What does G/T represent in SATCOM theory?

• A. It is the product of antenna gain and system temperature.
• B. It is the ratio of transmitter power to system temperature.
• C. It is the ratio of antenna gain to system noise temperature.
• D. It is the ratio of downlink bandwidth to noise temperature.

Answer: (C)

G/T is the receiver sensitivity metric used in SATCOM. It represents how well the receiving chain can pick up weak signals, and it is defined as the antenna gain divided by the system noise temperature. In practice, you compare how much signal the antenna can collect (gain) to how much noise is present in the system (noise temperature). A higher G/T means you can detect weaker signals, which improves link performance and margin. Gain boosts the desired signal at the receiver input, while a lower noise temperature reduces the noise floor. Expressed in dB/K, it’s commonly calculated as G(dBi) minus 10 log10(Tsys in Kelvin). The other options mix different quantities that don’t describe the receiver’s sensitivity in the same way.