Free-space Path Loss (FSPL) is loss of signal strength on a line-of-sight path which has no obstacles or other disturbances. This equation uses the frequency and the distance from the transmitter to calculate the FSPL as decibels (dB).
This equation is only accurate at a distance from the transmitter where spherical spreading can be assumed. This equation is not accurate for short distances.
This equation, Free-Space Path Loss ( ), references 2 pages