Couplings Designer

Design and synthesize modern advanced RF and microwave filters with Couplings Designer for iPhone and iPad, available at the app store, or try Couplings Designer LITE for free.

Truly versatile filter design:

  • Cavity, dielectric, coaxial, planar or lumped filters, in fact all coupled resonator technologies
  • Bandpass, bandstop or multi-band filters
  • Diplexers, multiplexers
  • High rejection and/or group delay equalized responses
  • Arbitrary filter topologies, support for modern NRN-based designs
  • Predistorted filters

Couplings Designer features an easy to use interface, bandpass/bandstop synthesis with prescribed zeros and predistortion, non-resonating nodes, tuning, a built-in coupling matrix optimizer, Monte Carlo tolerance analysis and an arbitrary topology transformer. It’s an ideal tool for professional filter engineers, system engineers and students alike.

Try Couplings Designer LITE for free on your iPhone or iPad!

Couplings Designer allows efficient design of advanced RF and microwave filters using any given technology. A powerful hybrid synthesis technique taking advantage of both exact polynomial approximation with prescribed zeros and optimization reduces the time and effort required to find an optimum coupling matrix. The full range of zeros available for a given filter order and topology are easily engineered to fit your specification. The synthesized coupling matrix can be realized as lumped components, distributed elements, waveguide structures or any exotic resonator and coupling mechanism imaginable.

Key features include:

  • bandpass or bandstop response
  • synthesis with prescribed zeros
  • predistortion
  • non-resonating nodes, NRNs
  • cascading of designs (modular filter design)
  • an advanced optimizer
  • an arbitrary topology transformer
  • Monte Carlo tolerance analysis
  • tuning of individual or symmetrical couplings
  • couplings are represented as physical or normalized
  • markers and handy multi-touch gestures for scaling plot axes
  • export matrix and S-parameter data

A suitable coupling matrix and topology is found within minutes. A typical design flow with Couplings Designer consists of:

  • setting up goals, or in other words filter specifications, based on rejection, ripple and group delay requirements
  • specifying a filter order, bandwidth, center frequency and resonator quality
  • synthesize a seed coupling matrix that may include prescribed zeros and/or predistortion
  • transform to a topology suitable for implementation, arbitrarily specified or using built-in presets (folded, arrow, cul-de-sac, extended box)
  • manual tuning and/or optimization
  • tolerance check using Monte Carlo analysis
  • export the design to a computer
  • realize the coupling matrix using computer software or empirical methods

This tool is not limited to filter experts only, an engineer without previous knowledge of coupling matrices and advanced filter design can instantly get a picture of what’s doable without having to consult an expert. Students can interactively learn how couplings affect the filter response and gain a better understanding of modern filter synthesis. Couplings Designer is also a great tool for backward engineering a filter when doing post-manufacture tuning. Brainstorming around a new filter is no longer limited to guessing, Couplings Designer can give you accurate information and is available to you at any location on your iPhone or iPad.

Learn about features available in Couplings Designer and take a tutorial on how this tool can assist you in your filter designs.

More video tutorials on filter synthesis

A demonstration of advanced filter synthesis concepts that can be applied to your future designs to meet the demand for stringent requirements. Couplings Designer makes it easy.

  • Transmission zeros – the importance of transmission zeros and how they can be engineered to create advanced filter responses for increased rejection and/or group delay equalisation.
  • Non-resonating Nodes, NRNs – the relatively new building block, a non-resonating node or NRN, can be used to create new advanced filter topologies.
  • Predistortion – the benefits of predistortion when size and cost requirements are stringent.
  • Resonator Q distribution – the importance of distributing the resonator Qs correctly when reducing the size of a filter implementation.
  • Topologies – the concerns involved in choosing an appropriate topology, especially the sensitivity issues inherited in certain topologies.
  • Optimization – the power of combining two synthesis methods, exact approximation with prescribed zeros and optimization, to synthesize a coupling matrix according to a specification.

9 Responses to Couplings Designer

  1. saeed says:

    thank you very mutch

  2. BC Kim says:

    Thanks for demo Video. It’s quite impressive to me. I’m engaged in company for Filter product.
    Is there a Android version ‘Couplings designer’?
    If there is not Android version, do you have plan to make Android version?
    Please notice me.

    • Thanks! You don’t have an iPhone/iPad and want to run something similar on Android? Or are you interested in developing a synthesizer for Android? I’m quite busy with improving the iOS version but I’ve been thinking of releasing something stripped down and simpler for a number of platforms. Which features of Coupling Designer would you like to see in a multi-platform version?

  3. Nam says:


    I’m using the free trial version and I can’t scroll up on the response graph is there a way to enter the max and min of the x and y axis?

    • Hi,
      Yes, if you tap the options button you will see a hint on how to use the interface. Just scroll or pinch the axes (darker areas) on the response plot to adjust them. If you double tap on them they will autoscale. For instance if you want to zoom in on the passband ripple you can pinch and scale the frequency to only include the passband and then double tap the s21 axis. You can read more about the interface in the documentation here on this site.


  4. Kevin says:

    Dear Goran
    Thank you for a very impressive program. I just purchased the full version and are having trouble exporting a filter or synthesizing it. When I export the filter or synthesis it the app crashes. I am running os 7.1 is this “bug” of not synthesising properly related to my ipad running version 7.1
    Also after I try and synthesis the filter or export it. The filter response disappears

  5. kevin says:

    hi, is the app still being maintained or is it abandoned?

    • Hi Kevin, it is not abandoned but haven’t had the time to update it for a while. Once in a while I add user requested features and sometimes Apple does radical changes to the OS that requires changes to the software to function properly. It’s working very well in its current state but when I have the motivation and time why not add some new great stuff.

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