What is the significance of G/T ratio?


24. What is the significance of G/T ratio?

Useful figure of merit for receive antennas is the G/T ratio, defined as 10 log( G/ TA) dB/K, where G is the gain of the antenna, and TA is the antenna noise temperature.

This quantity is important because, the signal-to-noise ratio (SNR) at the input to a receiver is proportional to G/TA. The ratio G/T can often be maximized by increasing the gain of the antenna, since this increases the numerator and usually minimizes reception of noise from hot sources at low elevation angles. Of course, higher gain requires a larger and more expensive antenna, and high gain may not be desirable for applications requiring omnidirectional coverage (e.g., cellular telephones or mobile data networks), so often a compromise must be made.

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