Thermometry of lossy microstriplines by correlation radiometry

The notion of correlation temperature resulting from the thermal noise of a passive symmetrical lossy two-port is applied to microwave microstriplines made lossy by implantation of small-size resistors. The case of an isothermal line is considered, followed by the case of a hot spot created on the line in which it is possible to emphasise its contribution in terms of correlation temperature. The study is illustrated by extensive experimental verifications in the bandwidth of 2-4 GHz. A method of inversion is presented based on Kalman filtering of the radiometric data, and leading to thermal profiling along the microstriplines