The Measurement of Dielectric Properties of Liquids at Microwave Frequencies Using Open-ended Coaxial Probes
نویسندگان
چکیده
Significant progress has been made in recent years in the development of microwave tomographic imaging systems for medical applications. In order to design an appropriate microwave imaging system for industrial applications, and to interpret the images produced, the materials under imaging need to be characterised. In this paper, we describe the use of open-ended coaxial probes for the measurement of dielectric properties of liquids at frequencies between 400MHz and 20GHz. The results obtained using the Misra-Blackham model for a number of liquids including water of different salinity are compared with those published in the literature showing a good agreement. For saline water, in particular, the frequency of the minimum loss depends on the salinity. It may change from 1.5GHz for the inclusion of 0.2% NaCl to 7GHz for the inclusion of 3.5% NaCl. The real part of the permittivity may also change by approximately 50% from 400MHz to 20GHz.
منابع مشابه
Radiation-Corrected Open-Ended Coax Line Technique for Dielectric Measurements of Liquids up to 20 GHz
An experimental technique and associated analysis are described for the measurement of the dielectric constants of liquids at microwave frequencies using an open-ended coax probe. The analysis includes radiative corrections to the probe-liquid interface impedance. The technique is applicable to liquid and liquidlike (e.g., biological) samples, having dielectric constants comparable to water, at...
متن کاملNondestructive and Noncontact Dielectric Measurement Methods for Transformer Oil Using Free-space Microwave Measurement System in 19 – 25 GHz Frequency Range
Nondestructive, noncontact and real time evaluation of dielectric properties of low-loss liquids are important for applications such as service-aged transformer oil, biomedical, remote sensing and design of radar absorbing material. Free-space methods were developed to measure dielectric properties of low-loss liquids at microwave frequencies. Metal-back method was developed for Freespace Micro...
متن کاملMicrowave Dielectric Measurement of Solids and Liquids over 1 to 4 Ghz Using Transmission Line Technique and Coaxial Cavity
Accurate microwave dielectric measurement of materials is necessary data for the design engineer during the development stage of electronic and communication components. Several techniques have been published in recent years for measurement of dielectric properties of materials at microwave frequencies. Each of these techniques has some limitations in terms of accuracy and frequency coverage. T...
متن کاملSome calculation methods and universal diagrams for measurement of dielectric constants using open-e - Microwaves, Antennas and Propagation, IEE Proceedings H
Several formulas for the calculation of the admittance of open-ended coaxial probes from the complex permittivity, E, of the measured medium and the dimensions of the probe are presented. The inverse problem, calculation of c from the measured admittance of the probe, is also studied in detail. These formulas are discussed and compared in terms of numerical calculations. New universal diagrams ...
متن کاملDielectric Properties of Biomass/Biochar Mixtures at Microwave Frequencies
Material dielectric properties are important for understanding their response to microwaves. Carbonaceous materials are considered good microwave absorbers and can be mixed with dry biomasses, which are otherwise low-loss materials, to improve the heating efficiency of biomass feedstocks. In this study, dielectric properties of pulverized biomass and biochar mixtures are presented from 0.5 GHz ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1999