Fraunhofer distance

For other articles bearing the name of the physicist, see Fraunhofer.

The Fraunhofer distance, named after Joseph von Fraunhofer, is the value of:

${\displaystyle d={{2D^{2}} \over {\lambda }},}$

where D is the largest dimension of the radiator (in the case of a magnetic loop antenna, the diameter) and ${\displaystyle {\lambda }}$ is the wavelength of the radio wave. This distance provides the limit between the near and far field, allowing for 22.5 degrees of phase deviation over the face of the radiator.

See also

• Fresnel number
• Fresnel diffraction and Fraunhofer diffraction
• Antenna measurement