RF Module

Engineers working with wireless equipment can benefit significantly from the finite element modeling of electromagnetic waves. They can correlate important engineering parameters such as impedances, radiation patterns, and S parameters to antenna geometries and obstructing objects. This document contains four examples of electromagnetic wave models you can build from scratch in the RF Module for COMSOL Multiphysics.

• The first model shows the transition between a rectangular and an elliptical waveguide. It uses the RF Module’s boundary mode analysis to determine the shape of the wave that leaves through the elliptical window. It calculates the scattering S-parameters that measure the transmission and reflection of the wave.
• The second example is a conical antenna where axial symmetry reduces the problem size. It shows many of the features in the RF Module that are important for antenna design including S-parameter analysis, frequency sweep, and far-field calculations.
• The third model demonstrates a nonreciprocal microwave component. A small cylinder of a gyrotropic material in a three-port waveguide junction causes it to act as a matched coupler for waves propagating in in one direction and an isolator for waves propagating in the other direction.
• The final example models thermal drift in a microwave filter. This multiphysics model uses three application modes: shell expansion, moving mesh, and electromagnetic waves. It also employs the powerful COMSOL Script language to perform some of the steps.