Doppler Microwave Cavity Monitor for Particulate Loading

A real-time particulate loading monitor using a multimode microwave cavity is described and analyzed. Microwave power in the cavity volume is scattered with a Doppler shifted frequency by particulates suspended in a gas flowing through the cavity. Detection of the scattered radiation by beating it with the nonscattered radiation provides an indication of the particulate loading. A proof-of-concept experimental setup is described with the obtained results. The monitoring system is not very sensitive to particulates smaller than 1 ¿m. However, it is very well suited to operations where the effluent gas is under high pressure and temperature.