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  1. #1
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    how to make stripline

    How can I design a matching circuit using microstrip series stub on a PCB?

    I have been looking around and never understand what is a series stub. I understand design using smith chart, I just don't get the physical structure using stripline or microstrip.

    Thanks

    •   Alt14th June 2009, 07:26

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    microstrip series stub




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    stripline stubs

    Don't try to use a series stub matching network when working with microstrips. It is much easier to implement using shunt stubs instead. Physically it is just a piece of microstrip conductor at a 90° angle to the microstrip line.



    •   Alt15th June 2009, 14:56

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    series stub microstrip

    As YoungEng said is better shunt stub .
    Working frequency ?
    Bandwith ?
    Sustrate type ?



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    shunt stub implement

    Both ( series and shunt) are essential if BW requirement is more.



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    microwave stripline stub

    Simple series stubs are not possible in microstrip or stripline, as you can make a series structure in the top trace, but not in the ground plane underneath.

    Never the less, there are a number of series-like structures that can be used in stripline/microstrip. With some creativity, these can be included in matching structures. Look at Microwave Filters Impedance-Matching Networks, and Coupling Structures by Matthaei, Young, and Jones. On pages 219-228 there are a lot of depictions of such structures, although the models shown there are only accurate for TEM such as stripline, and not microstrip (which have εeven ≠εodd).

    Rich
    Last edited by keith1200rs; 1st May 2012 at 09:44. Reason: Advertising removed



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    stub series stripline

    You can do a lot with a series stub. With a 90degree phase shift at a given impedance you can transform to nearly any impedance.
    Here is a spreadsheet that will show you how to make them:
    http://www.microwaves101.com/downloads/Xfmr101Rev3.xls

    You can use it to make as many sections as you want. It only covers real impedances but you could tune it in your simulator for a complex match.[/url]

    The formula for a single 90 degree line is simple and as follows:
    ZT=(ZL*ZS)^0.5



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