The article presents the concept of using VNA (Vector Network Analyzer) to measure the temperature of the MOS transistor junction. The method assumes that the scattering parameters of the network consisting of the transistor depend on the temperature. The tests confirmed the influence of temperature on the S11 parameter and the input network capacity during ambient temperature changes in the range of 35–70 °C. Measurements were made for the gate-source (G-S) input of the system. The measurements were carried-out with the transistor in the ON/OFF states. In order to validate the measurements, the temperature of the tested element was recorded with the MWIR Cedip-Titanium thermal imaging camera.

This paper presents a new method for measuring RMS values of AC (Alternative Current) in power lines using an infrared camera. An IR camera registers thermal images in time with an appropriate frame rate in order to calculate the spectrum of the temperature signal of a power cable. For the European standard, the amplitudes of the harmonics for f ≈ 100 Hz correlate to the power dissipated in a conductor. The FFT and RMS analysis for different current values were performed. The obtained results allow plotting the calibration curve of temperature changes versus the RMS values of the current flowing in wire. They confirmed the linear relation between the 100 (Hz) spectral component of the temperature and the square value of the RMS current. This method has unique advantages. It is non-contact and makes it possible to estimate the RMS current regardless of the ambient background radiation and convection cooling conditions having a significant impact on overhead lines, in particular.

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