"larry" wrote:

The point is that once you have gotten away from the earths curvature,
power
on vhf and uhf has almost little meaning.

That's not quite true. Yes, earth curvature is the big limiting factor for
terrestrial communications.

But in free space, signal strength decreases as an "inverse square" function
with distance. Everytime you double the distance between the transmitter and
receiver, the signal strength decreases by 6 dB (i.e., it becomes only 1/4
as strong). Think of shining a flashlight on a wall. As you move the
flashlight further away, it illuminates a larger area, but the intensity
decreases.

Yes, low power can cover great distances in free space. But power is not is
not meaningless. If it were, you wouldn't need those big dishes for C-Band
satellite reception.

Free space path loss equation:

Path Loss (dB) = 36.6 + 20 Log F + 20 Log D

Where F is frequency in MHz, and D is distance in miles. (Assumes isotropic
antennas at each end, 0 dBi gain).

Art Harris N2AH