The noise level, seen by the receiver, seems relativly constant in my experience as in the recever is seeing general background noise with probably widespread particular geographical sources. So in a city for instance where you point a directional antenna may make no difference to the level of noise seen.
Easy test to carry out, if you had access to the great outdoors, my guess is that there will be little to no difference.
In any case you would be implementing a Gateway with very restricted coverage.