Isabelle Huynen

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• Ph D in Applied Science
• Research Director of National Fund for Scientific Research at Catholic University of Louvain

This study investigates the combustion behavior of polycarbonate (PC) and polycarbonate–carbon nanotube (PC-CNT) composites in fluidized bed reactors. The primary objective was to evaluate the influence of carbon nanotubes (CNTs) on the thermal stability and combustion efficiency of PC. Simultaneous thermogravimetric and differential scanning calor...

Since the last decade inkjet printing (IJP) has gained much interest in the electronics field, due to its ease of fabrication and low cost, since it does not require mask fabrication and can use cheap substrates like paper, adding the advantage of recyclability. In this manuscript, a review of IJP of microwave passive devices is presented. The vari...

Polymer composites based on polylactic acid (PLA) reinforced with 0.25–5 wt.% of carbon nanotubes (CNTs) were synthesized by melt blending. The static (DC) and microwave (RF) electrical conductivity have been investigated on the PLA–CNT composites. The electrical percolation threshold has been theoretically determined using classical models of perc...

The microwave properties of carbon-based nanopowders, whether or not they are coated with magnetic nanoparticles, are characterized using a unique approach in this chapter. The microwave characterization of materials is of prime interest for several applications. Dielectric constant, electrical conductivity, and complex magnetic permeability, which...

Civilization can be shielded from the dangerous electromagnetic spectrum by using microwave absorption materials, however, absorbing electromagnetic radiation with thin thickness and high bandwidth remains a challenge, especially at scales that are significant. Herein, we propose a novel architecture where worm-like Cu 2 S particles are decorating...

The present paper aims to address the crucial concern of pollution induced by growing plastic waste and electromagnetic interference (EMI). Nanocomposites combining poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) are synthesized and compression molded into thin films. A first set of samples, referred as virgin, was kept as is, wh...

Virgin and recycled poly(lactic acid) (PLA) based nanocomposite materials were obtained and subjected to microstructural, thermal and mechanical analysis in view of fabricating efficient microwave absorbers. PLA was first exposed to artificial accelerated aging, next was mechanically recycled through grinding followed by reprocessing using melt ext...

The paper compares and optimizes through modeling conductive polymer composite slabs having different architectures of corrugated surfaces, designed to minimize both the reflectivity and its sensitivity to the angle of incidence of a microwave/millimeter wave signal impinging on the corrugated surface of the slab. Simulations using CST Studio softw...

The bi-layer absorber's microwave absorption performance can be enhanced by adjusting and manipulating the layers' composition, layer thickness, and layer arrangement. Herein, two magnetic and magneto-electric components, GdMnO3 (G) and GdMnO3-50 wt.% MoSe2 (GM), were prepared via a solvothermal method. In particular, the impact of filler loading a...

This article proposes a novel validated de-embedding approach to S-parameter measurement. This de-embedding approach benefits from the fully symmetric nature of the designed tapered transmission line test fixture and requires only a Through (THRU) standard. A key point of this approach is solving for a new coefficient $R_{x}$ , which is defined t...

In this research, we developed a wideband electromagnetic wave absorber suitable for the X-band frequency by using a unique hybrid nanocomposite structure made of FeWO4 embellished with Ag3PO4 nanopowders. Simple chemical hydrothermal and microwave-aided hydrothermal procedures were used to successfully produce single-phase spherical-like FeWO4 and...

The main parameters for achieving the optimum microwave dissipation performance in bi-layer absorbers are micromorphological characteristics, filler content composition, and layer configurations. In this research, two different doped strontium hexaferrite powders with SrFe10Al2O19 (PSrAl) and SrFe10CoTiO19 (CSrCoTi) chemical formulas were prepared...

The chapter presents a review of properties and applications of a particular category of Substrate Integrated Waveguide (SIW) named NWSIW, for NanoWire-based Substrate Integrated Waveguide. The NWSIW topology combines metallic nanowires embedded in a porous template in order to form planar compact integrated waveguides; nanowires selectively grown...

Herein, two distinct nanocomposites of CaTiO3 micro-cubes and polygonal SrFe12O19, both decorated with NiO nanoparticles, were successfully synthesized using hydrothermal method. The physico-chemical features of as-prepared samples were evaluated via XRD, FTIR, UV-vis, BET, XPS, FESEM and EDS analysis. Microwave attenuation features of as-prepared...

In this paper, an umbrella-shaped patch antenna for future millimeter-wave applications for the 5G frequency band is presented. The proposed antenna resonates at multiple frequency bands, i.e., 28 GHz, 38 GHz, and 55 GHz (V-band) that have been globally allocated for 5G communications systems. The proposed antenna is designed using Rogers RT/duroid...

Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband freque...

Carbon nanotubes (CNTs) have emerged worldwide because of their remarkable properties enlarging their field of applications. Functionalization of CNTs is a convenient strategy to tackle low dispersion and solubilization of CNTs in many solvents or polymers. It can be done by covalent or noncovalent surface functionalization that is briefly discusse...

Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoreti...

A thorough study of the parameters influencing the operation of devices based on nanowired alumina substrate is presented. The basic structures are realized by growing metallic nanowires inside alumina porous substrate. The control of the areas wherein growth occurs allows building of various microwave devices supported on the filled template. The...

This paper presents the results of a study on developing an effective technique to increase the performance characteristics of antenna arrays for sub-THz integrated circuit applications. This is essential to compensate the limited power available from sub-THz sources. Although conventional array structures can provide a solution to enhance the radi...

In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, e...

The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna’s stability. This is achieved by using the negative reactance of the N...

Polycarbonate—carbon nanotube (PC-CNT) conductive composites containing CNT concentration covering 0.25–4.5 wt.% were prepared by melt blending extrusion. The alternating current (AC) conductivity of the composites has been investigated. The percolation threshold of the PC-CNT composites was theoretically determined using the classical theory of pe...

In this paper, a set of singular integral formulations are derived to calculate the surface impedance matrix on the antenna array elements. The proposed mathematical model enables electrodynamic analysis of antenna arrays designed using metamaterial-inspired structures. The formulations allow the determination of the array's impedance, spatial and...

The present study focuses on the design of single and double layer microwave absorbers based on [email protected] metal−organic framework incorporated with MWCNTs. [email protected] metal−organic framework (MOF) and MWCNTs decorated with MOF (MW/MOF) were successfully synthesized via hydrothermal method and characterized with XRD, VSM and FESEM. Th...

This paper investigates the nonlinear properties of graphene nanoplatelets (GNPs), decorated with Fe3O4 magnetic nanoparticles (MaNPs). Nanocomposite MaNP/GNP samples were prepared by a solvothermal method with three different MaNP loading concentrations of 17 wt%, 28 wt% and 40 wt%, and deposited on a metallic interdigitated electrode (IDE). Three...

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming c...

In front of electromagnetic (EM) pollution of the environment, EM protection requires more and more efficient solutions. Multilayered films consisting of alternating stacked nickel nanowires (NWs)-based conductive layers separated by bulk polycarbonate films were fabricated as thin electromagnetic shield. The well-defined periodic arrangement of th...

This paper presents two methods for the efficient evaluation of the power balance in circular metasurface (MTS) antennas implementing arbitrary modulated surface impedances on a grounded dielectric slab. Both methods assume the surface current in the homogenized MTS to be known. The first technique relies on the surface current expansion with Fouri...

This paper presents a study of a planar antenna-array inspired by the metamaterial concept where the resonant elements have sub-wavelength dimensions for application in microwave medical imaging systems for detecting tumors in biological tissues. The proposed antenna consists of square-shaped concentric-rings which are connected to a central patch...

The current research reports the preparation of a microwave absorber containing CoFe2O4/NiFe2O4/Carbon fiber (H/S/CF) coated with polypyrrole polymer (PPy@H/S/CF) through sol-gel and in-situ polymerization processes. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), and a vector netwo...

Electronic devices that transmit, distribute, or utilize electrical energy create electromagnetic interference (EMI) that can lead to malfunctioning and degradation of electronic devices. EMI shielding materials block the unwanted electromagnetic waves from reaching the target material. EMI issues can be solved by using a new family of building blo...

In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (ε < 0) and negative permeability (µ < 0) have unique properties that do not occ...

Because electromagnetic (EM) pollution of the environment is becoming such a pervasive issue, highly efficient solutions for EM protection are being keenly sought for. Our approach provides new avenues to simple, compact, and efficient broadband microwave absorbers designed to cancel EM interferences in the microwave range. The paper demonstrates t...

This is a reprint of articles from the Special Issue published online in the open access journal Micromachines (ISSN 2072-666X) (available at: https://www.mdpi.com Special Issue Editor : Isabelle Huynen

Initially inspired by the work of Richard Feynman in 1959 during his famous talk “There is plenty of room at the bottom”, nanoscience and nanotechnology have moved during the 2000s from laboratory developments to daily life applications [...]

Multibeam and beam scanning capabilities of modulated metasurface (MTS) antennas using multiple feeds are investigated. The MTS synthesis is performed by direct inversion of an Electric Field Integral Equation (EFIE) obtained after expanding the unknown equivalent impedance profile into Fourier-Bessel Basis Functions. Two approaches are explored. T...

Two types of nanocomposites based on multiwalled carbon nanotubes (MWCNTs) decorated with metallic nickel nanoparticles (NiNPs) possessing very different size distributions (13 vs. 130 nm) were produced using novel synthetic techniques. The obtained nanocomposites were dispersed in a polycarbonate (PC) matrix to produce thin (~500 μm) composite fil...

Featured Application The widespread issue of electromagnetic (EM) pollution demands ever more efficient solutions for the protection of people and equipment. Our approach provides simple and efficient methods for the fabrication of compact shielding materials preventing electromagnetic interference, in particular structures offering broadband micro...

A microwave absorber combining frequency-selective surfaces (FSSs) and dielectric layers is presented. FSSs are printed on dielectric layers using a resistive ink made of a suspension of carbon nanotubes. The absorber exhibits a fractional bandwidth of 137%, corresponding to reflectivity lower than -15 dB and absorption higher than 90% from 7.30 ti...

We present and discuss the synthesis of modulated metasurface (MTS) antennas capable of radiating multiple beams at multiple frequencies. The proposed technique is built on a recently developed Integral Equation formalism. Assuming that the MTS can be homogenized over the whole frequency band, the sheet impedance describing the MTS can be accuratel...

Absorption in excess of 90% is induced over a 22 GHz bandwidth by the combination of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) dispersed in a polymer matrix. This performance is achieved by a stack of polymer films showing a concentration gradient of mixed CNTs and GNPs from layer to layer, having a total thickness of only 0.76λ/4.\...

Intelligence technologies aim at providing sense organs to machines such as artificial nose or tongue. Inspired by chemically-sensitive devices and antenna couplers, the Insulated Substrate Impedance Transducer (ISIT) reacts to neighboring electro-active targets by changes in its built-in properties, measured through interface electrodes. Exhaustiv...

Supplementary material to the article "Highly Efficient Wideband Microwave Absorbers Based on Zero-Valent Fe@γ-Fe 2 O 3 and Fe/Co/Ni Carbon-Protected Alloy Nanoparticles Supported on Reduced Graphene Oxide"

Electronic systems and telecommunication devices based on low-power microwaves, ranging from 2 to 40 GHz, have massively developed in the last decades. Their extensive use has contributed to the emergence of diverse electromagnetic interference (EMI) phenomena. Consequently, EMI shielding has become a ubiquitous necessity and, in certain countries,...

This paper compares two laser-assisted processes developed by the authors for the fabrication of microwave devices based on nanowire arrays loaded inside porous alumina templates. Pros and cons of each process are discussed in terms of accuracy, reproducibility and ease of fabrication. A comparison with lithography technique is also provided. The e...

A full-wave synthesis algorithm for modulated meta-surface antennas is presented. It is able to provide arbitrary radiation patterns, with any polarization. The algorithm does not use the local periodicity approximation, but is directly based on the electric field integral equation (EFIE). Using Fourier-Bessel basis functions (FBBFs), one can effic...

A ultra-wideband microwave absorber (UWMA) combining frequency-selective surfaces (FSS) and dielectric layers is proposed. FSS patterns are printed by inkjet on dielectric layers using a resistive magnetic ink made of suspended carbon nanotubes decorated with \({\text {Fe}}_3{\text {O}}_4\) nanoparticles. The UWMA exhibits a huge fractional bandwid...

A ultra-wideband microwave absorber (UWMA) combining Frequency-Selective-Surfaces (FSS) and dielectric layers is proposed. FSS patterns are printed by inkjet on dielectric layers using a resistive magnetic ink made of suspended carbon nanotubes decorated with F e 3 O 4 nanoparticles. The UWMA exhibits a huge fractional bandwidth of 140%, correspond...

This paper presents a novel approach for the characterization of microwave properties of carbon-based nanopowders, decorated or not with magnetic nanoparticles. Their microwave parameters, dielectric constant, electrical conductivity, and complex magnetic permeability are extracted from measurements performed using a single transmission line acting...

A family of orthogonal, and entire-domain basis functions (named Fourier-Bessel) is proposed for the analysis of circular modulated metasurface (MTS) antennas. In the structures at hand, the MTS is accounted for in the Electric Field Integral Equation (EFIE) as a sheet transition impedance boundary condition (IBC) on top of a grounded dielectric sl...

A method based on the Electric field integral equation (EFIE) is proposed for synthesizing planar metasurface antennas built on elliptical apertures. The metasurface is modeled with a modulated tensorial surface impedance. Entire-domain basis functions are used to discretize efficiently the currents as well as the surface impedance, allowing a quas...

A new approach is presented for synthesizing modulated metasurface antennas with arbitrary radiation patterns, assumed to be given in amplitude, phase and polarization. The metasurface (MTS) is defined on a circular domain and is represented as a continuous sheet transition impedance boundary condition (IBC) on top of a grounded substrate. The prop...

An approach based on Method-of-Moment and using a set of stretched Fourier-Bessel basis functions (FBBFs) is presented for the analysis of elliptical domain metasurfaces (MTSs). This shape is preferred to the traditional circular domain, when a better control of the aperture efficiency is required. The proposed formulation makes use of a harmonic d...

This paper presents a broadband characterization method for nanocomposite powders made of magnetic nanoparticles grafted on graphene oxide sheets. A coplanar waveguide design is proposed as test cell for the nanopowders and a broadband microwave characterization of dielectric constant, conductivity, and permeability is performed even in presence of...

We present an ultrathin and flexible microwave broadband polarization transformer concept based on oriented carbon nanotubes dispersed in a polycarbonate matrix. Stacking anisotropic composite films with a controlled angle mismatch between successive layers produces a twist polarizer able to change the orientation of the electric field over broad f...

In this paper, we present a ultra-wideband radar absorbing structure operating in 5-50GHz frequency range. Two layer of Frequency Selective Surfaces (FSS) separated by dielectric spacer and having 160 Ω/sq. and 80 Ω/sq. respectively are printed on flexible PC-sheet with home-made water-based MWCNT-ink. For a thickness of 5mm a measured reflection c...

We study the influence of melt annealing and the presence of a block copolymer compatibilizer on the electrical properties of polypropylene carbon nanotubes (CNT) nanocomposites from the DC limit to microwave frequencies and link it to the morphological details. We show that the compatibilizer concentration controls three types of morphologies: sep...

We present a thin and flexible broadband polarizer-absorber concept based on a multi-layered anisotropic arrangement of carbon nanotubes (CNT) and polymer films. The anisotropic layers consist of CNT striplines deposited over a prepared polycarbonate surface. Stacks of the patterned composites organized in gradient of layer conductivity are very ef...

The hybrid concept of utilizing frequency selective surface (FSS) and polymer nanocomposite (PNC) for absorption modulation is presented in 8–18 GHz frequency band. The extruded PNCs are fabricated by incorporating different weight% fraction of conductive fillers, namely carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), in high, low and mi...

Using arrays of bistable magnetic nanowires, we show that their microwave absorption properties can be reversibly configured using low magnetic field cycling by virtue of the double ferromagnetic resonance absorption spectra. These characteristics lead to a single bifunction microwave filter that can be configured to work as a bandstop or a bandpas...

We present a multilayered invisibility cloak effective at microwave frequencies based on carbon nanotubes (CNT) and polymer foam. The structure deflects transverse magnetic (TM) waves at 6GHz to reconstruct the incoming wave front beyond an obstacle. This is achieved with the help of nested cylindrical arrangements of anisotropic conductive films a...

This paper presents a thorough study of the behaviour of microwave absorption occurring in lossy dielectric slabs as used for microwave absorbers. The influence of the various parameters governing absorption is demonstrated : dielectric constant, conductivity, thickness of slab and frequency. It is shown that for several combinations of values for...

An experimental process for the fabrication of microwave devices made of nanowire arrays embedded in a dielectric template is presented. A pulse laser process is used to produce a patterned surface mask on alumina templates, defining precisely the wire growing areas during electroplating. This technique makes it possible to finely position multiple...

We demonstrate experimentally and numerically that a bilayer triangular-shaped chiral metamaterial (TCMM) gives a nearly perfect cross-polarization with 90% polarization conversion efficiency reported at X-band regime. The giant optical activity in the proposed TCMM arises due to the strong cross-coupling between the electric and magnetic dipole as...

Three methods for decoration of nanocarbon solids (NcS) with magnetite nanoparticles (MaNPs) were compared, namely covalent linkage, direct co-precipitation or solvothermal synthesis. The influence of each method on the obtained nanocomposites most relevant characteristics were studied, such as chemical identity, size, loading rate and spatial dist...

This paper presents an approach for electromagnetic shielding by absorption based on polycarbonate films containing oriented carbon nanotubes. Films with and without in plane CNT orientation were obtained by squeezing nanocomposites in the melt. The results reveal that the thick non-oriented and thin oriented nanocomposites have comparable highest...

The NANO4WAVES approach aims at investigating and demonstrating the potential of a clever hierarchization into polymer matrices of nanoscaled inclusions (carbon nanotubes, graphene, metallic nanotubes and nanospheres) for controlling signals, with a dramatic impact on the electromagnetic propagation at wavelengths ranging from micrometers up to ten...

Back Cover: Electrically conductive polymeric foams of polypropylene and carbon nanotubes are prepared using supercritical carbon dioxide technology. Cell nucleation occurs when the high saturation pressure is rapidly released at a temperature higher than the glass transition temperature. Green conductive polymeric foam is effective at absorbing el...

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO2) technology. The foaming parameters (temperature, pressure) are investigated to establish their influence on the morphology of the resulting foams and their impact on the electrical conductivity. As promising elect...