The National Institute of Metrology (NIM) of China is a pioneer in radio frequency (RF) and microwave power metrology. In March 2018, Standards and Calibration Laboratory (SCL) has successfully transferred the technology from NIM to set up a new microcalorimeter system as the primary coaxial RF/microwave power measurement standard for Hong Kong. Experts from NIM, led by Prof Cui Xiaohai, helped to set up the system and provided technical exchange with the technical team in SCL. Prof Cui is the Head of the Microwave Laboratory at NIM and a world respected researcher in the RF/microwave field.

The microcalorimeter system operates in the frequency range of 10 MHz to 18 GHz. Its advanced design allows small temperature differences of power sensors arising from application of RF/microwave and direct current (DC) power to be measured. A Type-IV power meter designed by NIM is integrated in the system for controlling the RF/microwave and DC powers in an equilibrium status during calibration. Software developed by NIM enables the system to be operated in an automatic manner. It can be used to calibrate the effective efficiency of thermistor mount type power sensors, thereby establishing the metrological traceability of RF/microwave powers to DC power, which in turn is traceable to the two quantum standards in SCL – the Josephson Array Voltage Standard (JAVS) and Quantum Hall Resistance Standard (QHRS).

The performance of the new system was validated by calibrating a thermistor mount power sensor that had been calibrated earlier at NIM. The new system can benefit the local industry by underpinning more accurate RF/microwave power measurement.