A Radio Frequency Polarimetric Sensor for Rotating Machine Analysis

The analysis of rotating machines during their test and characterization phases provides information essential for their design. Afterward, the monitoring of rotating machines operating in production is increasingly popular for condition based maintenance programs. Typically, contact accelerometers or strain gauges are physically attached to rotating machine parts (rotors, stators, housing, etc.) and/or proximity sensors are mounted very near to rotating shafts to capture data on periodic motions and vibrations. Radio frequency signals offer a noncontact, remote-sensing alternative. The temporally changing polarization of a reflected or scattered radio frequency signal can be analyzed to provide suitable information for rotating machine analysis. This paper will present the theory and practical application for using radio frequency polarimetry in analyzing rotating machines. A common desktop fan will be measured in normal operating condition and in simulated faulty conditions to demonstrate this technology's remote-sensing capabilities.