Total posts : 45366
Field intensity drops off with the square of the distance from the base of the antenna.
That is a commonly-written and accepted belief, but it applies to radiated power, not field intensity. And only in the far field.
Field intensity is a voltage, and it is inversely proportional to distance. The groundwave field at the end of a 200-meter path from the transmit antenna is half that of a 100-meter path, other things equal.