Hi Andy,
Ducting takes place over a relatively small area. Depends upon cloud layers
and temperature zones
This event took place ~ world wide. Band openings between North America to
Asia, and Australia.
73
Bruce-k1fz
http://www.qsl.net/k1fz/beverage_antenna.html
On Mon, 6 Feb 2017 12:20:07 +0000 (GMT), Andy Cook wrote:
I think you'll find this was Magnetospheric Ducting. Take a look at some of the
articles here http://la3za.blogspot.co.uk/search/label/Unusual%20Propagation
and here http://folk.uio.no/sverre/papers/2009_MagnetoDucting-QST-LA3ZA.pdf.
Delay depends on your latitude - but couple of hundred millseconds is about
right and this is a peak time of year for the effect.
I've heard this quite frequently on 80m around mid local-evening during the
winter, and one occasion - on 3rd Feb last year - very strongly indeed. That
night I was able to hear my echoes with just 25mW into a dipole on 80m - but
it's often strong enough to be audible with a few watts. I've read papers which
suggested it does also occur on 160m.
Reports of these being less strong / gone when you switch to a vertical look
plausible as well since they apear to require vertical incidence from the
ionosphere.
73,
Andy, G4PIQ
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