This paper presents a technique based on time domain reflectometry (TDR) to determine the dielectric and magnetic properties of lossless materials fitted inside a transmission line section. The proposed method involves three different line terminations namely open, short, and matched load. The described technique involves placing a sample of material under test (MUT) inside a terminated transmission line and exciting this with a vector network analyser from the other end to measure the reflection coefficient. Results achieved from a transmission line model were compared with numerical simulations obtained using CST Microwave Studio. The comparison shows that the electric and magnetic properties of a material may be determined precisely with this technique. Experimental results are also presented to validate the proposed method. Estimates of measurement errors, resulting from sample length uncertainty, vector network analyser uncertainty, and open-end inaccuracy are discussed.
Iman O. Farhat,
Charles V. Sammut,
"Preliminary Experimental Measurements of the Dielectric and Magnetic Properties of a Material with a Coaxial TDR Probe in Reflection Mode," Progress In Electromagnetics Research M,
Vol. 91, 111-121, 2020. doi:10.2528/PIERM19111904
1. Cerny, R., "Time-domain reflectometry method and its application for measuring moisture content in porous materials: A review," Measurement, Vol. 42, No. 3, 329-336, 2009. doi:10.1016/j.measurement.2008.08.011
2. Fellner-Feldegg, H., "Measurement of dielectrics in the time domain," The Journal of Physical Chemistry, Vol. 73, No. 3, 616-623, 1969. doi:10.1021/j100723a023
3. Dalton, F. N. and M. Th. van Genuchten, "The time-domain reflectometry method for measuring soil water content and salinity," Geoderma, Vol. 38, No. 1, 237-250, 1986. doi:10.1016/0016-7061(86)90018-2
4. Nicolson, A. M. and G. F. Ross, "Measurement of the intrinsic properties of materials by time-domain techniques," IEEE Transactions on Instrumentation and Measurement, Vol. 19, No. 4, 377-382, 1970. doi:10.1109/TIM.1970.4313932
5. Agilent 85070E Dielectric Probe Kit 200 MHz to 50 GHz. Technical Overview, Agilent Technologies: Santa Clara, CA, USA, 2008.
6. Tan, X., J. Wu, J. Huang, M. Wu, and W. Zeng, "Design of a new TDR probe to measure water content and electrical conductivity in highly saline soils," Journal of Soils and Sediments, Vol. 19, No. 4, 377-382, 1970.
7. Jha, S. N., K. Narsaiah, A. L. Basediya, et al. "Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods — A review," Journal of Food Science and Technology, Springer, 2017.
8. Andrea, C., B. De Egidio, and C. Giuseppe, Broadband Reflectometry for Enhanced Diagnostics and Monitoring Applications, Vol. 93, Springer, 2011.
9. Persico, R., F. Soldovieri, and R. Pierri, "Convergence properties of a quadratic approach to the inverse scattering problem," Journal of Optical Society of America Part A, Vol. 19, No. 12, 2424-2428, 2002. doi:10.1364/JOSAA.19.002424
10. Baker-Jarvis, J., M. D. Janezic, J. H. Grosvenor, Jr., and R. G. Geyer, "Transmission/reflection and short-circuit line method for measuring permittivity and permeability," National Institute of Standards and Technology Technical Note, 1355-R, 1993.
11. Persico, F. and R. Pieraccini, "Measurement of dielectric and magnetic propperties of materials by means of a TDR probe: A preliminary theoretical investigation in the frequency domain," Near Surface Geophysics, Vol. 16, No. 2, 118-126, 2018. doi:10.3997/1873-0604.2017046
12. Persico, R., I. Farhat, L. Farrugia, C. Sammut, and S. D’Amico, "An innovative use of TDR probes. First numerical validations with a coaxial cable," Environmental and Engineering Geoscience, 2018.
13. Staszek, K., et al., "Complex permittivity and permeability estimation by reflection measurements of open and short coaxial transmission line," Microwave and Optical Technology Letters, Vol. 56, No. 3, 727-732, 2014. doi:10.1002/mop.28132