"nobody" wrote in message ...
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?

You have reached the wrong conclusion about the distance 100 mw can reach.
That distance is just one persons expirment and also over earth and not
direct line of sight. Also the type of equipment used is not very well
designed for maximum distance. There is no real set distance that a given
ammount of power can reach. It also depends on the antennas and receiver
and several other factors. Knowing all factors involved the distance can be
estimated very close.