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An Observation.

An Observation from Norway.

2m and 70cm knife-edge propagation is a well known phenomenon for those that 
live in mountainous areas.

Theoretically, from my QTH on Frei Island I shouldn't be able to work North 
America on a low earth orbit satellite due to the proximity of the extreemly 
high mountains from N.N.W. of my antenna array to S.S.E. and since antipodal 
propagation is not as common this far north as it is nearer the equator the 
chances of satellite DX on a LEO are minimal ... though almost permanent 
auroral propagation makes life interesting via satellite ... remember, the 
signal traverses the ionoshere twice!.

That being said, by careful monitoring of a tracking program it is possible 
to find an AO-7 orbit where knife-edged propagation could be used to "sneak" 
around the edge of the mountains.

Bearing in mind an average 2 x 6 array has less than the more common 3dB 
half power point the "aiming" has to be fairly accurate. For the newcomer 
this means that only half of the uplink power will actually manage to scrape 
around the mountain ... (reflection and refraction also has to be taken into 
account, likewise eventual ground gain) ... therefore, there are a lot of 
variable to contend with ... not least the idiosyncracies of the ionosphere 
as well as the polarisation of the signal.

However, being an AO-7 afficiondo I've been trying for quite some time to 
defeat these mountains and get into the States while working AO-7.

Imagine my surprise therefore when after repeated CQ's I finally heard 

I used to work the States daily on AO-13 but a relative LEO like AO-7 is a 
different matter from this particular QTH on Frei Island. JP33WB.

The moral of the story? ... don't give up, give it a try, you never know.

It was well worth the effort.

Good 'un! Ron mate!.

73 John.   <la2qaa@amsat.org>
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