Near and far field

Regions of an electromagnetic field

The near field and far field are regions of the electromagnetic (EM) field around an object, such as a transmitting antenna, or the result of radiation scattering off an object. Non-radiative near-field behaviors dominate close to the antenna or scatterer, while electromagnetic radiation far-field behaviors predominate at greater distances. Far-field E (electric) and B (magnetic) radiation field strengths decrease as the distance from the source increases, resulting in an inverse-square law for the power intensity of electromagnetic radiation in the transmitted signal.

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