WordNet
n. graphical representation (in polar or cartesian coordinates) of the spatial distribution of radiation from an antenna as a function of angle [syn: radiation diagram, pattern]
Wikipedia
thumb|right|upright=1.4|Three-dimensional antenna radiation patterns. The radial distance from the origin in any direction represents the strength of radiation emitted in that direction. The top shows the directive pattern of a horn antenna, the bottom shows the omnidirectional pattern of a simple vertical antenna.
In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the directional (angular) dependence of the strength of the radio waves from the antenna or other source.
Particularly in the fields of fiber optics, lasers, and integrated optics, the term radiation pattern may also be used as a synonym for the near-field pattern or Fresnel pattern. This refers to the positional dependence of the electromagnetic field in the near-field, or Fresnel region of the source. The near-field pattern is most commonly defined over a plane placed in front of the source, or over a cylindrical or spherical surface enclosing it.
The far-field pattern of an antenna may be determined experimentally at an antenna range, or alternatively, the near-field pattern may be found using a near-field scanner, and the radiation pattern deduced from it by computation. The far-field radiation pattern can also be calculated from the antenna shape by computer programs such as NEC. Other software, like HFSS can also compute the near field.
The far field radiation pattern may be represented graphically as a plot of one of a number of related variables, including; the field strength at a constant (large) radius (an amplitude pattern or field pattern), the power per unit solid angle (power pattern) and the directive gain. Very often, only the relative amplitude is plotted, normalized either to the amplitude on the antenna boresight, or to the total radiated power. The plotted quantity may be shown on a linear scale, or in dB. The plot is typically represented as a three-dimensional graph (as at right), or as separate graphs in the vertical plane and horizontal plane. This is often known as a polar diagram.
Usage examples of "radiation pattern".
Prilida had reported a steady radiation pattern of confusion, anxiety and helplessness.
The Ergometer on the Shooting Starr could pick up the radiation pattern of a hyperatomic motor on ships no larger than an ordinary lifeboat and do it at a distance of better than two million miles.
Like, a civilian broadcasting system tries to get a wide radiation pattern.
Given a few days, some shielding -- there's an odd radiation pattern from that wall behind you -- and projection dampers, I might, I just might achieve a fair degree of accuracy.
Those screens are apparently designed not only to protect the ship but to modify its radiation pattern in such a way that its true surface temperature is not readily apparent through observations made in the standard electromagnetic spectrum.