posted on Sep, 11 2014 @ 01:52 PM
a reply to: Nettlas
It depends on the system, the topography and the local regulations which in times of heightened tension may be lifted.
Typically a Naval radar system which spot's ships or even a civil maritime system is down to a few feet with wave's causing the main interference
and that is the point a radar system is looking for return signals and waves at sea cause sporadic returns that can cause interferrance, a real
problem for human operators but no so much for computerised systems that can process the bulk of that data and look for regular sustained returns, so
in that case 1 to six feet is the probably basement of the system.
On land a whole other range of problems occure and topography, construction limit the range of military radar at lower altitude's and other natural
deviation in the natural horizon also limit that lowest altitude, this is why the old Tomohawk cruise missiles which was designed to exploit this
weakness used a down facing topographic radar to navigate an internal satelite obtained topographical map to there target, even if they were detected
they would be lost just as quickly as they followed natural ravines etc to there target.
Typically though civil aviation radar has a much higher starting altitude
During WW2 both sides tried to exploit this weakness in there adversaries radar systems and after the war the new antagonists of the east and west
tried to developt this flaw out of there systems, military radar really is a different beast to civil radar and that is why.