• Which Products are you interested in ?

    CST offers a wide range of EM simulation software to address design challenges across the electromagnetic spectrum, from static and low frequency to microwave and RF, for a range of applications, including EDA & electronics, EMC & EMI and charged particle dynamics.

  • Antenna Magus
  • IdEM
  • FEST3D
  • Optenni Lab
  • Looking for a Training, Workshop or eSeminar ?

    CST STUDIO SUITE® is being demonstrated at trade shows and workshops all over the world. Take a look at the list of conferences and exhibitions CST will be attending and get further information regarding CST workshops, eSeminars and training days.

  • TrainingsRegular training courses are held in CST's offices in Asia, Europe, and North America. Please check our trainings section for detail of trainings in all over the globe. Advance registration is normally required.

  • WorkshopsCST hosts workshops in multiple languages and in countries around the world. Workshops provide an opportunity to learn about specific applications and refresh your skills with experienced CST support staff. Make sure you visit our workshop section.

  • eSeminarsThroughout the year, CST simulation experts present eSeminars on the applications, features and usage of our software. You can also view past eSeminars by searching our archive and filtering for the markets or industries that interest you most.

  • Check our latest Events
  • Why create a MyCST Account ?

    A MyCST account may facilitate your access to many of the offerings on the CST website, for example the registration for eSeminars and the watching of eSeminars recordings, setting email preferences, and there is more functionality to come. It is required to participate in workshops and trainings.

  • Personal PreferencesAllows you to update your email preferences and areas of interest. It helps us to personalize your experience.

  • EventsSearch for events by location, industry and application. Once you are registered, you will be able to manage your registrations and check important details about your events. This section also provides you with a repository for Workshop & Training material.

  • LibraryYou can collect articles you find on the CST website to reference or read later by clicking on the “Add this article” button at the bottom of the article page.

  • Create Your Own Account
  • Need technical Support ?

    Customers can customize their accounts once they have completed the account creation process. This platform acts as vivid interface between CST and our customers.

    We therefore offer access to the latest Service Packs (including an automatic notification that a new Service Pack is available), a steadily growing database of Frequently Asked Questions (FAQs), Application Notes and Training Videos, as well as an individual FTP section for easy exchange of large files with our support team.

  • Do I need an Account?To access the Support Site a valid maintenance contract and a one-time registration is required.

    Please note that your Support login does not work for the MyCST account.

  • Get Support
  • How to request a Trial License ?

    Get your license in only three steps:

    1. Fill in the required fields in the contact form on the right and click "Send Us Your Request".

    2. Lean back and wait until one of our CST Experts contacts you.

    3. Enjoy a our trial license.

  • Student Edition

    Student Edition The CST STUDIO SUITE® Student Edition has been developed with the aim of introducing you to the world of electromagnetic simulation, making Maxwell’s equations easier to understand than ever. With this edition you have, bar some restrictions, access to our powerful visualization engine and some of the most advanced solvers of CST STUDIO SUITE.

    Student Edition

CST – Computer Simulation Technology

TLM Solver


The TLM solver of CST MICROWAVE STUDIO® (CST MWS) is based on the 3D time-domain Transmission-Line Matrix (TLM) method. Developed over a period of more than 40 years, TLM is a well established method and offers particular advantages for EMC/EMI applications.

TLM can be classified as a full-wave, volume-meshing technique. Maxwell’s equations are rigorously solved in space and time. TLM uniquely uses a network of transmission lines or “nodes” to model electromagnetic fields locally in each hexahedral cell of space. A volume of space is modeled by a 3D array of such nodes. The solver runs an explicit time stepping algorithm. At each time step, pulses incident on the nodes are reflected according to the scattering matrix of the node and then connected to neighboring nodes. Electric and magnetic field components are derived from combinations of pulses.

TLM Node and Mesh

The CST MWS TLM solver uses a multi-grid formulation. The hexahedral mesh is first refined or graded to capture detail in the geometry. Small mesh cells are subsequently automatically combined or “lumped”, the level of lumping increasing with distance from geometric boundaries. This process removes any “bleeding” in the mesh, minimizing the cell count and reducing computer requirements to the absolute minimum. The end result is a multi-level Octree mesh. In many cases, the total number of mesh cells is reduced by over 90%.

The CST MWS TLM solver has been enhanced to include "compact modeling" technology. In EMC/EMI applications, objects with relatively small dimensions, such as slots/seams, vents, multi-wires, shielded cables, have a big impact on the performance of the system. Compact modeling enables these critical features to be represented by equivalent transmission-line models; it is not necessary to use a fine mesh to capture the small dimensions. Unlike many modeling techniques, the compact models are fully integrated into the electromagnetic field solution. Compact modeling can reduce the computer requirements by several orders of magnitude.

As previously stated, CST MWS TLM solver is a time-domain approach enabling a full-spectrum analysis to be performed through a single solve. This makes it ideal for broadband antenna design and EMC/EMI problems which can cover huge frequency ranges. The time-domain solver can be used to directly simulate transient phenomena such as EMP and lightning. In these applications it is often beneficial to visualize the flow of currents and propagation of fields in time and to determine the peak induced voltages/currents in internal cabling.

Integration of the CST MWS TLM solver into the CST STUDIO SUITE® now enables tight, bi-directional coupling with CST CABLE STUDIO® and CST DESIGN STUDIO™. It is possible to run the 3D TLM field solver in true transient co-simulation with CST CABLE STUDIO® and CST DESIGN STUDIO™. This offers unique and ground-breaking electromagnetic simulation capability for engineers facing challenging EMC/EMI and antenna problems.

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