Free space path loss
Calculate the free-space path loss (in dB) of a 10 GHz radar signal over a distance of 10 km.
fc = 10.0e9; lambda = physconst('LightSpeed')/fc; R = 10e3; L = fspl(R,lambda)
L = 132.4478
R— Propagation distance of signal
Units are in meters.
lambda— Speed of propagation divided by the signal frequency
Wavelength units are meters.
The free-space path loss, L, in decibels is:
This formula assumes that the target is in the far-field of the transmitting element or array. In the near-field, the free-space path loss formula is not valid and can result in a loss smaller than 0 dB, equivalent to a signal gain. For this reason, the loss is set to 0 dB for range values R ≤ λ/4π.
 Proakis, J. Digital Communications. New York: McGraw-Hill, 2001.
Usage notes and limitations:
Does not support variable-size inputs.