[CQ-Contest] Is HF HF propagation reciprocal?

[k3bu at optonline.net]

>>For years, it has been theorized that one way skip is caused 
> by a tilt
> > of the ionosphere, so that signals going in one direction 
> strike it at
> > a very shallow angle, whereas signals coming the other way 
> strike it
> > at a more acute angle. Due to the angle of incidence vs MUF, one
> > signal will be reflected and the other will not.
> >
> > I don't know if this has ever been convincingly proven or not, 
> but it
> > sounds reasonable. Does anyone have any further information?
> >
> > Bill W6WRT
> >

I described my observations and possible explanation in my CQ article
http://www.k3bu.us/propagation.htm

Yuri, K3BU, VE3BMV