Export Field Plot to 3DEXPERIENCE.
- Improved cut plane behavior.

#### Non-parametric Optimization
- Feature the optimization over multiple operation points in the presence of eligible parameters.

#### High-Performance Computing (HPC)
- Added HPC Job Submission FE. **New Feature!**
- Disabled LSF CPU-GPU affinity for cluster utility scripts.
- Fixed queue/solver choice issue for HPC VBA macro.

#### Hexahedral (Hex) Mesh
- Improved memory estimation for calculation of matrix coefficients.
- Improved robustness for PBA/TST calculation.
- Fixed inconsistent PBA/TST setup.
- Improved check for CAD model insanities.
- Fixed numerical issue when calculating triangle-triangle intersections.

#### Tetrahedral (Tet) Mesh
- Reduced memory consumption during mesh creation.

#### CST Microwave Studio - General
- Fixed result template 'Convert all 1D Results from Frequency To Wavelength' for certain 1D result names.

#### CST Microwave Studio - Transient Solver (FIT)
- Floquet modes correctly consider TE/TM type when calculating s-parameters.
- Line impedance adaptation performs broadband sweep as soon as error criterion is met once.

#### CST Microwave Studio - Frequency Domain Solver (Tetrahedral Mesh)
- Fixed consideration of user-defined probe groups as convergence criteria in the mesh adaptation and in the broadband sweep.
- Fixed the parameter sweep in some special configurations.
- Improved the mesh refinement in presence of inhomogeneous materials.
- Fixed for field monitors in context of dispersive materials, fast reduced order model sweep.
- Fixed for low-frequency stabilization in context with surface roughness, fast reduced order model sweep.

#### CST Microwave Studio - Integral Equation Solver
- Added mixed solver order support for thin wire simulations. **New Feature!**
- Corrected solver settings, which were sometimes incorrect after a parameter change.
- Fixed performance issue with nearfield probe calculation.
- Fixed problem with different result at the same sampling point for RCS sweep.
- Added error handling when adaptive mesh refinement and wire mesh is combined.

#### CST Cable Studio
- Inserted missing flipping of single wire cables.
- Notify user interface when manually overwriting existing cable port via history list.
- Fixed visualization of cross sections for cables with drain wire.
- Fixed persistence of auto connect REF to 3D in the history list.

#### CST EM Studio - Partial RLC Solver
- Warn that nonlinear permeability is ignored by the solver.

#### CST Mphysics - General
- Fixed unit in Message window for relative permittivity (Drift-Diffusion Solver).
- Improved and stabilized convergence of Drift-Diffusion Solver.

#### CST Mphysics - Conjugated Heat Transfer Solver
- Fixed missing snapping tab in local mesh refinement dialog for the CHT Solver.
- Fixed thermal interface material on temperatures sources being ignored.
- Improved handling of dynamic axial fan intersections with solids.
- Support reloading of octree grids with more than 53M cells.
- Improved convergence for cases involving fluid cavities with high Prandtl number.

#### Spark3D
- Spark3D Task results are now invalidated if the associated Simulation Project changes.
- Fixed Spark3D Task error when running a Sweep task.

#### Fest3D
- Fixed issue in Fest3D GUI when connecting waveguide ports to Lat Coupling Cyl Cavity or Circular T junction elements.

#### CST PCB Studio
- Fixed linked SP updating for SI workflows.
- Fixed display and handling of package parts with identical names.
- Provide DDR4 & SI-TD EAT start time option. **New Feature!**
- Improved IR-Drop loading by caching repeatedly used objects.
- Provide new SI-TD differential terminations. **New Feature!**
- Handle expensive DDR4 table updates with a timer.
- Fixed issues related to layers of type 'Reference Plane'. They are now treated as 'Signal' layers. This fixed issues in line impedance plot and SI workflows.

#### CST Boardcheck
- Added two new Python commands: 'export_auto_tagging' and 'export_bck_rules'. **New Feature!**

#### CST Design Studio - General
- Resolved potential instability when performing IdEM vector fitting for blocks.
- Improved accuracy of power aware IBIS modeling.
- FD3D based optimizations will store S-Parameter plots in dB as a default.
- Implemented generation of missing Combine Results task results.
- Block result tree is now updated after combine results task run.
- Speed up parameter dependency check.
- Introduced heuristic to free up storage space. **New Feature!**
- Added missing 'Rename' context menu entry for probes and labels.

#### CST Design Studio - Interference Task
- Fixed display of a new worksheet when modifying a parameter in the Interference Tool.

#### CST Design Studio - Hybrid Solver Task
- Allow for mesh adaptation at arbitrary frequency in Hybrid Solver workflows. **New Feature!**

#### Filter Designer 3D
- Fixed wrong dimensioning prediction for both Resonator Round and Resonator Square from the Resonator Design Assistant.
- Fixed Filter Designer 3D causing DE to terminate when license not available.
- Fixed Filter Designer 3D requesting additional S2X license when launched from MWS.
- Upload custom components directly via CST Filter Designer 3D user interface. **New Feature!**

#### Automation / Macros / Result Templates / External Data Access
- Added python wheels for the cst.results package version 2025.
- Support non-ascii characters in Model3D.get_tree_items().

### Changes in 2025.01

#### General / 3D Modeling
- Corrected hybrid solver task setup, if protected models are involved.
- SOLIDWORKS Parametric Import: Allow importing of variables defined with comments.
- SOLIDWORKS and Siemens NX Import: Added VBA switch to disable importing of working planes. **New Feature!**
- Added 'Delete results' check to 3D CAD imports.
- Improved memory consumption of the Python menu.
- Fixed long project loading times for projects with many port meshes.
- Improved memory usage of Modeler executable, during Parameter Sweeps and Optimizer runs.
- Improved robustness in hardware detection, cgroup and processor group handling.
- Improved crash reporting by showing a message box pointing to the dump file location.

#### EDA Import / EDA Tools
- Importing IPC-2581 files with .xml extension failed on Linux.
- Improved healing of short segments and sliver gaps.
- Fixed drill-layer-span of buried vias for detailed via models.
- Soldermask cutouts were not considered, if axis-aligned area selection was enabled.

#### Distributed Computing (DC)
- Fixed issue CST DC Main Controller when enabling/disabling Remote Post-Processing feature in the Connected Solver Servers tab.
- When calculating a Simulation Project, the master project name is now also displayed in the job overview of the CST DC Main Controller. **New Feature!**
- Add DC files to cst project file.
- Fixed abnormal termination of CST DC Main Controller.
- Take machine file into account after 'Recover from job queue'.
- Fixed display of CST DC Solver Server reserved state.
- Delete Backupdirectory if older than 1 month.
- Fixed issue that changing the priority of a CST DC Solver Server set the running job id to the wrong solver server.
- Improved handling if reservation of CST DC Solver Server timed out.

#### Post-Processing
- Fixed wrong size of result array returned by Result3D VBA object under certain circumstances.
- Fixed wrong content of Farfield ASCII export under certain circumstances.

#### Visualization
- Improved Mesh View with Element Information.
- Fixed wrong position of Field Source plot under certain circumstances.
- Fixed broken Cross Section plot under certain circumstances.

#### Non-Parametric Optimization
- Set OK button as default in 'Domain Settings' dialog box.
- Fixed issue in verification step.
- Fixed issue if dispersive mu is used as background material.
- Fixed missing impedance data for verify step.
- Get correct tree names for single port excitation.

#### CST Microwave Studio - Frequency Domain Solver (Tetrahedral Mesh)
- Improved the port mode solver performance for cases with many waveguide ports.

#### CST Microwave Studio - Integral Equation Solver
- Fixed surface field plot when waveguide port is part of the simulation.
- Solid based fast monostatic RCS sweep: Add possibility to use it via file interface. **New Feature!**
- Improved simulation accuracy for simulations with waveguide ports.
- Make it possible to disable the snapping for 3D mesh adaptation.

#### CST Microwave Studio - Asymptotic Solver
- Improved accuracy for GO solver.
- Fixed an issue in the solver dialog box, when the frequency list is empty.

#### CST Mphysics - General
- Fixed Thermal losses post-processing template creation in EM-thermal coupled task.

#### CST Mphysics - Conjugated Heat Transfer Solver
- Fixed nonlinear materials handling in flow flux monitors.
- Fixed static axial fans being sometimes incorrectly marked as solids.
- Fixed dynamic pressure handling for dynamic fans at exterior boundaries.
- Fixed visualization of heat transfer coefficients.

#### Fest3D
- Fixed error on height limitation for input iris in Dual Mode synthesis.
- Fixed drag and drop project files in FEST3D UI when there is an already opened project.

#### CST PCB Studio
- Include RDQS as DDR5 ref option.
- Pass absolute DDR4 timing values to match CST DES results.
- Added current criterion for restricting refinement at vias. **New Feature!**
- Fixed PI performance issue.
- Pick DDR4 reference pins only from the same component.
- Only add really new package junctions to avoid duplicates.

#### CST Boardcheck
- Fixed that rule 'net crossing split' detected traces crossing solder mask shapes but should not.

#### CST Design Studio - General
- Fixed Spark3D task Edit behavior when Simulation Project uses Eigenmode solver.
- Fixed issue with Fest3D Block when reopening a valid .cst file that showed invalidated results.

#### CST Design Studio - Interference Task
- Fixed a bug that showed 0 channels in the list of transmitters and receivers for tasks in the Interference Tool.

#### Automation / Macros / Result Templates / External Data Access
- Fixed support for Python 3.11 with CST PCBS.