Loss of power over distance (assuming no fresnel effect and nothing in the way). This a very idealised calculation and in practice everything interferes with the signal but it will give you a reasonable approximation of the actual loss over distance. Enter the system frequency in MHz and the distance in either Kilometers (Km) or Miles below and then click the 'Calculate' button.

1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.