Development of measurement system for calibration of microwave power sensor

• Main Author: Mook, Wei Yao.
• Other Authors: Lin Zhiping
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Power electronics
• Online Access: http://hdl.handle.net/10356/15751
• Institution: Nanyang Technological University

In the calibration of microwave power sensor, National Metrology Centre (NMC) employs the direct power comparison transfer technique to transfer the effective efficiency or calibration factor of a reference standard power sensor to an unknown power sensor. Consequently, three mathematical models can be used to model the transfer. Through these mathematical models, the unknown power sensor‟s calibration factor or effective efficiency can be derived and measurement uncertainty can be improved by mathematically correcting for the impedance mismatch between the source and the power sensor connected to the source. Since some of the quantities used in the mathematical models are complex number in nature, this project is therefore extended to include the possibility of expressing the mathematical model in the magnitude & phase and real & imaginary representation. While the transfer technique described in this report is so called direct and yet potentially accurate in comparing power sensor, this technique when performed manually will however require a relatively long time to complete. Hence, the objective of this project is to develop software suitable for automating and optimizing the processes which eventually result in higher production efficiency. Therefore, a detailed presentation will be given in this report on the program developed during the project which includes the capability to control the signal source, power meter and digital multi-meter simultaneously for acquisition of the required data, process the acquired data using the mathematical models derived and evaluating the uncertainty in measurement. In addition, many separate programs were also built in to streamline the work process and to minimize the error introduced during the process of manual operation. Through comparison of result from the program with result from other national metrology institution, it can be concluded that the result obtained from the program is comparable to the other national metrology institutions and traceable to the International System of Units (SI). Moreover, the program developed is already operational in NMC.