scholarly journals Evaluation of a Reflection Method on an Open-Ended Coaxial Line and its Use in Dielectric Measurements

10.14311/882 ◽  
2006 ◽  
Vol 46 (5) ◽  
Author(s):  
R. Zajíček ◽  
J. Vrba ◽  
K. Novotný
Keyword(s):  
Biological Tissue ◽  
Tissue Sample ◽  
Coaxial Line ◽  
Dielectric Measurement ◽  
Network Analyzer ◽  
Reflection Method ◽  
Frequency Range ◽  
Discrete Elements ◽  
Biological Substance ◽  
Coaxial Probe

This paper describes a method for determining the dielectric constant of a biological tissue. A suitable way to make a dielectric measurement that is nondestructive and noninvasive for the biological substance and broadband at the frequency range of the network analyzer is to use a reflection method on an open ended coaxial line. A coaxial probe in the frequency range of the network analyzer from 17 MHz to 2 GHz is under investigation and also a calibration technique and the behavior of discrete elements in an equivalent circuit of an open ended coaxial line. Information about the magnitude and phase of the reflection coefficient on the interface between a biological tissue sample and a measurement probe is modeled with the aid of an electromagnetic field simulator. The numerical modeling is compared with real measurements, and a comparison is presented. 

Broad Band Microwave Dielectric Measurement of Liquids with an Open-Ended Coaxial Probe

2013 ◽  
Vol 333-335 ◽  
pp. 191-198
Author(s):  
Jia Ming Shi ◽  
Quirino Balzano ◽  
Christopher C. Davis
Keyword(s):  
Dielectric Properties ◽  
Broad Band ◽  
Dielectric Measurement ◽  
Network Analyzer ◽  
Frequency Range ◽  
Probe Technique ◽  
Microwave Dielectric ◽  
Coaxial Probe

The principles of the open-ended coaxial probe technique for the measurement of permittivity are described. Measurements of dielectric properties are carried out over a frequency range from 300MHz to 50GHz, with a system comprising an Agilent E8364B network analyzer and a connected 2.2mm diameter open-ended coaxial probe. Water, methanol and salines of 0.1M, 0.2M, 0.6M are used as calibration liquids or liquids to be measured. Measured permittivities are presented and compared with those calculated from the Cole-Cole equation. It is shown that, in order to get good results, the calibration liquid should be similar to the liquid being measured in dielectric properties.

scholarly journals Effect of Open-Ended Coaxial Probe-to-Tissue Contact Pressure on Dielectric Measurements

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2060 ◽  
Author(s):  
Gertjan Maenhout ◽  
Tomislav Markovic ◽  
Ilja Ocket ◽  
Bart Nauwelaers
Keyword(s):  
Contact Pressure ◽  
Tissue Sample ◽  
Extracellular Fluid ◽  
Biological Tissues ◽  
Dielectric Measurement ◽  
Uncertainty Interval ◽  
Dielectric Data ◽  
Coaxial Probes ◽  
Coaxial Probe ◽  
Cellular Organelles

Open-ended coaxial probes are widely used to gather dielectric properties of biological tissues. Due to the lack of an agreed data acquisition protocol, several environmental conditions can cause inaccuracies when comparing dielectric data. In this work, the effect of a different measurement probe-to-tissue contact pressure was monitored in the frequency range from 0.5 to 20 GHz. Therefore, we constructed a controlled lifting platform with an integrated pressure sensor to exert a constant pressure on the tissue sample during the dielectric measurement. In the pressure range from 7.74 kPa to 77.4 kPa, we observed a linear correlation of − 0.31 ± 0.09 % and − 0.32 ± 0.14 % per kPa for, respectively, the relative real and imaginary complex permittivity. These values are statistically significant compared with the reported measurement uncertainty. Following the literature in different biology-related disciplines regarding pressure-induced variability in measurements, we hypothesize that these changes originate from squeezing out the interstitial and extracellular fluid. This process locally increases the concentration of membranes, cellular organelles, and proteins in the sensed volume. Finally, we suggest moving towards a standardized probe-to-tissue contact pressure, since the literature has already demonstrated that reprobing at the same pressure can produce repeatable data within a 1% uncertainty interval.

Use of Network Analyzer and Coaxial Probe to Determine Complex Permittivity

1990 ◽  
Vol 189 ◽  
Author(s):  
David Blackham
Keyword(s):  
Network Analysis ◽  
Complex Permittivity ◽  
Measurement Accuracy ◽  
Coaxial Line ◽  
Vector Network Analyzer ◽  
Network Analyzer ◽  
Calibration Technique ◽  
Non Destructive ◽  
Coaxial Probe

ABSTRACTA vector network analyzer combined with an open ended coaxial probe provides a way to make non-destructive measurements of complex permittivity. These measurements can be made on both solids and liquids.Many authors have done work on using an open ended coaxial line for making these measurements[1][2][3]. They have presented different techniques for modelling the coaxial probe. This paper does not focus on the area of modelling, but deals instead with the use of a vector network analyzer and coaxial probe in making measurements. To enhance measurement accuracy, the technique described adapts a calibration technique currently in use in vector network analysis.An HP 8720B vector network analyzer was used for the development and measurements presented in this paper.

Measurement of Permittivity of Ferroelectrics Using Coaxial Resonator

2011 ◽  
Vol 109 ◽  
pp. 195-198
Author(s):  
Biao Tan ◽  
Shu Bing Su
Keyword(s):  
Resonant Frequency ◽  
Numerical Method ◽  
Boundary Element ◽  
Thick Film ◽  
Coaxial Line ◽  
Experimental Results ◽  
Network Analyzer ◽  
Frequency Range ◽  
Fundamental Resonance ◽  
Coaxial Resonator

This paper presents a coaxial resonator technique applied for the measurement of the permittivity of ferroelectric thick film. A 1/4-wavelength coaxial resonator with appropriate dimensions were designed and made for measurements so that there is only TEM fundamental resonance in the interest frequency range. The permittivity may be extracted from the measured TEM fundamental resonant frequency in the resonator. The equivalent capacitance to the part between sample and open end of coaxial line is discussed, in which the boundary element numerical method was used for modeling the capacitance. The resonant frequency was measured using network analyzer and good experimental results were obtained.

scholarly journals Simulation and Experimental Study of the Near Field Probe in the Form of a Folded Dipole for Measuring Glucose Concentration

2021 ◽  
Vol 11 (12) ◽  
pp. 5415
Author(s):  
Aleksandr Gorst ◽  
Kseniya Zavyalova ◽  
Aleksandr Mironchev ◽  
Andrey Zapasnoy ◽  
Andrey Klokov
Keyword(s):  
Experimental Measurement ◽  
Glucose Concentration ◽  
Field Experiments ◽  
Near Field ◽  
Vector Network Analyzer ◽  
Human Hand ◽  
Physical Parameters ◽  
Network Analyzer ◽  
Frequency Range ◽  
Average Deviation

The article investigates the near-field probe of a special design to account for changes in glucose concentration. The probe is designed in such a way that it emits radiation in both directions from its plane. In this paper, it was proposed to modernize this design and consider the unidirectional emission of the probe in order to maximize the signal and reduce energy loss. We have done extensive research for both bidirectional and unidirectional probe designs. Numerical simulations and field experiments were carried out to determine different concentrations of glucose (0, 4, 5.3, 7.5 mmol/L). Numerical modeling of a unidirectional probe showed that the interaction of radiation generated by such a probe with a multilayer structure simulating a human hand showed a better result and high sensitivity compared to a bidirectional probe. Further, based on the simulation results, a phantom (physical model) of a human hand was recreated from layers with dielectric properties as close as possible to the properties of materials during simulation. The probe was constructed from a copper tube and matched both the geometric and physical parameters of the model. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz for the unidirectional and bidirectional probes. Further, the results of the experiment were compared with the results of numerical simulation. According to the results of multiple experiments, it was found that the average deviation between the concentrations was 2 dB for a unidirectional probe and 0.4 dB for a bidirectional probe. Thus, the sensitivity of the unidirectional probe was 1.5 dB/(mmol/L) for the bidirectional one 0.3 dB/(mmol/L). Thus, the improved design of the near-field probe can be used to record glucose concentrations.

Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites

2007 ◽  
Vol 546-549 ◽  
pp. 1661-1664
Author(s):  
Xiao Yan Wang ◽  
Fa Luo ◽  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Hong Huan Wu
Keyword(s):  
Carbon Fibers ◽  
Microwave Dielectric Properties ◽  
Xrd Analysis ◽  
Network Analyzer ◽  
Hot Press ◽  
Frequency Range ◽  
The Real ◽  
Microwave Dielectric ◽  
Hot Press Sintering ◽  
Sintering Method

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power, short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of 9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.

scholarly journals Very Low Crosstalk Measurement of Substrate Integrated Coaxial Line (SICL)

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1174
Author(s):  
Lu ◽  
Yang ◽  
Yin ◽  
Zhao ◽  
Liu
Keyword(s):  
Coplanar Waveguide ◽  
Reference Value ◽  
Coaxial Line ◽  
Calculation Formula ◽  
Frequency Range ◽  
Practical Design ◽  
Measured Frequency Range ◽  
Coaxial Lines ◽  
First Time ◽  
Better Than

When designing a microwave circuit involving substrate integrated coaxial lines (SICLs), it is important to know what real crosstalk between SICLs is. A measured crosstalk will be a good reference value in a practical design. In addition, it is also needed to compare and check the crosstalk from the simulation and calculation formula with measured results. However, it is very difficult to measure the crosstalk between SICLs because it is theoretically very low. In this study, for the first time, the crosstalk characteristics of a SICL are evaluated through experimental design and measurements. By adjusting the layout of the structures and implementing controlled experiments, interference caused by the presence of leaks and radiation at the interface and structural transitions is effectively suppressed. The experimental results show that for two parallel SICLs with a length of 30 mm and an interval of 5 mm, the isolation is greater than 80 dB for the measured frequency range of 1–8 GHz, significantly better than the results of the grounded coplanar waveguide (GCPW).

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