4. High-frequency power detectors

Power detection is an important sector of high-frequency (HF) measurement applications and technologies. Existing power meters are designed for use in test and measurement applications as end-of-line instruments, since they use a power-absorbing terminal sensor. There are three types of sensor on the market for RF and microwave power measurements: thermistors, thermocouple detectors and diode detectors. Thermistors and thermocouples are based on the conversion of RF power into heat, and on temperature measurement. In diode detectors, power measurement is based on the non-linear current-voltage characteristics of fast Schottky diodes; at low powers, the diodes respond to the RMS value of the signal and produce a DC output proportional to the applied RF power. Thermistors are widely used as power transfer standards in calibration laboratories, but in many other applications they have been...