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1 – 10 of 550The purpose of this paper is to investigate microwave reflection, transmission, and complex permittivity of p‐toluene‐2‐sulfonic acid doped conducting polypyrrole coated…
Abstract
Purpose
The purpose of this paper is to investigate microwave reflection, transmission, and complex permittivity of p‐toluene‐2‐sulfonic acid doped conducting polypyrrole coated nylon‐lycra textiles in the 1‐18 GHz frequency with a view to potential applications in the interaction of electromagnetic radiation with such coated fabrics.
Design/methodology/approach
The chemical polymerization of pyrrole is achieved by an oxidant, ferric chloride and doped with p‐toluene sulfonic acid (pTSA) to enhance the conductivity and improve stability. Permittivity of the conducting textile substrates is performed using a free space transmission method accompanied by a mathematical diffraction reduction method.
Findings
The real part of permittivity increases with polymerization time and dopant concentration, reaching a plateau at certain dopant concentration and polymerization time. The imaginary part of permittivity shows a frequency dependent change throughout the test range. All the samples have higher values of absorption than reflection. The total electromagnetic shielding effectiveness exceeds 80 percent for the highly pTSA doped samples coated for 3 h.
Originality/value
A non‐contact, non‐destructive free space method thin flexible specimens to be tested with high accuracy across large frequency range. The non‐destructive nature of the experiments enables investigation of the stability of the microwave transmission, reflection, absorption and complex permittivity values. Moreover, mathematical removal of the diffraction enables higher accuracy.
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Hakim Sadou, Tarik Hacib, Hulusi Acikgoz, Yann Le-Bihan, Olivier Meyer and Mohamed Rachid Mekideche
The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the…
Abstract
Purpose
The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the measurements of the probe admittance (Y(f) = G(f)+ jB(f )). The purpose of this paper is to develop an alternative inversion tool able to predict the evolution of the complex permittivity (ε = ε′ – jε″) on a broad band frequency (f from 1 MHz to 1.8 GHz).
Design/methodology/approach
The inverse problem is solved using adaptive network based fuzzy inference system (ANFIS) which needs the creation of a database for its learning. Unfortunately, train ANFIS using f, G and B as inputs has given unsatisfying results. Therefore, an inputs selection procedure is used to select the three optimal inputs from new inputs, created mathematically from original ones, using the Jang method.
Findings
Inversion results of measurements give, after training, in real time the complex permittivity of solid and liquid samples with a very good accuracy which prove the applicability of ANFIS to solve inverse problems in microwave characterization.
Originality/value
The originality of this paper consists on the use of ANFIS with input selection procedure based on the Jang method to solve the inverse problem where the three optimal inputs are selected from 26 new inputs created mathematically from original ones (f, G and B).
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Yoko Yamada Pittini, Dana Daneshvari, Susanne Leparoux, Sébastien Vaucher, Axel Ritter, Lukas Rohr and Hans Leuenberger
To investigate the effect of poly ethylene glycol (PEG) chain length on the dielectric properties of paraffin‐based PEG polymers (H(CH2)n–(OCH2CH2)mOH) from both experimental and…
Abstract
Purpose
To investigate the effect of poly ethylene glycol (PEG) chain length on the dielectric properties of paraffin‐based PEG polymers (H(CH2)n–(OCH2CH2)mOH) from both experimental and analytical approach.
Design/methodology/approach
Dielectric constant studies of paraffin‐based PEG polymers were carried out at temperatures above the melting point. The measurements were carried out at frequencies between 0.4 and 20 GHz. The number of PEG units, m, was varied from 0 to 80 to investigate the effect of the PEG chain length on the dielectric properties of the whole polymer.
Findings
With the existence of a dipole moment on PEG but not on pure paraffin, both the real and imaginary part of the dielectric permittivity become larger with increasing chain length of PEG. PEG 3000 showed the highest dielectric constants in the measured frequency range. The effect of the PEG chain length can be explained well by introducing the fraction of molecular weight of PEG divided by the molecular weight of the whole polymer (we call this fraction “Mw fraction of PEG”). Both, real and imaginary part of the dielectric permittivity exhibit a cubic dependence of the molecular weight fraction, and the loss tangent exhibits a linear dependence. These relationships make it possible to predict the microwave heating of the polymer in function of the PEG chain length, carbon chain length and microwave frequency.
Originality/value
For the dielectric permittivity of paraffin‐based PEG polymers, the effect of the PEG chain length, carbon chain length and applied microwave frequency on the loss tangent was explained well by introducing the molecular weight fraction of PEG.
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Kunal Kumar Singh, Santosh Kumar Mahto, Rashmi Sinha and Vishnu Priye
The purpose of this paper is to retrieve the dielectric constant of the material under test (MUT) by using an empirical relationship, which relates the dielectric properties with…
Abstract
Purpose
The purpose of this paper is to retrieve the dielectric constant of the material under test (MUT) by using an empirical relationship, which relates the dielectric properties with all three resonant frequencies of the proposed sensor. Each notch of the sensor is analyzed for sensitivity by using 15 different MUTs with relative permittivity ranging from 1.006 to 16.5 with a fixed dimension of 12 mm × 12 mm × 1.2 mm.
Design/methodology/approach
In this paper, we present a triple-notch metamaterial-based sensor for the solid dielectric characterization based on a microstrip transmission line and a direct coupled-double split ring resonator (DC-DSRR). The proposed sensor is designed, and its response is measured using a vector network analyzer to verify the concept. The shift in the resonant frequencies of the proposed sensor owing to contact with MUT is depicted as a function of permittivity using the curve fitting tool.
Findings
The proposed sensors have three notches, with the third notch being more sensitive than the first and second notch because of the high resonance frequency. For the first, second and third resonances, the proposed sensor has sensitivity ranges from 4.9% to 14.68%, 8.97% to 23.95% and 15.48% to 29.36%, respectively. The findings of the simulations, measurements and formulations are all in good accord.
Originality/value
In comparison to previous solid dielectric metamaterial sensors, the proposed triple-notch sensor based on a microstrip transmission line and DC-DSRR has the following advantages: it has a simple unit-cell structure and meets the needs of miniaturization, compact size, low cost and improved sensitivity. It determines the relative permittivity using all three notches so that the accuracy of the measurement is enhanced as compared with single- and double-notch sensors.
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Adriana Bonilla Riaño, Antonio Carlos Bannwart and Oscar M.H. Rodriguez
The purpose of this paper is to study a multiphase-flow instrumentation for film thickness measurement, especially impedance-based, not only for gas–liquid flow but also for…
Abstract
Purpose
The purpose of this paper is to study a multiphase-flow instrumentation for film thickness measurement, especially impedance-based, not only for gas–liquid flow but also for mixtures of immiscible and more viscous substances such as oil and water. Conductance and capacitive planar sensors were compared to select the most suitable option for oil – water dispersed flow.
Design/methodology/approach
A study of techniques for measurement of film thickness in oil – water pipe flow is presented. In the first part, some measurement techniques used for the investigation of multiphase flows are described, with their advantages and disadvantages. Next, examinations of conductive and capacitive techniques with planar sensors are presented.
Findings
Film thickness measurement techniques for oil–water flow are scanty in the literature. Some techniques have been used in studies of annular flow (gas–liquid and liquid–liquid flows), but applications in other flow patterns were not encountered. The methods based on conductive or capacitive measurements and planar sensor are promising solutions for measuring time-averaged film thicknesses in oil–water flows. A capacitive system may be more appropriate for oil–water flows.
Originality/value
This paper provides a review of film thickness measurements in pipes. There are many reviews on gas – liquid flow measurement but not many about liquid – liquid flow.
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T.S. Dhahi, U. Hashim and M.E. Ali
The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to…
Abstract
Purpose
The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to be used in biomolecular sensing devices.
Design/methodology/approach
The authors previously reported the fabrication and morphological characterization of these structures. In this report, they electrically probed the presence of nanogap through current measurement. The effects of electrolytes on the capacitance profiles of these structures were systematically studied with air, water and various dilutions of phosphate buffer saline.
Findings
An increment in capacitance was found with the increment in electrolyte concentration. Improvement in current flow, capacitance, permittivity, and conductivity were observed with the smaller size nanogaps, suggesting their applications in low power consuming devices.
Originality/value
Since nanogap‐based dielectric biosensing devices need to be operated with a low level of current to avoid biomolecular damage, these structures should have potential applications in dielectric‐based biomolecular detection using a low cost dielectric analyser.
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P.B. Kashid, D.C. Kulkarni, V.G. Surve and Vijaya Puri
The purpose of this paper is to study thickness dependent variation in microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films and enhancement of power…
Abstract
Purpose
The purpose of this paper is to study thickness dependent variation in microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films and enhancement of power efficiency of Ag thick film EMC patch antenna.
Design/methodology/approach
X‐band microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films were measured by superstrate technique using Ag thick film EMC patch antenna as the resonant element. The complex permittivity and permeability of these thick films were also measured by this technique. The microwave response of the EMC patch, complex permeability and permittivity of Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and Mg0.9Al0.1Zn0.8Fe1.2O4 thick films and their thickness dependency were investigated.
Findings
The XRD patterns reveal the cubic spinel crystal system was obtained for both compositions. The crystallite size obtained was 134.68 nm for Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and 155.99 nm for Mg0.9Al0.1Zn0.8Fe1.2O4 The superstrate technique has been used successfully to evaluate the complex permittivity and permeability of the ferrite thick films in the X band. The EMC patch also show thickness and composition dependent frequency agility and enhancement of power efficiency.
Originality/value
The complex permeability of MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films measured by superstrate technique is reported in this paper. The superstrate of MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films makes the Ag thick film EMC patch antenna frequency agile and power amplification is obtained.
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A. Vivek, K. Shambavi and Zachariah C. Alex
This paper aims to focus on research work related to metamaterial-based sensors for material characterization that have been developed for past ten years. A decade of research on…
Abstract
Purpose
This paper aims to focus on research work related to metamaterial-based sensors for material characterization that have been developed for past ten years. A decade of research on metamaterial for sensing application has led to the advancement of compact and improved sensors.
Design/methodology/approach
In this study, relevant research papers on metamaterial sensors for material characterization published in reputed journals during the period 2007-2018 were reviewed, particularly focusing on shape, size and nature of materials characterized. Each sensor with its design and performance parameters have been summarized and discussed here.
Findings
As metamaterial structures are excited by electromagnetic wave interaction, sensing application throughout electromagnetic spectrum is possible. Recent advancement in fabrication techniques and improvement in metamaterial structures have led to the development of compact, label free and reversible sensors with high sensitivity.
Originality/value
The paper provides useful information on the development of metamaterial sensors for material characterization.
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Zhengrong Tian and Charles Free
A review of the dielectric measurement techniques that are currently available for the characterization of thick film and LTCC materials at microwave and millimeter wave…
Abstract
A review of the dielectric measurement techniques that are currently available for the characterization of thick film and LTCC materials at microwave and millimeter wave frequencies is presented. The intention is to show the relative advantages and limitations of the various methods, and to provide some practical guide to the particular technique that is most suitable for a given type of material, for use in a particular application. In addition, a novel slit cavity resonator method is proposed to enable substrate parameters to be more easily measured, whilst retaining high measurement accuracy. Measured data on materials from a variety of manufacturers are presented to show the validity and usefulness of this method.
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Kunal Kumar Singh, Santosh Kumar Mahto and Rashmi Sinha
This paper aims to concentrate on research that has been conducted in the previous decade on metamaterial (MTM)-based sensors for material characterization, which includes solid…
Abstract
Purpose
This paper aims to concentrate on research that has been conducted in the previous decade on metamaterial (MTM)-based sensors for material characterization, which includes solid dielectrics, micro fluids and biomolecules.
Design/methodology/approach
There has been a vast advancement in sensors based on MTM since the past few decades. MTM elements provide a sensitive response to materials while having a tiny footprint, making them an appealing alternative for realizing diverse sensing devices.
Findings
Related research papers on MTM sensors published in reputable journals were reviewed in this report, with a specific emphasis on the structure, size and nature of the materials characterized. Because electromagnetic wave interaction excites MTM structures, sensing applications around the electromagnetic spectrum are possible.
Originality/value
The paper contains valuable information on MTM sensor technology for material characterization, and this study also highlights the challenges and approaches that will guide future development.
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