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.