Topband: Fwd: Echo on 160m yesterday morning

[K1FZ-Bruce]

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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