sonnyyu:
Grumpy_Mike:
Every 6 dBi antenna gain will be double the distance.
Only in an ideal world, or line of sight. Not in practice.
People use it for cell phone reception of basement, subway, elevator... None of them are line of sight.
Again you have used up three posts to convey practically nothing, are you trying just to increase you post count?
Yes non of those examples are line of sight and in non of those examples does your simplistic rule apply.
Have you ever worked with radio?
Any radio ham will tell you that that rule only applies to line of sight where the transmission losses are due to isotropic radiation losses.