Hello,

To determine modal weighting coefficients in CST Microwave Studio (CST MWS), you need to perform a Characteristic Mode Analysis (CMA) and then analyze the modal significance and currents. The process involves defining a structure, selecting a solver, running the CMA, and then interpreting the results to understand how each mode contributes to the overall antenna behavior.

Here's a more detailed breakdown:

1. Define the Structure and Solver:

• Create or import your antenna structure in CST MWS.
• Choose the appropriate solver for your simulation. For CMA, the Eigenmode solver is typically used.
• Set up the simulation parameters, including frequency range and desired accuracy.

2. Perform Characteristic Mode Analysis (CMA):

• In the solver settings, enable the Characteristic Mode Analysis (CMA).
• Specify the frequency range for the analysis and any other relevant parameters.
• Run the simulation. CST will calculate the characteristic modes of the structure and their corresponding eigenvalues and eigenvectors.

3. Analyze the Results:

• Modal Significance:Examine the modal significance (MS) for each mode. MS indicates how strongly a particular mode contributes to the antenna's overall behavior. A higher MS generally means a stronger contribution.
• Modal Currents:Visualize the modal currents for each mode. This helps understand how current flows on the antenna structure for each mode and how they relate to the overall radiation pattern.
• Modal Weighting Coefficients (MWC):While not always explicitly named, the modal weighting coefficients are essentially the magnitudes of the modal currents. You can extract these values from the simulation results, often by examining the current distributions for each mode.
• Interpretation:Compare the MWC values for different modes. Modes with higher MWC values contribute more to the antenna's performance at a given frequency.
• 4. Design and Optimization:
• Based on the CMA results, you can identify which modes are most relevant to your design.
• Use this information to guide your antenna design, such as selecting appropriate feed positions or modifying the antenna geometry to enhance the excitation of desired modes.
• Iteratively refine your design and re-simulate until you achieve the desired performance.

In essence, the modal weighting coefficients are derived from the analysis of modal currents, which are a direct output of the CMA. By understanding how these currents contribute to the overall behavior of the antenna, you can gain valuable insights into its performance and optimize its design.

Thanks,

Greetings Smrity Dwivedi professor, professor once identified the relevant modes for our antenna design should we change the solver back to time-domain in CST to verify the same (results) and, for exporting its gerber file for fabrication.

How to extract MWC from cst . Process for.MWC