LUF higher than MUF

Discussion in 'General Technical Questions and Answers' started by AL4Y, Oct 24, 2018.

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  1. AL4Y

    AL4Y Ham Member QRZ Page

    What does it mean when the predicted LUF is higher than the predicted MUF? Below is a snippet from the ARRL’s propagation chart for October 2018.
    upload_2018-10-23_21-4-56.png Charts/10akhi70.pdf
    For a good part of the day the LUF (blue) is higher than both the MUF (green) and the HPF (red). I am guessing that means that there is no usable frequency during that time frame due to D layer absorption, but someone more learned please break it down for me.
  2. K6CLS

    K6CLS Ham Member QRZ Page

    you have to use "snow bounce". get the dogs to do laps around the property with the snow blower pointing up, then zap the crap with your 1kW microwave signal.

    (just kidding!)
    K0OKS likes this.
  3. N3HGB

    N3HGB Ham Member QRZ Page

    You can't there from here?
    KK5JY likes this.
  4. KK5JY

    KK5JY Ham Member QRZ Page

    "Alaska to Western Europe" is a challenge, even when the sun is covered with spots. If you look at the great circle path, it's not hard to imagine why that is. In the years where SF is low (like now), there's going to be a big chunk of the day where the ionosphere just can't do that path, on any frequency.

    "Oklahoma to India" looks a lot like that, too. :)
  5. AL4Y

    AL4Y Ham Member QRZ Page

    Right, but Oklahoma to India is 15,000 km. Alaska to Western Europe is more like 5,000 km, similar to the distance between Alaska and Oklahoma.
  6. KK5JY

    KK5JY Ham Member QRZ Page

    The distance is different, but the "over the pole" problem still exists. That path does a great job of obliterating the MUF.
  7. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    This is the case in Interior Alaska MOST of the time. They don't call us the Bermuda Triangle of RF for nothing!
  8. K0RGR

    K0RGR Premium Subscriber QRZ Page

    I think you've got that right, and it's not that unusual this time of year here in the more northern latitudes.

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