On the development of a multifunction millimeter-wave sensor for displacement sensing and low-velocity measurement

• Published in: IEEE transactions on microwave theory and techniques Vol. 52; no. 11; pp. 2503 - 2512
• Main Authors: KIM, Seoktae, NGUYEN, Cam
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.11.2004; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Circuit properties; Displacement measurement; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Frequency; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated circuit measurements; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave integrated circuits; Millimeter wave integrated circuits; Millimeter wave measurements; Millimeter wave technology; millimeter-wave sensor; MMICs; Physics; radio interferometry; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Studies; Testing, measurement, noise and reliability; Velocity measurement; Wavelength measurement; Millimeter wave radiation; Manufacturing processes; radio interferometry; Circuit design; millimeter-wave sensor; Displacement sensor; Displacement measurement; Signal processing; Velocity measurement; MMIC; Testing; Interferometry
• DOI: 10.1109/TMTT.2004.837153
• ISSN: 0018-9480

A new multifunction millimeter-wave sensor operating at 35.6 GHz has been developed and demonstrated for measurement of displacement and low velocity. The sensor was realized using microwave integrated circuits and monolithic microwave integrated circuits. Measured displacement results show unprecedented resolution of only 10 /spl mu/m, which is approximately equivalent to /spl lambda//sub 0//840 in terms of free-space wavelength /spl lambda//sub 0/, and maximum error of only 27 /spl mu/m. A polynomial curve-fitting method was also developed for correcting the error. Results indicate that multiple reflections dominate the displacement measurement error. The sensor was able to measure speed as low as 27.7 mm/s, corresponding to 6.6 Hz in Doppler frequency, with an estimated velocity resolution of 2.7 mm/s. A digital quadrature mixer (DQM) was configured as a phase-detecting processor, employing a quadrature sampling signal-processing technique, to overcome the nonlinear phase response problem of a conventional analog quadrature mixer. The DQM also enables low Doppler frequency to be measured with high resolution. The Doppler frequency was determined by applying linear regression on the phase sampled within only fractions of the period of the Doppler frequency. Short-term stability of the microwave signal source was also considered to predict its effect on measurement accuracy.