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This parameter is written as G/T, and has units of dB·K −1. G/T Calculation. G/T is the figure of merit for a satellite system. G is the Receive antenna gain. T is the system noise temperature. System noise temperature = antenna noise temperature + Receiver noise temperature (LNA)
dB K dB(K) – decibels relative to 1 K; used to express noise temperature. [67] dB K⁻¹ or dB /K dB(K⁻¹) – decibels relative to 1 K⁻¹. [68] — not decibels per Kelvin: Used for the G / T (G/T) factor, a figure of merit used in satellite communications, relating the antenna gain G to the receiver system noise equivalent ...
For instance, if stage 1 represents a 6 dB attenuator so that =, then = + +. Effectively the noise temperature of the amplifier T 2 {\displaystyle T_{2}} has been quadrupled, in addition to the (smaller) contribution due to the attenuator itself T 1 {\displaystyle T_{1}} (usually room temperature if the attenuator is composed of resistors ).
Here, k ≈ 1.38 × 10 −23 J/K is the Boltzmann constant and kT 0 is the available noise power density (the noise is thermal noise, Johnson noise). As a numerical example: A receiver has a bandwidth of 100 MHz, a noise figure of 1.5 dB and the physical temperature of the system is 290 K.
They pass both quadratures. For an optical amplifier it holds F o,IQ = n sp (1-1/G)+1/G ≥ 1. Quantity n sp (1-1/G) is the input-referred number of added noise photons per mode. F o,IQ and F pnf can easily be converted into each other. For large G it holds F o,IQ = F pnf /2 or, when expressed in dB, F o,IQ is 3 dB less than F pnf. The ideal F ...
From the gain factor G, one finds the gain in decibels as: G dBi = 10 log 10 ( G ) . {\displaystyle G_{\text{dBi}}=10\log _{10}\left(G\right).} Therefore, an antenna with a peak power gain of 5 would be said to have a gain of 7 dBi. dBi is used rather than just dB to emphasize that this is the gain according to the basic definition, in ...
The Deep Space Network has been able to maintain the link at a higher than expected bitrate through a series of improvements, such as increasing the antenna size from 64 m to 70 m for a 1.2 dB gain, and upgrading to low noise electronics for a 0.5 dB gain in 2000–2001.
Friis' original idea behind his transmission formula was to dispense with the usage of directivity or gain when describing antenna performance. In their place is the descriptor of antenna capture area as one of two important parts of the transmission formula that characterizes the behavior of a free-space radio circuit.