Title: Relation between Power density and temperature in an antenna Date: 2008-03-28 18:29 Author: Andrea Zonca Tags: astrophysics, physics Slug: relation-between-power-density-and
Considering an antenna placed inside a blackbody enclosure at temperature T, the power received per unit bandwidth is:
where k is Boltzmann constant.
This relationship derives from considering a constant brightness
Power per unit bandwidth is obtained by integrating brightness over antenna beam
therefore
where:
-
$latex A_e$ is antenna effective aperture -
$latex \Omega_A$ is antenna beam area
$latex \lambda^2 = A_e\Omega_A $ another post should talk about this
finally:
$latex \omega = kT $
which is the same noise power of a resistor.
source : Kraus Radio Astronomy pag 107