Definitions
The term "near-field region" (also known as the "near-field" or "near-zone") has the following meanings with respect to different telecommunications technologies:
- The close-in region of an antenna where the angular field distribution is dependent upon the distance from the antenna.
- In the study of diffraction and antenna design, the near-field is that part of the radiated field that is below distances shorter than the Fresnel parameter S = D2/(4λ) from the source of the diffracting edge or antenna of longitude or diameter D.
- In optical fiber communications, the region close to a source or aperture.
Because of these nuances, special care must be taken when comprehending the literature about near-fields and far-fields.
Read more about this topic: Near And Far Field
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