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words, antenna noise temperature is a parameter that describes how much noise an antenna produces in a given environment. This temperature is not the physical temperature of the antenna. Moreover, an antenna does not have an intrinsic "antenna temperature" associated with it; rather the temperature depends on its gain pattern, pointing direction, and the thermal environment that it is placed in.
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of an antenna is a measure of the noise power density contributed by the antenna to the overall RF receiver system. It is defined as "the temperature of a resistor having an available thermal noise power per unit bandwidth equal to that at the antenna's output at a specified frequency". In other
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to all noise sources in its environment as well as on noise generated within the antenna. That is, in a directional antenna, the portion of the noise source that the antenna's main and side lobes intersect contribute proportionally.
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For example, a satellite antenna may not receive noise contribution from the Earth in its main lobe, but sidelobes will contribute a portion of the 288 K Earth noise to its overall noise temperature.
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Galactic noise is high below 1000 MHz. At around 150 MHz, it is approximately 1000 K. At 2500 MHz, it has leveled off to around 10 K.
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Antenna noise is only one of the contributors to the overall noise temperature of an RF receiver system, so it is typically subscripted, such as
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234:{\displaystyle T={\frac {P_{\text{noise}}}{kB}}={\frac {1}{k}}{\frac {P_{\text{noise}}}{B}}}
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163:(IF) filter of the radio receiver. Thus, we can define the noise temperature as:
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The level of the Sun's contribution depends on the solar flux. It is given by
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IEEE Std 145-2013, IEEE Standard for
Definitions of Terms for Antennas, IEEE
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Antenna noise temperature has contributions from many sources, including:
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as noise power spectral density (with unit W/Hz) normalized by
445:{\displaystyle T_{\text{A}}=3.468\,F{{\lambda }^{2}}10^{G/10}}
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595:(Third ed.). Boston: McGraw-Hill. pp. 731–732.
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Earth has an accepted standard temperature of 288 K.
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is the logarithmic gain of the antenna in decibels.
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617:. Newington: American Radio Relay League. 1990.
323:{\displaystyle T_{S}=T_{\text{A}}+T_{\text{E}}}
89:In radio frequency (RF) applications such as
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615:The Arrl Uhf/Microwave Experimenter's Manual
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77:Learn how and when to remove this message
40:This article includes a list of general
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270:of the receiver to obtain the overall
159:is determined by the bandwidth of the
343:Cosmic microwave background radiation
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118:is defined using the relationship
46:it lacks sufficient corresponding
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266:. It is added directly to the
633:"ITU P.372 : Radio noise"
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593:Introduction to Radar Systems
591:Skolnik, Merrill I. (2001).
268:effective noise temperature
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18:Antenna noise temperature
491:{\displaystyle \lambda }
334:Sources of antenna noise
272:system noise temperature
61:more precise citations.
558:Federal Standard 1037C
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370:The antenna itself
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548:Noise Temperature
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515:{\displaystyle G}
468:{\displaystyle F}
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637:. Retrieved
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67:January 2013
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657:Temperature
563:MIL-STD-188
116:noise power
110:Mathematics
59:introducing
651:Categories
569:References
42:references
486:λ
414:λ
542:See also
531:coupling
244:Because
131:, where
151:is the
143:is the
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55:improve
639:4 July
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455:where
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44:, but
635:. ITU
404:3.468
222:noise
187:noise
124:noise
95:radar
91:radio
641:2019
619:ISBN
597:ISBN
502:and
363:Moon
361:The
355:The
97:and
357:Sun
128:kTB
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254:k
250:T
246:k
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210:k
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193:k
183:P
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174:T
149:B
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133:k
121:P
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