Method for measuring the noise figure of a device under test with a network analyser

Method for measuring the noise figure (FDUT) of a device under test using only a noise source and a network analyzer, said device under test being characterized by power amplification (GDUT) and forward-S-parameter (S21) values and comprising first and second ports, said network analyzer comprising first and second measuring ports and being characterized by inaccuracy (k) and internal noise (NNWA) values, said method comprising:

• determining the inaccuracy (k) and the internal noise (NNWA) of the network analyzer from a measured value (PMessOFF), measured in a calibration process with the noise source switched off, at the first measuring port of the network analyzer connected to the noise source and a measured value (PMessON), measured with the noise source switched on, at the first measuring port of the network analyzer connected to the noise source;
• determining the power amplification (GDUT) of the device under test from a measured forward-S-parameter (S21) of the device under test, while the first port is connected to the first measuring port of the network analyzer and the second port is connected to the second measuring port of the network analyzer;
• measuring, at the first port of the network analyzer, a measured value (PMess) of output noise power applied at the first port of the device under test, while the second port of the device under test is connected to the second port of the network analyzer and is not excited by the network analyzer with a generator signal in the form of a noise signal;
• and
• calculating the noise figure (FDUT) from the measured value (PMess) of the output noise power, the power amplification (GDUT) of the device under test, the inaccuracy (k), the internal noise (NNWA) of the network analyzer, and thermal noise (N0) of a 50-Ω resistor system.