Development of RF Power Sensor Measurement System Using VNA Method and Heating Block

Most National Metrology Institutes (NMIs) and calibration laboratories measure radio frequency (RF) power sensors by using the direct comparison transfer method. Instruments for the direct comparison transfer method consist of signal generator, power splitter, power sensor, and power meter. The method can be applied in a vector network analyzer (VNA) to measure RF power sensors. The VNA consists of a signal generator, directional coupler, and receiver. The power splitter in the conventional direct comparison transfer can be replaced by the directional coupler of VNA. Measurements of RF power sensors in the frequency range of 10 MHz to 18 GHz have been developed at the National Standardization Agency of Indonesia using the VNA system. The measurement system is intended to build measurement traceability of RF power in Indonesia. Measurement results of calibration factor of RF power sensor using VNA system showed a good agreement with the conventional direct comparison transfer method. A new temperature control system using a heating block is proposed to stabilize the temperature of RF power sensor calibration, particularly for thermistor mount. The temperature control has improved measurement stability of the thermistor mount. Measurement uncertainty of the thermistor mount has been decreased almost 20% by using the temperature control.