Microwave Eight-Port Reflectometer for Air Pollution Sensor

In this paper, a microwave reflectometer incorporating eight-port network is presented. It is designated to measure reflection coefficient of an air pollution sensor. The reflectometer operates at the frequency of 5.8 GHz and exhibits simplified circuitry with respect to previously reported solutions. Simultaneously, it provides tunable power distribution scheme, which serves for optimizing the measurement uncertainty for a chosen sensor. As a consequence, the uncertainty can be greatly minimized comparing to other reflectometers with fixed power distribution scheme. The developed eight-port has been fabricated and used to developed measurement setup. Finally, the reflectometer has been calibrated for two exemplary settings proving experimentally its tuning capability.