A microwave technique for detecting water deposits in an air flow pipelines

A simple microwave method is used to determine thin layers of water inside the air or compressed-air carrying pipes of pneumatic systems. The technique proposed here is based on the shift in the resonant frequency with the changing air-water ratio within the pipe. A calibration chart relating the resonant frequency and thickness of water layer is presented and experimentally verified. Experimental results agreed well with the simulated response, particularly for thin water layers, which are difficult to detect accurately using existing methods.