Combline Synthesis

Combline Filters Synthesis Wizard (CFSW) for narrow- and broad band filters

1. General

The Combline Filters Synthesis Wizard (CFSW) allows a fast synthesis and optimization of narrow- and broadband combline pass band filters by using the mode-matching technique for the multimodal computation. The simulation is provided by Mician's Mirowave Wizard. The CFSW uses a novel technique for the synthesis of the coupling coefficients and a new efficient optimization method.
The filters can be of type inline or folded. In case a of narrow band filter the cavities are separated by irises where each iris can include finite radii for milling purposes. In case of a broadband filter the design consists of  posts only.

 

Fig.1. Example of an inline combline filter for narrow and broad band applications.

2. Synthesis and optimization

After starting CFSW the main window appears as shown in Fig.2. The window allows the setup of the filter specifications. The design of the filter is straight forward. From the users side it is required to go through all tabs and to add the required parameters to the entries until all check marks are green.

 

Fig.2. Main window

 

During the synthesis a plot window shows continously the improvements and the value of the error. After an successful synthesis and optimization  the initial filter parameters are assigned directly to a Microwave Wizard project. All elements, empty waveguides, variables and optimization goals are set automatically. An analysis in Microwave Wizard will show the previouse shown optimized curve again.If required a short post optimization can be done by using the built-in optimizers of Microwave Wizard.


Fig.3. Folded filter design analyzed by Microwave Wizard after the synthesis by the CFSW tool.