RF MODULE

Waveguide Optimization
Introduction
The optimization of components with respect to geometrical design parameters is a
common task in microwave engineering. In this model the reflection coefficient of a
waveguide structure is minimized, and the sensitivities of the real and imaginary parts
of the reflection coefficient are extracted using the parameterized geometry and
adjoint sensitivity features of COMSOL Multiphysics. The model was inspired by a
conference paper by Li and Nikolova (Ref. 1) and comparisons are made to that paper.
The example geometry is a waveguide 90-degree corner bend with the outer corner
replaced by a metallic wall section at 45 degrees angle to the connecting straight
waveguide sections.
Figure 2-2: 2D waveguide geometry with a 45 degree cut at the outer corner.
For a general introduction to the modeling of rectangular waveguide structures, see
the H-Bend Waveguide model on page 111 in the RF Module User’s Guide.
Optimizing the waveguide bend involves calculating how well a TE 10 wave propagates
between ports in the waveguide structure for different positions of the 45 degree wall.
WAVEGUIDE OPTIMIZATION | 31