Measurement of the Noise Temperature of a Mismatched Noise Source

A method is suggested that can measure the available power (or the effective temperature) of a noise generator independent of its reflection coefficient. A system utilizing a compensation generator and a tuned three-port circulator is constructed at X-band and evaluated for a noise generator of about 10 000/spl deg/K. The error analysis and the experimental results indicate that the effective temperature of this generator, with a reflection coefficient of 0.5, can be measured within 0.6 percent in addition to the uncertainty of a standard needed to calibrate the system.