Microstrip Cross-Coupled Filter Design

This presentation builds on a previous webinar where we designed a microstrip combline filter. In this webinar we will explore adding a cross-coupling to the microstrip combline. We will add a capacitive cross-coupling that will produce a transmission zero on the low side of the passband. There are several ways to physically realize the desired cross-coupling. We will explore these options before choosing the final physical realization.

Sonnet em will be used to analyze our planar filter in a cutoff waveguide channel. We will add an extra port to each resonator in the Sonnet em model so we can port tune the EM simulation results using NI Microwave Office and EQR_OPT_MWO from SW Filter Design. This combination of tools will allow us to rapidly try different configurations for the desired cross-coupling. Once we settle on a topology, we will “grow” the cross-coupling into our filter layout using optimization. The combination of port tuning and robust, repeatable optimization makes this a very simple and intuitive design process.

Who should attend:

This material is suitable for filter designers, RF component designers, system engineers, experienced technicians and technical managers. Some previous experience with Method of Moments field-solvers would be helpful but is not required. Math skills above basic algebra are not required. The emphasis is on practical, proven procedures that are easy to follow rather than filter theory.

Presenter Bio:

Daniel G. Swanson, Jr., General Partner, SW Filter Design, Boulder, Colorado, USA. Mr. Swanson received his BSEE degree from the University of Illinois and his MSEE degree from the University of Michigan. He has designed broadband amplifiers, various types of oscillators, thin-film filters and high Q cavity filters for both military and commercial applications. He is currently developing software tools for filter design and optimization with his partner Bob Wenzel. Mr. Swanson is the principal author of Microwave Circuit Modeling Using Electromagnetic Field Simulation. He is presently teaching several continuing education courses on filter design and EM simulation. Mr. Swanson is a Fellow of the IEEE and has served the IEEE MTT Society in many capacities.