RF phase shift limiter

Discussion in 'Wireless & RF Design' started by lordofentropy, Mar 11, 2015.

  1. lordofentropy

    Thread Starter Active Member

    Apr 10, 2010
    I currently have a very narrow scope of RF and would like to remedy some of that. Right now my focus is in understanding specifically RF phase shift limiters, RF limiters in general, and then move into general RF amps all around applying it too RF signals 100 MHz or below, but focusing on signals in the 40 - 100 MHz range. I am having trouble finding specific information; so I was wondering if someone can help point me in the right direction.

  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    you will probably have to do the limiting at a low level in the modulation stage. the only rf limiters I am familiar with are the kind that reduce power when swr goes high, or problem detected, other rf limiters usually in earlier stages.
  3. Papabravo


    Feb 24, 2006
    Designing a circuit to absorb large amounts of RF power would be nonsensical in my estimation. Far better is the reduction in input drive to the final stage. This has the added benefit of being a linear process rather than a non-linear one. As for the detection mechanism to trigger the power reduction it can be anything you want. Temperature is a great indicator of component stress, so when the case gets too hot you limit the drive to the final. Simple, cheap, easy.

    When it comes to controlling phase shift, are you talking about oscillator phase noise or is this something else.
  4. BR-549

    Distinguished Member

    Sep 22, 2013
    It depends on what you mean by "RF phase shift limiter".

    Those words can mean different things in different fields of study.

    To me, your words would mean an IF chain in a commercial FM receiver.

    What do these words mean to you?
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
    the only high level rf phase shifter I can think of is a goniometer, a special set of coils used to adjust the output phase at broadcast stations to move the direction of the antenna radiation. on them, the phase limits are mechanical.