Polarimetric Microwave Sensor for Angular Speed Measurement

This article presents a design methodology and prototyping of an angular speed sensor based on microwave polarimetry. The detection mechanism relies on the transmission response of a dual-polarized circular aperture irradiating an array of regularly spaced copper traces printed on a PCB. The generated response is a regular pulse train defined by the location of the copper trace with reference to the center of the circular aperture. While the angular speed sensor can be sampled at any rate and for any time length, the detector response was acquired within a 1-s duration with the circular aperture response effectively sampled at 10 kHz for demonstration purposes. The acquired response was analyzed in the frequency domain using the fast Fourier transform (FFT) and the rotor speed was obtained from the frequency spectrum of the acquired pulse train. To demonstrate the working principle of the detection system, the printed PCB rotor, which occupies an area of 84.64 cm2, was attached to a rotary stage set to rotate at certain angular speeds, including but not limited to 62 r/min. In all the speed settings, the speeds were detected in 1 s with a worst case error of ±0.625 r/min.