Total Power Radiometer

Hi dears,

I'd like to design an LNB that can be used for Total power radiometer by connect the LNB with square-law detector and low-pass filter in series. The radiometer will be used to detect hot spots "high temperature". I need your help to find a way to simulate like this system. My problem starts that how can I find a model to realize a thermal noise source and connect this model to the input of LNB.
If you have an example will be very helpful for me.

Thanks in Advance

Nothing is easier.
In other words: ask Yourself what really need.
E.g. the total power radiometer do not require a sophisticate simulator.
A very simple, cascade simulator, wrote in MS Excel is often enough.
One of the key is the input power. The out voltage is:

Vout = K(Tobs+Te)B G Gamma

K : Boltzmann Constant
Tobs: the brilliance of the target
Te: Input Noise Temperature of Your Radiometer
B: Noise Bandwidth
G: overall RF gain
Gamma: the sensitivity of the square law detector

Do at least two simulation: one for Tobs=3K and the second with Tobs=the maximum expected temperature. The latter case should shows a voltage less than the non linearity knee ( say less than 5 mV).

Another key is the radiometer sensivity.
The sensivity equation (less the drift and 1/f noise) is:

DT = (Tobs+Te)/(B*tau)

DT : smallest brillance observable
B : Noise Bandwidt
Tau : post-detection time constant.

enjoy :D

Thanks dear Mariotti,

my problem is that I can't realize the input noise source with variable temperature and wide band, and I need to determine the gain variations of the whole system. I think this factor its very important to calculate the actual sensitivity of radiometer.
Do you have any idea about Wideband noise envelope-transient simulation in radiometers?.... I need your help dude

Thanks dear