I think this form of ducting takes place way above the layers of the atmosphere
where weather happens. In my experience the magnetospheric ducting is normally
localized in impact. If this was really happening in multiple places around the
world at the same time on this occasion then I think that is unusual.
Andy, G4PIQ
-----Original Message-----
From: "K1FZ-Bruce" <k1fz@myfairpoint.net>
Sent: 06/02/2017 13:46
To: "g4piq@btinternet.com" <g4piq@btinternet.com>; "Topband"
<topband@contesting.com>
Subject: Fwd: Echo on 160m yesterday morning
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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