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Total Power Radiometer - help with simulations needed

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raed_microwave

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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
 

Re: Total Power Radiometer

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
 
Re: Total Power Radiometer

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










sergio mariotti said:
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
Click to expand...
 

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