Enter the transmitter gain, receiver gain, transmitted power, wavelength, and distance into the calculator to determine the received power using the Friis transmission equation. This calculator helps in understanding the power received by an antenna from another antenna under idealized conditions in free space.

Friis Transmission Equation

The Friis transmission equation is used to calculate the power received by an antenna from another antenna under idealized conditions in free space. The equation is as follows:

Pr = (Gt * Gr * λ^2 * Pt) / (16 * π^2 * d^2)

Variables:

  • Pr is the received power (watts)
  • Gt is the transmitter gain
  • Gr is the receiver gain
  • λ is the wavelength (meters)
  • Pt is the transmitted power (watts)
  • d is the distance between the antennas (meters)

To calculate the received power, input the transmitter gain, receiver gain, transmitted power, wavelength, and distance into the equation. The result will give you the power that is received by the antenna.

What is the Friis Transmission Equation?

The Friis transmission equation is a fundamental equation in the field of wireless communications, which relates the power received by an antenna to the power transmitted from another antenna, the gains of the antennas, the wavelength of the signal, and the distance between the antennas. It assumes a line-of-sight path without any interference from the environment.

How to Calculate Received Power Using the Friis Equation?

The following steps outline how to calculate the received power using the Friis transmission equation.

  1. First, determine the transmitter gain (Gt).
  2. Next, determine the receiver gain (Gr).
  3. Next, determine the transmitted power (Pt) in watts.
  4. Next, determine the wavelength (λ) in meters.
  5. Next, determine the distance (d) between the antennas in meters.
  6. Finally, calculate the received power (Pr) in watts using the Friis equation.
  7. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Transmitter Gain (Gt) = 2

Receiver Gain (Gr) = 3

Transmitted Power (Pt) = 100 watts

Wavelength (λ) = 0.5 meters

Distance (d) = 1000 meters