Download IEEE Std 145'-2013 PDF

TitleIEEE Std 145'-2013
LanguageEnglish
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IEEE Standard for Definitions of Terms
for Antennas


Sponsored by the

Antennas Committee



IEEE
3 Park Avenue
New York, NY 10016-5997
USA


IEEE Antennas and Propagation Society

IEEE Std 145™-2013
(Revision of

IEEE Std 145-1993)


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Fresnel lens antenna: An antenna consisting of a feed and a lens (usually planar) that

transmits the radiated power from the feed through the central zone and alternate Fresnel zones of

the illuminating field on the lens. Syn: zone-plate lens antenna.



Fresnel pattern: A radiation pattern obtained in the Fresnel region.



Fresnel region: The region (or regions) adjacent to the region in which the field of an antenna is

focused (that is, just outside the Fraunhofer region).



NOTE 1—In the Fresnel region in space, the values of the fields when calculated from

knowledge of the source distribution of an antenna are insufficiently accurate unless the quadratic

phase terms are taken into account, but are sufficiently accurate if the quadratic phase terms are

included.



NOTE 2—See: NOTE 2 of near-field region, radiating for a more-restricted usage.



Fresnel zone: The region on a surface between successive Fresnel contours.



NOTE—Fresnel zones are usually numbered consecutively, with the first zone containing the

minimum path length.



front-to-back ratio: The ratio of the maximum directivity of an antenna to its directivity in a

specified rearward direction.



NOTE 1—This definition is usually applied to beam-type patterns.



NOTE 2—If the rearward direction is not specified, it shall be is taken to be that of the maximum

directivity in the rearward hemi sphere relative to the antenna’s orientation.





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gain: See: gain, partial (of an antenna for a given polarization); realized gain; realized gain, partial

(of an antenna for a given polarization).



gain (in a given direction): The ratio of the radiation intensity, in a given direction, to the

radiation intensity that would be obtained produced if the power accepted by the antenna were

isotropically radiated. Syn: absolute gain (of an antenna).



NOTE 1—Gain does not include losses arising from impedance and polarization mismatches and

does not depend on the system to which the antenna is connected.



NOTE 2—The radiation intensity corresponding to the isotropically radiated power is equal to the

power accepted by the antenna divided by 4π.



NOTE 3—If an antenna is without dissipative loss, then in any given direction, its gain is equal to its

directivity.



NOTE 4—If the direction is not specified, the direction of maximum radiation intensity is implied.



NOTE 5—The term absolute gain is used in those instances where added emphasis is required to

distinguish gain from relative gain: for example, absolute gain measurements.



gain, partial (of an antenna for a given polarization): In a given direction, that part of the

radiation intensity corresponding to a given polarization divided by the radiation intensity that

would be obtained if the power accepted by the antenna were isotropically radiated.



NOTE—The (total) gain of an antenna in a specified direction is the sum of the partial gains for any

two orthogonal polarizations.



geodesic lens antenna: A lens antenna having a two-dimensional lens with uniform index of

refraction, disposed on a surface such that the rays in the lens follow geodesic (minimal) paths of the

surface.

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wideband antenna. See: broadband antenna.



wire antenna: An antenna composed of one or more conductors, each of which is long compared to

the transverse dimensions, and with transverse dimensions of each conductor so small compared to

a wavelength that for the purpose of computation the current can be assumed to flow entirely

longitudinally and to have negligible circumferential variation.



wire-grid lens antenna: A lens antenna constructed of wire grids in which the effective index of

refraction (and thus the path delay) is locally controlled by the dimensions and the spacings of the

wire grid. Contrast with: geodesic lens antenna; Luneberg lens antenna.



Wullenweber antenna: An antenna consisting of a circular array of radiating elements, each

havinghas its maximum directivity along the outward radial, and a feed system that provides a

steerable beam that is narrow in the azimuth plane.



Yagi antenna: [Deprecated.] See: Yagi-Uda antenna.



Yagi-Uda antenna: A linear end-fire wire antenna array consisting of a driven element, a

reflector element, and one or more director elements.



zoned antenna: A lens or reflector antenna having various portions (called zones or steps) that form

a discontinuous surface such that a desired phase distribution of the aperture illumination is

achieved. Syn: stepped antenna.



zone-plate lens antenna: See: Fresnel lens antenna.

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