Title :
Characterization of highly dispersive materials using composite coaxial cells: electromagnetic analysis and wideband measurement
Author :
Huang, Jifu ; Wu, Ke ; Morin, Patrick ; Akyel, Cevdet
Author_Institution :
Dept. de Genie Electr. et de Genie Inf., Ecole Polytech., Montreal, Que., Canada
fDate :
5/1/1996 12:00:00 AM
Abstract :
In this work, theoretical modeling and experimental characterization of composite coaxial-line cells are made for accurate dielectric measurement. The coaxial cells are designed such that highly dispersive materials can be characterized over a wide band of frequencies. In addition, a transmission line matrix (TLM) algorithm with a new type of node is proposed for electromagnetic analysis of the complex composite geometry of the measurement cells. Such a hybrid-mode simulation allows the electrical performance of the proposed cells to be determined for a variety of complex permittivity measurements. The proposed node in the cylindrical coordinate not only accommodates cylindrical coaxial discontinuities in the cell, but also describes the frequency-dependent properties of material. Experiments on a network analyzer were done with a number of APC-7 coaxial cells and various liquid samples to verify the wideband characteristics of the technique. It is found both theoretically and experimentally that the sample volume can be adjusted to ensure a wideband sensibility of the S-parameters. A sensitivity factor is also defined to characterize the frequency response of the coaxial cells. Such an electromagnetic analysis (direct problem) can be used in extracting unknown dielectric characteristics of a material (inverse problem) based on a recently proposed generic approach
Keywords :
S-parameters; coaxial cables; dispersion (wave); electromagnetic wave propagation; microwave measurement; permittivity measurement; transmission line matrix methods; S-parameters; composite coaxial-line cells; dielectric measurement; direct problem; dispersive materials; electromagnetic analysis; frequency response; hybrid-mode simulation; inverse problem; network analyzer; permittivity measurement; sensitivity factor; transmission line matrix algorithm; wideband measurement; Coaxial components; Composite materials; Dielectric materials; Dielectric measurements; Dispersion; Electromagnetic analysis; Frequency; Permittivity measurement; Transmission line matrix methods; Wideband;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on