Re: how to get the noise figure of the antenna by measuremen
noise figure of the antenna????
Is it a small beam corrugated horn ?
In this case a calibrated radiometer and 2 temperature standard loads are required and the measurement is very difficult.
"Difficult" means that the uncertainty is larger tha the observed value.
Otherwise, in general and for all type of antenna, you may consider the antenna as a lossy line.
After Gain measurement , find efficency, then extract all "non lossy" coefficients (phase efficiency. , xpol efficiency., illumination efficiency etc.), then you'll have the loss efficiency. Now, after Impedance Measurement, find the Available Gain of the antenna, Gav=Gloss/(1-Γ²), then, if you prefere, format the result in dB.
The Available Gain of the antenna is numerically the same of Noise Figure only when the antenna is 290K hot.
But, since the available gain is usually very small, Noise Figure don't change a lot if physical temperature change.
Conclusion:
Noise Figure is measurable only if a switched hot/cold noise source exist.
The method suggested is a measurement. More exactly is a processing of a measurement. It'is not a simulation or a computing.
Ref.
Clarricoats - Olver, Corrugated horns for microwave antennas, Peter Peregrinus, pag. 8
Kraus, Radioastronomy, chap. Receivers
Agilent, AN57-1