Hi, I am really wondering about the magnetic boundary condition in CST high frequency simulations. It is a recommended setting for the simulation of microstrips with waveguides to support the QTEM mode. But when setting a magnetic boundary condition (Ht = 0) and checking the H-field with a field monitor, the tangential part of H ist not zero on the boundaries (nor is the normal elctric flux)! So the magnetic boundary is not adhered to. This really confuses me. Maybe someone can explain this and why one would set magnetic boundaries for a microstrip in the first place. I would be very grateful!

Here is an official result ready CST example with magnetic (Ht = 0) boundaries for a microstrip simulation:
https://www.3ds.com/products-services/simulia/resources/microstrip-transmission-line/