Noise temperature is a measure of noise in electronic devices (or virtually anything that carries electricity), expressed as a temperature, as if the noise is thermal noise resulting from a device's temperature. Thermal noise is a primary cause of noise in electronics, and in that case, expressing it as the temperature is an obvious concept, but other sources of noise can be expressed as a temperature, allowing a means of comparison of noise contributors. Antenna temperature is an expression of antenna noise in such manner.
Noise temperature is defined as:
Tnoise = P / ( B kB )