- Aug 25, 2014
There is no such thing as a "totally flat surface", even at sea. At 990 miles, the curvature of the earth comes into play. Broadcast signals in the TV bands travel in straight lines. They do not follow the curvature of the earth. At 990 miles, those signals could only be received at 620,000 feet in the air (619,120.4 feet to be exact) because the earth has "curved away" from the straight line path of those signals. Don't believe me? Click here to see the actual calculation....but on a high enough antenna mount (say 250 foot) with a totally flat surface (such as a calm sea) you might get reception at 990 miles...
This is why this "990 miles" specification is so ridiculous. It is electronically and physically impossible for ANY antenna to pick up signals on the TV band that originate from 990 miles away, even if it is 250 feet in the air.