Free-space Loss

In satellite communications, free-space loss (or free-space path loss) is the major loss suffered by signals in traveling over the Earth-satellite path. The loss is inversely proportional to the square of the distance travelled and inversely proportional to the square of the frequency used. That is, as the distance is doubled the received power is reduced by a factor of four. Similarly, as the frequency is doubled the received power is reduced by a factor of four. Free-space loss for geostationary satellite communications satellites varies between 190–210 dB depending on the frequency used.