Free-space Path Loss - Free-space Path Loss Formula

Free-space Path Loss Formula

Free-space path loss is proportional to the square of the distance between the transmitter and receiver, and also proportional to the square of the frequency of the radio signal.

The equation for FSPL is

\begin{align} \mbox{FSPL} &= \left ( \frac{4\pi d}{\lambda} \right )^2 \\ &= \left ( \frac{4\pi d f}{c} \right )^2 \end{align}

where:

  • is the signal wavelength (in metres),
  • is the signal frequency (in hertz),
  • is the distance from the transmitter (in metres),
  • is the speed of light in a vacuum, 2.99792458 × 108 metres per second.

This equation is only accurate in the far field where spherical spreading can be assumed; it does not hold close to the transmitter.

Read more about this topic:  Free-space Path Loss

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