"JOURNAL OF RADIO ELECTRONICS" (Zhurnal Radioelektroniki ISSN 1684-1719, N 9, 2018

contents of issue      DOI  10.30898/1684-1719.2018.9.6     full text in Russian (pdf)  

Waveguide method for measuring electromagnetic parameters of materials in the microwave range and  estimating the measurement error

  

M. P. Parkhomenko, D. S. Kalenov, I. S. Eremin, N. A. Fedoseev, V. M. Kolesnikova, Yu. L. Barinov

Fryazino Branch of Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences,
Vvedensky Sq.1, Fryazino Moscow region 141190, Russia

 

The paper is received on August 31, 2018

 

Abstract. Resonator and waveguide methods, as well as the free-space method, are widely used to determine the electromagnetic parameters of materials (complex permittivity and permeability). Here a waveguide method is considered that allows one to determine the parameters of materials in a wide frequency range. However, there are a number of factors that significantly restrict the application of this method. Modern measurement equipment is based on a rectangular metal waveguide in which the Í10 mode propagates. When the waveguide is filled with a material to be investigated, there always exists an air gap between the sample and the wide wall of the waveguide, which leads to a sharp jump in the electric field strength at the boundary between the material of the sample and air and strongly affects the accuracy in determining the electromagnetic parameters. This factor is especially manifest when measuring materials with large value of the real part of the complex permittivity. In the paper, the results of a numerical experiment are presented on the determination of complex permittivity by the waveguide method in the centimeter and millimeter ranges. Calculations are carried out for materials with real part of permittivity ε1 = 10 and tangent loss of tanδ 0.1–0.2. It is shown that even a small air gap between a sample and the broad wall of the waveguide leads to a jump in the electric field strength when passing from the material to air and introduces a significant error to the results of measurements. To reduce this error and enhance the possibilities of the waveguide method, it is proposed that this gap be filled with electrically conducting paste. The results of calculations in the presence of a gap and when the gap is filled with the electrically conducting paste are compared. For example, for a material with ε1 = 10 and tangent loss of tanδ 0.1, the maximum error of measurements in the millimeter-wave range in the presence of a gap of 0.1 mm is 5.5% for ε1 and 11 % for tanδ. When the gap is filled with the paste, this error reduces to 0.5% for both ε1 and tanδ.

Key words: complex permittivity, tangent loss, waveguide method, electrically conducting paste.

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For citation:
M. P. Parkhomenko, D. S. Kalenov, I. S. Eremin, N. A. Fedoseev, V. M. Kolesnikova, Yu. L. Barinov. Waveguide method for measuring electromagnetic parameters of materials in the microwave range and  estimating the measurement error. Zhurnal Radioelektroniki - Journal of Radio Electronics. 2018. No. 9. Available at http://jre.cplire.ru/jre/sep18/6/text.pdf

DOI  10.30898/1684-1719.2018.9.6