Coupling Matrix basics

This page is being updated, stay tuned!

In the meanwhile…have a look at Microwave Journal’s article on advances in microwave filter design techniques. Their article highlights the benefits of using modern coupling matrix techniques to design advanced and versatile RF and microwave filters.

Another great source for those new to filter design is which is a blog devoted to RF and microwave filter theory.

You may also find these books useful and a source of inspiration for taking your designs forward.

Back to the Couplings Designer documentation.

4 Responses to Coupling Matrix basics

  1. Kamysteven says:


    Can tell how can I desing 90 and 180 degree hybrid coupler ?

    I have you app is the good.


    • Hi,
      Couplings Designer can only be used to analyze two-port circuits or circuits that can be reduced to two-port sub blocks like diplexers. To synthesize your resonator-based hybrid coupler which has four ports you need a matrix that has couplings (loading) to all ports. The matrix can be equivalently analyzed to retain the s-parameters as is done for a normal two port matrix but for each signal path, 1 to 2, 1 to 3, 1 to 4 etc. I guess you would have to write your own code since I’m not sure if there’s any commercial coupling matrix synthesis software that supports multiple ports. You may want to read a very nice phd thesis on this subject:

      hope I could be of any help and thanks for using my app 😉

  2. Kamysteven says:


    Thank you so much for you advice and help.

    Do you have a more info about coupler 90 and 180degree , I have make a satellite antenna receiver on motion by monopulse system , but I road in monopulse many use diplexer I don!t know how to do !?

    I have to make 180 degree 4 pcs for 950 MHz to 2700mhz to give the if signal from lnb to it than I put signal after hybrid to servo to track satellite on my car , I made all in my home , can advice and help to give me more info about it

    • Hi. Sorry I thought your question was related to coupling matrices. If I understand you correctly your hybrid goes after your LNB and it is therefore not critical that your hybrid is lossy? What is it that you are feeding with your hybrid? In that case you have lots of options to implement your broadband hybrid. Since it’s relatively low frequency the easiest would be to use a transformer (wire wound) based balun. They are broadband and has excellent balance. You can search at for parts, just search for broadband balun OR if you want to do it on your own you could wind one yourself 🙂 just make sure which impedance ratio you need. If you have space on your pcb you could also implement it as a planar circuit. Search for branch-line coupler, wilkinson hybrid or rat race. You would probably have to go for a multi-section design due to the multi-octave bandwidth!

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