RF MODULE

Figure 3-18: The S 21 parameter (in dB) as a function of the frequency. This parameter is
a measure of the part of the wave that is transmitted through the elliptical port when the
waveguide adapter is excited at the rectangular port.
Modeling in COMSOL Multiphysics
This model uses the RF Module’s Port boundary condition for the wave propagation
problem. With this boundary condition the software computes the S-parameters
automatically. The mode of the incoming wave is specified. The mode of the outgoing
wave is given from an eigenmode analysis on the cross section of the elliptical part of
the waveguide adapter.
To create the geometry of the waveguide adapter from the command line, use the loft
command, which provides a smooth connection between the box and the ellipse. The
resulting geometry is available in a COMSOL binary file,
waveguide_adapter.mphbin. The script for creating the geometry is available at the
end of the model description.
WAVEGUIDE ADAPTER | 121