Antenna Field regions calculator

Field regions.

Frequency:	f =		Hz
Maximum dimension of the antenna:	d =		m
Reactive region radius:	r1 =		m
Radiating region radius:	r2 =		m

The space surrounding an antenna is usually subdivided into three regions: the reactive near-field, the radiating near-field (Fresnell) and the far-field (Fraunhofer) regions. These regions are so designed to identify the field structure in each, but no abrupt changes in the field configurations are noted.

Reactive near-field region:	That portion of the near-field region immediately surrounding the antenna wherein the reactive field predominates.
Radiating near-field (Fresnel) region:	That region of the field of an antenna between the reactive near-field region and the far-field region wherein radiation fields predominate and wherein the angular field distribution is dependent upon the distance from the antenna.
Far-field (Fraunhofer) region:	That region of the field of an antenna where the angular field distribution is essentially independent of the distance from the antenna.

Bibliography:

C.-A. Balanis, Antenna theory, analysis and design Wiley, 1997, Chapter 2.