Friis Transmission Equation Calculator

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The Friis transmission equation, as shown below, gives the ratio of received to transmitted power for given antenna gains, range and wavelength under ideal conditions. The calculator below uses this equation to calculate any one of the variables, provided all the other variables are known.

Friis Transmission Equation

Enter the known values in any one of the available units, then click on the Calculate button next to the value you wish to calculate.

Transmit Power, Pt  W  
Transmit Antenna Gain, Gt  dBi  
Receiver Antenna Gain, Gr  dBi  
Received Power, Pr  W  
Range, meters  
Frequency kHz  
Wavelength, λ  meters  

Effective Isotropic Radiated Power, EIRP
 Power Density at Receiver, PD
Electric Field Strength at Receiver, E Assuming
free space
Magnetic Field Strength at Receiver, H
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Whilst I try to keep the information on this site accurate, I'm only human and I do occasionally make mistakes. I therefore advise you to check any information before using it for anything important. If you do find any errors, please let me know so that I can correct them.

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This page was last changed on: 02 August 2021.

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