So the GHz bands are "line of sight" only, eh?

Today, I had a 10GHz QSO with G4HTZ, down near the Essex Coast. We both run similar systems, a few Watts to a Sky dish. Both of us are a few metres above sea level, and the path between us is about as far from "Line of sight" as you can get (see plot) at around 88km.
Signals were 55 both ways on SSB with deep rapid Flutter QSB.
    

When we switched to NBFM, signals sounded like I was working a 70cm mobile station travelling at speed but perfect copy.
The propagation mechanism was clearly Tropospheric Scatter, and the loss calculations from Dr Mike, G0MJW's excellent path calculator confirm this (see plot). By comparison, signals on 144MHz would have been quite difficult, without running a BIG system. Add that to the horrendous noise levels these days on 144MHz, trying to use VHF talkback would have been difficult to say the least. Of course the key to all this, and why 10GHz is so effective over this range is the EIRP involved. Sky dishes have upwards of 25dB gain on 10GHz giving 3 kilowatts of ERP for a 10 Watts in. 

Don't just use 10GHz once a month in the UKACs or go out /P once a year! Get on the bands at other times! You might make some interesting QSOs.