In some cases, such as at a boiler tank and other large-size mechanical systems, it is more realistic to employ a non-contacting sensor to detect small displacement or vibration. In this paper, a non-contacting sensor for monitoring small displacement or vibration based on measurement of antenna reflection coefficient is proposed. A theoretical and numerical study is performed to investigate the proposed method and to determine the post processing method associated with the antenna reflection coefficient data. To avoid the ambiguity in the measured data, the detection of both the magnitude and phase components of the antenna reflection coefficient is required to compute the small displacement of the target. The distance between antenna and target has to be determined in order to minimize the ambiguity range in the data. The frequency domain observation is more appropriate for determining the amplitude and frequency of the target vibration. Magnitude detection, phase detection and Fourier analysis are used as main tools in the post-processing part of the proposed method.
1. Lee, Y. S., P. N. Pathirana, C. L. Steinfort, and T. Caelli, "Monitoring and analysis of respiratory patterns using microwave doppler radar," IEEE Journal of Translational Engineering in Health and Medicine, Vol. 2, 1-12, 2014, doi: 10.1109/JTEHM.2014.2365776. doi:10.1109/JTEHM.2014.2365776
2. Lee, Y. S., P. N. Pathirana, R. J. Evans, and C. L. Steinfort, "Noncontact detection and analysis of respiratory function using microwave doppler radar," Journal of Sensors, Vol. 2015, Article ID 548136, 13 pages, 2015, doi:10.1155/2015/548136.
3. Hsieh, C. H., Y. F. Chiu, Y. H. Shen, T. S. Chu, and Y. H. Huang, "A UWB radar signal processing platform for real-time human respiratory feature extraction based on four-segment linear waveform model," IEEE Transactions on Biomedical Circuits and Systems, Vol. 10, No. 1, 219-23, Feb. 2016, doi:10.1109/TBCAS.2014.2376956. doi:10.1109/TBCAS.2014.2376956
4. Li, C., J. Ling, J. Li, and J. Lin, "Accurate doppler radar noncontact vital sign detection using the RELAX algorithm," IEEE Transactions on Instrumentation and Measurement, Vol. 59, No. 3, 687-695, Mar. 2010, doi:10.1109/TIM.2009.2025986. doi:10.1109/TIM.2009.2025986
5. Xiong, Y., S. Chen, X. Dong, Z. Peng, and W. Zhang, "Accurate measurement in doppler radar vital sign detection based on parameterized demodulation," IEEE Transactions on Microwave Theory and Techniques, Vol. 65, No. 11, 4483-4492, Nov. 2017, doi:10.1109/TMTT.2017.2684138. doi:10.1109/TMTT.2017.2684138
6. Perrone, G. and A. Vallan, "A low-cost optical sensor for noncontact vibration measurements," IEEE Transactions on Instrumentation and Measurement, Vol. 58, No. 5, 1650-1656, May 2009, doi: 10.1109/TIM.2008.2009144. doi:10.1109/TIM.2008.2009144
7. Luzi, G., M. Crosetto, and E. Fernandez, "Radar interferometry for monitoring the vibration characteristics of buildings and civil structures: Recent case studies in Spain," Sensors, Vol. 17, 669, 2017, doi:10.3390/s17040669. doi:10.3390/s17040669
8. Moll, J., K. Bechtel, B. Hils, and V. Krozer, "Mechanical vibration sensing for structural health monitoring using a millimeter-wave doppler radar sensor ," 7th European Workshop on Structural Health Monitoring, Nantes, France, Jul. 2014.
9. Vinci, G., et al., "Six-port microwave interferometer radar for mechanical vibration analysis," 2013 European Microwave Conference, 1599-1602, Nurember, 2013, doi: 10.23919/EuMC.2013.6686978.
10. Buscarino, A., L. Fortuna, C. Famoso, and M. Frasca, "Passive and active vibrations allow self-organization in large-scale electromechanical systems," International Journal of Bifurcation and Chaos, Vol. 26, No. 7, 1650123.1-10, 2016, doi: 10.1142/S0218127416501236. doi:10.1142/S0218127416501236
11. Budge, M. C., Jr. and S. R. German, Basic Radar Analysis, Artech House, 2015.
12. Mahafza, B. R., Radar Systems Analysis and Design Using Matlab, Taylor & Francis Group, CRC Press, 2013.
13. Skolnik, M. I., Radar Handbook, 3rd Ed., McGraw-Hill, 2008.
14. Pramudita, A. A., "Input impedance model of planar dipole antenna for wireless body area network (WBAN)," 2016 22nd Asia-Pacific Conference on Communications (APCC), 66-69, Yogyakara, Sep. 2016, doi:10.1109/APCC.2016.7581495.
15. Kraus, D., Antennas, 1st Ed., McGraw Hill, 1965.
16. Su, M.-B., I-H. Chen, and C.-H. Liao, "Using TDR cables and GPS for landslide monitoring in high mountain area," Journal of Geotechnical and Geoenvironmental Engineering, Vol. 135, No. 8, 1113-1121, Aug. 2009. doi:10.1061/(ASCE)GT.1943-5606.0000074
17. Or, D. and S. B. Jones, "Time domain reflectometry (TDR) applications in Earth sciences," IEEE Antennas and Propagation Society International Symposium, (IEEE Cat. No. 02CH37313), Vol. 2, 324-327, 2002, doi: 10.1109/APS.2002.1016090.
18. Kim, S. M., J. H. Sung, W. Park, J. H. Ha, Y. J. Lee, and H. B. Kim, "Development of a monitoring system for multichannel cables using TDR," IEEE Transactions on Instrumentation and Measurement, Vol. 63, No. 8, 1966-1974, Aug. 2014, doi:10.1109/TIM.2014.2304353. doi:10.1109/TIM.2014.2304353