Time-to-Frequency Fast Fourier Transform of a Coaxial Low-Pass Filter

Application ID: 43851

A very wide band coaxial low-pass filter is designed using a 2D axisymmetric model. To address the wide band frequency response with a fine frequency resolution, the model is built with a transient physics interface first. Then, S-parameters are calculated using a time-to-frequency Fourier transform.

To achieve a low-pass frequency response, an air-filled coaxial cable is tuned with five annular rings (irises) that are added to the outer conductor wall in this example model. The coaxial cable walls and iris parts are modeled as perfect electric conductors (PEC). The volume inside the center conductor of the coaxial cable is removed and only the conducting metal surfaces are modeled.

The computed S-parameters show a low-pass frequency response with a cut-off frequency around 24.5 GHz.

This model example illustrates applications of this type that would nominally be built using the following products: