Isotropic losses of free-space radiation.

Picture showing a transmittin antenna and a receiving one

a_iso = ((4 pi d) / lambda)^2
Frequency:f = Hz
Distance:d = m
Path loss:Aiso = dB

Enter the frequency f and one value (either d or Aiso) and click the "Calculate" button next to it to compute the other one.

These values are only valid for far-field radiation. Antennas have to be perfectly aligned and with the same polarization. The space between the two antennas has to be free.
Only the geometrical loss is considered; absorption in the air or other materials are not taken into account.

Bibliography:

P.-G. Fontolliet, Traité d'Électricité, Vol. XVIII: Systèmes de télécommunications Presses Polytechniques et Universitaires Romandes, 1996, p. 416.

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