Non-destructive Dielectric Measurement of Solid Lossy Dielectric Material Using Open-Ended Waveguide Infilled with Low-Loss Dielectric Material

Hidetoshi EBARA  Daisuke MIKI  Teruo ONISHI  Shinji UEBAYASHI  Osamu HASHIMOTO  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.1   pp.30-37
Publication Date: 2006/01/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.1.30
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Near-Field and Far-Field Electromagnetic Absorption and Shielding and Related Technologies)
dielectric measurement,  open-ended waveguide,  solid phantom,  FDTD method,  impedance matching,  

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This paper proposes a non-destructive dielectric measurement method for a solid lossy dielectric material with sufficiently large dimensions compared to the wavelength. The proposed non-destructive measurement method employs an open-ended waveguide infilled with a low-loss dielectric material at the end of the waveguide. A numerical model of the open-ended waveguide attached to the surface of a solid dielectric material is simulated using the FDTD method. The reflection coefficient is calculated while the complex permittivity of the solid lossy dielectric material is varied. A permittivity estimation chart representing the relationship between the complex permittivity and the reflection coefficient is derived at 2 GHz. The measured reflection coefficient is plotted on the permittivity estimation chart. The chart indicates that the reflection coefficient varies drastically according to the variation in the complex permittivity of the solid dielectric material if a low-loss dielectric material is used. As a result, it became possible to estimate the complex permittivity of the solid lossy dielectric material by measuring the reflective coefficient. The estimated complex permittivity using the proposed method is comparable to the measured complex permittivity using the S-parameter method employing a coaxial line.