Enter the diameter of the antenna and the wavelength of the radio wave into the calculator to determine the far-field distance.

Far-Field Formula

The following formula is used to calculate a far field. 

dF = 2 * D^2 / λ
  • Where dF is the far field distance
  • D is the diameter of the antenna
  • λ is the wavelength of the radio wave

To calculate the far field, multiply the diameter of the antenna squared by 2, then divide by the wavelength of the radio wave.

What is a far-field?

Definition:

Far field is a term used in electromagnetism to describe one of the regions around an antenna where the far field is the dominating behavior.

How to calculate far-field?

Example Problem:

The following example outlines the steps required to calculate the distance of a far field.

First, determine the diameter of the antenna. For this example, the diameter is measured to be .15 m.

Next, determine the wavelength of the radio wave. In this case, the wavelength is 10m.

Finally, calculate the far field distance using the formula above:

dF = 2 * D^2 / λ

dF = 2 * .15^2 / 15

dF = .003 m