This time, I show how to synthesize a waveguide bandpass filter in Fest3D. In this example, the filter uses irises to couple the cavities, but Fest3D can also synthesize filters using posts or E-plane strips.

After choosing the topology, we select the dimensions of the input and output ports. We then input the desired pass band, out-of-band response and filter order. We can choose some geometric properties of the cavities, such as whether the corners are rounded and which dimensions of the irises should be optimized.

The synthesized filter model is automatically opened in CST Studio Suite for analysis and/or post-optimization, which is typically not required.