Observations From Norway  07_06_2008

The case for polarisation switching.

As some of you may know, I work Sergey in Kamchatskaya (6800km) every weekend on AO-7 so "know" his signal.  As I have mentioned previously, like me, due to the mountains, he too, frequently uses knife-edge propagation as a "mode" on LEO's.

As you are of course aware, the polarisation of an electrical wave changes when 'reflected'.  This has to be taken into account when using knife-edge polarisation/reflection/refraction as a means to communicate via satellite (AO-7).

This morning, just to confirm that which I usually 'gob' about, I was 'active' with my polarisation switch. The difference in Sergey's signal was 'dramatic' with the signal strength varying between fully workable and totally unreadable.

Obviously, there are a few other parameters in the equation, propagation anomalies and what have you - but there's no question that the case for switchable polarisation on *LEO*'s is without a shadow of a doubt a distinct advantage when working more than 'spitting' distance.

73 John.   <la2qaa@amsat.org>
 

Footnote by Al GM1SXX.     John uses a very modest aerial setup consisting of a commercially made 2M CP (switchable) Wimo antenna and a pair of DIY yagis for 70Cms. Both aerials have polarisation switching, a necessity when working QRP satellite by knife-edge scatter mode. Some radio amateurs would consider operating via the ailing QRP only satellite AO7 to be a challenge. 

Using knife-edge propagation from a site bounded by sizeable mountains to communicate over 6800Kms via a QRP only satellite is a real challenge.