6m Aircraft Scatter

My last blog entry covered an experiment to prove that it is possible to get a straight line reflection from an Aircraft travelling away from both the originating, TX, station and the receiving station.

The Aircraft needs to be, I believe on the same bearing as that of the path between the two stations.

At my QTH this is merely a waiting game, there are so many aircraft on the S/N corridor that finally one will fit the equation.

Previous tests with G6AVK did not achieve the desired result. I think that, while his omni directional signal reached me fine, by the time it got to Aircraft sufficiently North of me it had run out of ‘steam’.
The addition at G6AVK of a mast and rotatable 6m Beam means that strong Aircraft reflections from the North are now possible.

I pointed my beam in line with the S/N UK Air Corridor G6AVK beamed toward me.
Note the trace at 19.32. There is the direct signal from AVK. A long descending trace from an Aircraft, which has passed me and is heading North, on a track at a tangent to the path between AVK and ZJO. Third a parallel trace, ‘classic’ 61Hz shift equating to an air speed of c.600Km Hour.

This produced 2 decodes of WSPR on the two frequencies.

2009-05-29 19:32 G6AVK 50.294482 -18 1 JO01ho 5 G3ZJO IO92ng 127 306
2009-05-29 19:32 G6AVK 50.294421 -25 0 JO01ho 5 G3ZJO IO92ng 127 306

I think we can now say that this is the definitive explanation of the phenomena. Repeatable by experiment, using 3 different signal sources.


6 thoughts on “6m Aircraft Scatter

  1. Fascinating stuff. I was trying some similar experiments last week in the Perseids on 10m WSPR. There were some whispy watery traces which could have been MS or indeed aircraft reflections.

    Isn’t WSPR just amazing!


  2. Hi Roger

    Yes WSPR with its narrow bandwidth has drawn attention to small shifts be they from Doppler or poor thermal stability in rigs. Indeed when we first ventured on to 6m WSPR ‘bannana’ signals were reported far too often. This lead me to investigate A/S on the band.


  3. Hi Eddie,

    I came across your blog after reading a link about aircraft scatter on 10GHz.

    A fascinating experiment, great to see you are still active and that there is real amateur radio going on beyond the use of repeaters!

    If you ever fancy a chat on HF, I’m now a reasonable signal into the UK from Brisbane. I spend quite some time on the microwave bands, and meteor scatter. I’ve also built the Genesis SDR transceiver for 160m – 6m.

    Keep up the good work Eddie…

    Phil VK4IIO – G4IIO


  4. Hi Phil

    Nice to hear from you. I recently blogged OPERA Mode A/S on 50 MHz based on what we have learned. Its now like clay pigeon shooting, G6AVK and I can both beam to hot spots I predict such as the Irish Sea past Fishguard and in come straight decoded reflections from aircraft once they reach the right criteria (approaching or receding from both stations equally).
    Yes still very busy building /experimenting here, I rarely use a Mic these days good to hear about the Genesis.
    Yes I will have to try a contact some time, when are you about.


    1. Long path in the mornings UK time around 08:00, if you have Skype we can hook up there for a frequency at the weekends.

      My Skype address is philg4iio



  5. OK Phil, we Skype Melbourne regularly now, Son / Daughter in law are down there.

    Have you noted the 8.9kHz experiments, this weekend we have PA, DL, OE and OK signals coming in on my E-Probe – 30mm long 🙂


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