Check the mesh carefully. This error is usually caused by a meshcell that contain 1D or 2D PEC unit and do not resolve it.

Hello,

In CST Microwave Studio, the "partially filled with PEC" warning indicates that a simulation domain contains a perfect electric conductor (PEC) material that is not fully enclosed within the simulation space. This can lead to inaccuracies in the simulation results, potentially causing a mismatch between simulated and fabricated designs.

Here's a more detailed explanation:

What it means:

• PEC:A perfect electric conductor is a theoretical material that perfectly reflects all electromagnetic waves. In CST, it's used to model highly conductive materials like metals.
• "Partially filled":This means the PEC object doesn't completely fill the simulation volume or a defined domain. Imagine a metal plate that doesn't extend to the edges of your simulation box, or a metal object that doesn't fully enclose a volume within the simulation.

Impact on simulation:

• Potential for inaccuracy:Because the PEC isn't fully contained, the simulation might misinterpret how electromagnetic waves interact with it. This can lead to incorrect field distributions and S-parameter calculations.
• Mismatched results:If you're designing an antenna or other microwave component, this inaccuracy could cause your simulated results to deviate significantly from what you'd see in a real-world fabrication.
• Unrealistic behavior:The warning suggests that the simulation might not accurately represent the intended behavior of the PEC component, potentially leading to unexpected simulation results.

How to fix it:

In essence, the "partially filled with PEC" warning is a signal that your simulation setup might not be accurate. Addressing the issue by ensuring complete enclosure or using appropriate boundary conditions will lead to more reliable simulation results.

Thanks,

Based on my industry-level simulation experience, this factor typically doesn’t have a significant impact. However, it’s crucial to properly review and refine the structure's mesh, especially for small slots inside the antenna, as insufficient meshing in these areas can lead to shorting issues. I recommend starting with a lower global mesh setting to optimize simulation time, and if further refinement is needed, apply local meshing to critical regions to achieve the required accuracy more efficiently.