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custom microstrip resonator

Discussion in 'Electronic Design' started by Kubicki, Sep 12, 2003.

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  1. Kubicki

    Kubicki Guest

    Hi all,
    I'm looking for a microstrip resonator (i.e. lambda/2) for circuit assembly.
    Does anybody know where I can find something like that or someone that would
    be able to build it?
    The application require a resonant frequency of 2.5GHz and a Q factor of
    200.

    Thanks to all.

    Alle.
     
  2. Don Pearce

    Don Pearce Guest

    You won't achieve a Q of 200 in microstrip. A tuned cavity would be
    the solution here. Loose probe coupling into an air-spaced coaxial
    chamber with a half wave inner will do it.

    If you do decide to try microstrip, then you simply etch or scrape and
    peel a piece of PC board to the appropriate length - nothing to buy.

    d

    _____________________________

    http://www.pearce.uk.com
     
  3. John Larkin

    John Larkin Guest

    You might consider a coaxial ceramic resonator; they have Qs in the
    thousands and are very stable.

    John
     
  4. Kubicki

    Kubicki Guest

    You won't achieve a Q of 200 in microstrip. A tuned cavity would be
    Thank you Don!
    I need to place it into a PCB, and so I would ask you what are approximately
    the dimensions of this cavity.

    I need to do a Frequency-Voltage converter in the range of 2.5GHz and so my
    application require two resonators with similar but not equal resonant
    frequencies, with a difference of, say, 20MHz (something that look like old
    FM demodulators).

    In your opinion, is this slight difference achievable with resonant
    cavities?

    Thank you.

    A.
     
  5. Don Pearce

    Don Pearce Guest

    First, to do this job you only need a single resonator. Look at the
    way most FM tuner ICs work to see how to use it. The resonator need
    only be a quarter wavelength. At 2.5GHz that is about 3cm in air. This
    would be the case for a cavity. If you can get, as suggested, a
    ceramic resonator, then it will be much smaller.

    Alternative;y, you can downconvert the frequency so that the
    percentage change is much greater.

    d

    _____________________________

    http://www.pearce.uk.com
     
  6. Andrew Paule

    Andrew Paule Guest

    You can make your own resonators in a board by cutting a "notch" in the
    ground plane (ask me - works like a charm, especially when you don't
    want it - learn from your mistakes - I try to, but.....). VERY high Q
    (> 200), really cool when you're not expecting it - I' buy off shelf
    cavitys - tuning is better and they work when they are expected to.
    Andrew
     
  7. Andrew Paule wrote...
    Talk us through a typical notch in the ground plane resonator.
    Frequency vs size of notch, a more detailed description, etc.

    Thanks,
    - Win
     
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