Cavity Eigenfrequency Modeling Using the Electromagnetic Waves, Beam Envelopes Interface
Application ID: 58961
This model demonstrates three different ways to find the eigenfrequencies of a rectangular metallic cavity.
The first method uses an eigenfrequency study step together with the Electromagnetic Waves, Beam Envelopes interface. Here, it is important to define a wave vector for the physics interface that is independent of the eigenfrequency (eigenvalue). Otherwise, the accuracy of the solution will be bad.
The second method uses a nonlinear eigenfrequency setup, together with the Electromagnetic Waves, Beam Envelopes interface. This method is also used in the Wave Optics Module Application Library model Transverse Modes for a Symmetric Laser Cavity and is included for comparison with the first method.
The third method uses an eigenfrequency study step together with the Electromagnetic Waves, Frequency Domain physics interface. It is demonstrated that a much finer mesh is required for this physics interface to obtain the expected eigenfrequencies.
A second model is also included, where the simple rectangular cavity has been slightly modified using two central metallic protrusions. This perturbs the modes and requires finer meshes, but all three methods produce similar results.
This model example illustrates applications of this type that would nominally be built using the following products:
however, additional products may be required to completely define and model it. Furthermore, this example may also be defined and modeled using components from the following product combinations:
The combination of COMSOL® products required to model your application depends on several factors and may include boundary conditions, material properties, physics interfaces, and part libraries. Particular functionality may be common to several products. To determine the right combination of products for your modeling needs, review the Specification Chart and make use of a free evaluation license. The COMSOL Sales and Support teams are available for answering any questions you may have regarding this.