This article is a practical guide on how to feed a waveguide dielectric resonator filter.

As an example, we will look at a waveguide filter with dielectric resonators solved using the finite element method (FEM). The outer waveguide faces are set to perfect electric conductor (PEC).

The dielectric resonator filter model.

 

 

The dielectric resonator filter model with mesh with an active cutplane showing the FEM dielectric regions.

 

Since this shielded waveguide filter is a non-radiating microwave component containing dielectric regions, the example is well suited to be solved using FEM. For this example [1], the waveguide structure will be excited using a waveguide port.

A good approximation of the physical model is to place the waveguide port in the plane where the waveguide transitions into the coaxial adaptor. The waveguide port must cover the full cross-section of the face. Boundary edges forming the port shape must be set to PEC.

To excite the filter:

• Select one of the two faces at either side of the filter where the waveguide would transition into the coaxial adaptor.

A face is selected on one side of the filter.

 

• Add a waveguide port to the first selected face.

A waveguide port is added to the filter.

 

• Select the second face at the side of the filter where the waveguide would transition into the coaxial adaptor.
• Add a waveguide port to the second selected face.
• Add an S-parameter configuration and make Port 1 active to calculate the S-parameters between the two ports.

 

See Ports and sources in Feko for more information on ports, sources as well as practical examples on how to feed typical structures in Feko.

 

References:

[1]: Hiroshi Shigesawa et al., “Two-path cutoff waveguide dielectric resonator for filters”, IEEE Trans. Microwave Theory and Techniques, vol. 7, pp.1105-1112, July 1989.