Antenna Noise

Receiver antenna detects not only radio waves but alo various noises.

The examples of the noise are:

  • Galactic noise
  • Solar noise
  • Noise radiated by clouds and rain
  • Atmospheric noise

Noise temperature received by the antenna \(T_a\) is:

\[T_a = T_s + (1-\eta)T_0\]

where \(T_s\) is the noise temperature, \(T_0\) is the ambient temperature, and \(\eta\) is the radiation efficiency of the antenna.