Enhancement of microwave power sensor measurement with adaptors

• Main Author: Qiu, Tie
• Other Authors: Lin Zhiping
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: http://hdl.handle.net/10356/60425
• Institution: Nanyang Technological University

Calibration is important in microwave power sensor measurement, since it can improve the overall accuracy of the measurement. A calibration factor is used as a correction factor; it describes both the effective efficiency and reflection coefficient of the power sensor. Generally, the calibration factor will be used in the calibration transfer from a reference standard to the device under test. And the direct comparison transfer technique is the simplest and most evident method to achieve the calibration of power sensors by using calibration transfer. Nowadays, for further developments of the direct comparison technique, different adaptors (attenuators) could be used in some implementations. Therefore, their effects should be investigated since they can introduce additional measurement uncertainties. In this report, the effects of different adaptors on microwave power sensor calibration with direct comparison technique have been studied. And the calibrations are implemented with a mathematical model proposed by NMC recently. To verify its accuracy in calculating the calibration factor, a comparison is carried out between the mathematical model proposed by NMC and other research. The comparison indicates that the equation derived in the model is accurate to calculate the calibration factor of microwave power sensors. For its implementations, a 0 dB adaptor, 10 dB, 20 dB and 30 dB attenuators are used to evaluate the effects from different adaptors. Results show that when the attenuation of an adaptor increases, the expanded uncertainty of the calibration factor increases correspondingly, following the Guide to the Expression of Uncertainty in Measurement (GUM). Moreover, to verify the uncertainty results of GUM, the Monte Carlo Method is used to simulate the expanded uncertainty of the calibration factor as well. On the other hand, for the enhancement of the existing software used to execute the calculation and simulation in calibrations, a new software is developed based on the LABVIEW programming software. In addition, comparisons are made between the calculation and simulation results of the new and previous software in order to check the accuracy.