Measurement of the Effective Efficiency of Thermoelectric Power Sensors Using a Thermal Voltage Converter From 1 kHz to 1 MHz

Frequency extension of the RF power standard using a thermal voltage converter (TVC) has been accomplished down to 1 kHz. To measure the effective efficiency of a thermoelectric power sensor (PS), a reference TVC with a built-in tee is employed. A modified TVC measurement system enables us to automatically measure the dc substituted power of the PS as well as the RF voltage of the reference TVC in terms of RF- dc difference. The standard RF power is obtained from the RF conductance and RF voltage at the input of the PS. A vector network analyzer is used to measure the RF conductance, which causes a significant measurement uncertainty. Associated theoretical consideration and the uncertainty analysis are included. The expanded uncertainty evaluated from the Guide to the Expression of Uncertainty in Measurement (GUM), i.e., the law of propagation of uncertainty is 1.5% ($k = 1.84$ , 95% level of confidence, trapezoidal distribution) in the frequency range of 1 kHz to 1 MHz. Because the measurement model includes a nonlinear input quantity, the RF conductance, a Monte Carlo method is employed. Simulated results give the measurement uncertainty of 1.6% at a 95% level of confidence, which show good agreement with the GUM.