Tapan K. Bose

Broadband complex permittivity measurements by time-domain spectroscopy

The complex permittivity measurements of some materials, taken by using the time-domain reflectometry (TDR) method, are presented. As an example of the wide frequency measurement capability, both at the radio and microwave frequencies, the complex permittivity measurement of a liquid crystal is presented in the frequency range between 100 kHz and 1 GHz. The measurement of an ionic water-in-oil microemulsion system is given to describe the case of a conductive sample. From the measurement of this system, it is clear that the TDR technique can be used to measure the complex permittivity of a sample with high DC conductivity. Even if the sample has a small dielectric absorption hidden behind the high DC conductivity, the method should be able to distinguish between the two. Complex permittivity measurements of strongly polar liquids are presented to show the highest frequency attainable by the TDR system. The result indicates that the complex permittivity can be measured up to 25 GHz with sufficient accuracy if the cutoff frequency of the TDR system is higher than 25 GHz. This high-frequency limit is due to the limitation of the system given by the performance of the sampling system. >

New dielectric method for the measurement of physical adsorption of gases at high pressure

A new method for the measurement of gas adsorption at high pressure is described in detail. The method is based on dielectric virial coefficients and it takes advantage of the dielectric technique for the accurate measurement of the compressibility factor of gases at high pressure. The method is simple, self‐sufficient, easy to use, and permits precise measurement of the density of nonideal gases. Adsorption measurements of methane on BPL‐activated carbon as a function of pressure at 25u2009°C are reported.

Development of a dipole probe for the study of dielectric properties of biological substances in radiofrequency and microwave region with time-domain reflectometry

A time-domain reflectometric (TDR) technique with a needle-like dipole probe is described for dielectric measurements of biological substances. The probe is tested by measuring some known liquids. The dielectric measurements made on beef muscle and fat compare favorably with existing literature values of human muscle and fat.

Measurement of the dielectric properties of materials by using time domain reflectometry

The authors present some TDR (time-domain-reflectometry) applications for complex permittivity measurements for strong polar liquid in the frequency range of 1 to 35 GHz, liquid crystal from 100 kHz to 1 GHz, and ionic microemulsion at frequencies between 30 MHz and 20 GHz. In each case, the necessary TDR techniques for optimal condition are given. The new TDR system (HP54120A+HP54121A) used has excellent stability compared with the earlier TDR system (HP181). It was found that, for methanol, the TDR system implemented can obtain information about the complex permittivity in the frequency range up to 25 GHz with sufficient accuracy and can possibly go up to 35 GHz using a bilinear correction. In the case of the liquid crystal, it is shown that the method is powerful not only in the microwave range but also in the radio frequency range. From the measurement of the ionic microemulsion system, it is clear that the TDR technique is applicable to the measurement of the complex permittivity of a sample with high DC conductivity.<<ETX>>

Methodes d'analyse complementaires de spectres de relaxation dielectrique obtenus par spectroscopie temporelle. I - principe et etude de quelques alcools normaux

Resume Afin detudier les spectres de relaxation dielectrique de certains alcools normaux a letat pur et sous forme de melanges binaires, les auteurs proposent de combiner le potentiel experimental des techniques de spectroscopie temporelle (S.D.T.) et la puissance de deux methodes danalyse spectrale, lune convolutive, lautre numerique, qui se sont averees complementaires. Les resultats concernant le propanol, le pentanol et le decanol a 25°C sont donnes dans cet article, alors que ceux relatifs aux melanges propanol-decanol ainsi que la discussion de synthese sont publies dans larticle suivant (II).

Methodes d'analyse complement aires de spectres de relaxation dielectrique obtenus par spectroscopie temporelle II - etude de melanges binaires propanol-decanol

Resume Le principe de la methode utilisee a ete presente dans le premier article de cette serie. Les resultats relatifs au propanol, pentanol et decanol a 25°C y ont ete donnes et discutes. Le present article est consacre aux resultats concernant des melanges binaires propanol-decanol en proportions volumiques variables et se termine par une discussion de synthese. Un mecanisme de relaxation particulier est ainsi affecte a chaque domaine de dispersion des alcools.