Measurement System Of Broadband National Power Standard

High frequency and microwave power are two fundamental parameters of electronic measurement. In order to approach our national electronics measurement to the International System of Units (SI) and ensure the result consistency, establishing the national standards for high-frequency and microwave power measurement is very important. Hence, the study of high frequency and microwave power measurement is of great theoretical and practical value.Since the original power standard in our country is unable to meet the standard of domestic demand, setting up a new broadband national power standard is critical. The measurement system used in the latest primary power standard was mainly studied in this paper. Ensuring accuracy of measurement and minimizing the system time constant are the key work of the research.The classical power measurement methods based on the theory of the calorimetric-substitute technique and the principles of control systems were analyzed. The importance of the use of auxiliary control system to shorten the time constant was discussed. The experimental results show that power measurement time of measurement system of broadband national power standard can be shortened to 20 minutes without loss of measurement accuracy.The Characteristics of thermoelectric sensor and the principles of the PID controller were also studied. A high sensitivity thermometric system and a high stability temperature control system were designed and established. Practical tests verified that the performance of the control system is better than 0.1m℃/h.Based on the characteristics of semiconductor thermistor, a new method of temperature measurement was given after the impact factors of measurement accuracy were carefully analyzed. Experiments proved that the new method has greatly inhibited the measurement error caused by the change of environmental temperature.The disadvantages of traditional DC substitute method were analyzed, as well as the causes of measurement errors. The contradiction between high loop gain and noise rejection were resolved. It is believed that this work provided great potential for the further enhancement of accuracy in power measurement.