volume | PIER Journals

Abstract

To achieve accurate characterization of a dielectric sample, an improved approach to the cylindrical cavity perturbation technique is proposed, with particular emphasis on the depolarization factor. The problem arises from the depolarized field within the sample when its height is smaller than that of the cavity, and it depends on the sample's geometry and the orientation of the applied field lines. Two models are examined: the proposed model, based on the resolution of Maxwell's equations, and the ellipsoidal model refined through image theory. The objective is to enhance the accuracy of complex permittivity extraction for lossy dielectric materials. Standard low-loss and high-loss materials (Al2O3, Teflon, and SiC) with various shapes (rod, needle, disk and sphere) are analyzed using HFSS simulations and MATLAB computations. The maximum sample volume is also evaluated for different geometries and material types to ensure accurate permittivity estimation. Low-loss materials generally allow a larger sample volume than high-loss ones, and provide more consistent results for permittivity extraction. Experimental measurements were further performed on disk-shaped polyamide and ceramic samples, demonstrating that the proposed approach provides improved permittivity estimation, particularly for high-loss and disk-shaped dielectric materials.

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Ms. Khawla Ghorab

Dr. Rawdha Thabet

Prof. Junwu Tao

Professor Mohamed Lahdi Riabi

Dr. Tan Hoa Vuong