Xavier Begaud

• Professor
• Professor (Full) at LTCI, Telecom Paris, Institut Polytechnique de Paris

In this contribution, a single-layer metasurface absorber is proposed for collecting the ambient radio frequency energy at 2.45 GHz. A design methodology is proposed to optimize the finite array performance. An absorber of 4×5 cells is designed and simulated to demonstrate that this methodology enables an improvement of the capturing efficiency fro...

This paper analyzes the frequency-dependent electromagnetic characteristics of usual building materials such as mortar, glass or wood. Reflection and transmission losses are measured from 2 to 260 GHz and the related permittivity and conductivity are estimated. Results are compared with the ITU-R 2040-3 model that is mainly defined for frequency be...

Dans cette communication, nous avons associé un élément rayonnant large bande à deux métasurfaces pour obtenir une antenne multibande et large bande. Les diagrammes de rayonnement dans quelques bandes de la 4G et du Wi-Fi 2.4/5/6E (2.40–2.70 GHz, 5.17–5.83 GHz et 5.93–6.45 GHz) sont directifs et le faisceau peut être dynamiquement dépointé jusqu’à...

Dans cet article, nous estimons les caractéristiques électromagnétiques (permittivité et conductivité) des matériaux de construction usuels, supposés à faibles pertes, en fonction de la fréquence et à partir de la mesure du facteur de réflexion et de transmission dans la bande 2-260 GHz. Les résultats sont comparés au modèle ITU (Union Internationa...

The paper deals with the design, realization and measurement of a lightweight electromagnetic metamaterial absorber for space applications operating on the [2 GHz, 2.3 GHz] frequency band, under oblique incidence from 35° to 65°.

We present a compact antenna with stable, unidirectional, high-gain radiation patterns to cover the standards 5G/4G/Wi-Fi 2.4/5/6E and X-band communications. The operating frequency bands are 2.4–2.7, 3.4–3.8, 5.17–6.45, and 8.0–12.0 GHz. The thickness is 0.09λ_l and the aperture size is 0.51×0.65 λ_l^2, where λ_l is the wavelength at the lowest fr...

Metasurfaces are artificial materials that can provide properties not readily available in nature for the interaction with acoustic, elastodynamic, or electromagnetic waves. In Electromagnetics, metasurfaces allow particular functionalities to antennas, which in turn lately have been increasingly pushed to a multiband operation. To fully exploit me...

This work presents the design and realization of four linear arrays of microstrip rectangular patch antennas. This linear array is one of the elements of a passive radar using signals from 4G base stations for UAV detection. The arrays have been validated and operate from 2.62 GHz to 2.69 GHz, with a HPBW of 82° in H-plane and a maximal gain going...

When a wideband antenna is backed by an artificial magnetic conductor (AMC) reflector, the bandwidth is reduced. With the optimization of the shape of the AMC it is possible to exhibit multiband behavior, but the problem becomes complex if the bands are also intended to be wide. In this study, a methodology that exploits both the expected in-band a...

The sixth-generation wireless communication research activities were launched worldwide. A tendency of some researchers to use the sub-terahertz frequency band for 6G is noticed. This frequency band is selected as a candidate for 6G due to its remarkable wide unused frequency bandwidth. In this paper, typical indoor environment material transmissio...

In this work, we present the design of a tri-band artificial magnetic conductor (AMC) as a quad-band reflector for the 5G, 4G, Wi-Fi and X-band communications. To show the interest of the solution, the AMC is placed under an Archimedean spiral at a distance close to a quarter-wavelength in the X band, which implies a smaller electrical distance for...

The simple planar shape and wideband input impedance of the bow‐tie antenna make it suitable to diverse wideband applications. However, the radiation pattern of this kind of antenna is not stable and the gain in the broadside direction deteriorates with increasing frequencies. In this article, the operation of both the triangular and the rounded‐ed...

Les métasurfaces de Huygens sont des outils puissants pour façonner les fronts d'ondes électromagnétiques. Dans ce travail, nous présentons une cellule multibande et reconfigurable d’une métasurface de Huygens qui permet le dépointage du faisceau dans la bande 5G (3.4-3.8 GHz) sans perturber la phase et la transmission dans les bandes 4G (2.5–2.7 G...

In this communication, we present the results obtained within the framework of the Astrid project (DGA-ANR) SAFAS (Self-complementary Surface with Low Signature). The antenna has been designed and optimized using an analytical model of the complete structure. The antenna is able to maintain frequency bandwidth ratios of 4.6: 1 for a scanning capabi...

Le déploiement des réseaux mobiles de cinquième génération (5G) apporte son lot d’innovations en termes de technologies d’antennes. Il serait trop ambitieux de lister toutes leurs spécificités et cet article se focalisera (comme les nouvelles antennes 5G) sur quelques solutions remarquables pour les smartphones et les points d’accès radio.

Cette contribution présente la conception d’un réseau linéaire d’antennes patch microruban avec un diagramme en élévation cosécanté. Ce réseau linaire est un des éléments d’un radar passif utilisant les signaux des stations de base 4G pour la détection de drones. Le réseau a été conçu pour opérer entre 2.62 GHz à 2.69 GHz. Après conception et simul...

Featured Application A low-mass wide-angle electromagnetic absorber was designed in order to reduce interference problems arising on satellite platforms. Abstract This article presents the design, realization and measurement of lightweight absorbing material for space applications. The electromagnetic absorber, operating on the [2 GHz, 2.3 GHz] fr...

Recently the performances of radar absorbing materials have been extended by designing new thin structures with wideband properties and large angles of incidence. In this paper, the design and performances of such ultrawideband microwave absorber of low thickness material developed within the framework of the SAFAS project (self-complementary surfa...

The H2020 TWEETHER project has produced the first ever point to multipoint wireless network at W-band (92 -95 GHz). The field trial of TWEETHER system was conducted in the campus of the Polytechnic University of Valencia (Spain). A campus-wide Gigabit Ethernet network interconnecting four different sites was deployed to provide round-the-clock out-...

Using structural composite materials for the fabrication of Radar Absorbing Materials (RAM) allows combining the strong load bearing capability with the radar absorbing functionality in a unique structure. This article shows the possibility to transpose an already existing metamaterial absorber to the domain of composite materials. The dielectric l...

In order to extend the performance of radar absorbing materials, it is necessary to design new structures with wideband properties and large angles of incidence which are also as thin as possible. The objective of this work, realized within the framework of the SAFAS project (self-complementary surface with low signature) is, then, the development...

This article presents the results of a design of a forward to backward leaky wave antenna (LWA) based on rectangular waveguide (RWG) technology. This structure combines a snaky waveguide with slots to achieve the required radiation characteristics. The effect of increasing the number of snaky cells has been analyzed to study the effect on the radia...

In the field of circular-polarized planar wire antennas for very wide band telecommunications systems, and an antenna reflector for such an antenna, an antenna device comprises an antenna reflector and an antenna, and a method for implementing the antenna reflector. The antenna reflector comprises, on the one hand, a first reflection region exhibit...

Transformation Optics (TO) based superstrates allow modifying radiation patterns of antennas but generally required anisotropic magnetic and dielectric materials or metamaterials. Previously, we presented a TO-based all dielectric solution which allows achieving in-plane radiation from planar antennas. In this paper, we will present the approach t...

Une nouvelle méthode de calibration des antennes actives qui prend en compte les effets de bord et de couplage entre les éléments rayonnants est présentée dans cette communication. Le champ lointain est calculé par Matlab à partir des données du champ proche calculé par HFSS. Ensuite par rétro-propagation des données de champ lointain on calcule l’...

Cet article présente la réalisation et la mesure d’un superstrat tout diélectrique inspiré de la transformation d’espace, fonctionnant en bande-L et fabriqué à l’aide de l’impression 3D. Le dispositif obtenu permet de transformer radicalement le rayonnement directif d’une antenne patch en un rayonnement antipodal ayant deux lobes dans le plan azimu...

Nous présentons dans cet article la seconde phase du projet SAFAS (Surface Auto-complémentaire à FAible Signature) portant sur la conception d’un absorbant à très large bande et conservant ses propriétés jusqu’à des incidences de 60° quelle que soit la polarisation et de faible épaisseur. Une première série de résultats relative à l’absorbant théor...

A new calibration method of active phased array antennas is presented in this paper. This method can be applied to the antenna arrays of various sizes and various radiating element numbers. It takes into account the edge effects and the coupling between the radiating elements. This method allows avoiding the degradations of the antenna radiation pa...

Nowadays, the increasing demand for capacity in telecommunication systems forces cellular network operators to develop new backhaul solutions. The millimeter wave band technology is one of the most promising solutions to support the increasing flux of data and to replace long deployment time and cost of optical fiber. Thus, the goal of the H2020 TW...

In this article, a dielectric superstrate inspired from transformation optics is presented. When placed over a patch antenna, this superstrate increases the half power beam width (HPBW) of a classical patch antenna. An appropriate spatial transformation relation with spatial compression and refractive index shift factors has been used to derive an...

In this article, a wideband dual polarized self-complementary connected array antenna with low Radar Cross Section (RCS) under normal and oblique incidence is presented. First, an analytical model of the multi-layer structure is proposed in order to obtain a fast and reliable pre-dimensioning tool providing an optimized design of the infinite array...

The European Horizon 2020 project TWEETHER aims to make a breakthrough in wireless networks to overcome the congestion of the actual mobile networks and foster the new 5G networks. A European Consortium including four universities and five companies from four European countries is devoting a relevant effort to realize novel terminals and transmissi...

Various applications require an antenna to provide coverage in the azimuthal plane while still retaining a low profile. Transformation Optics method can be used to provide novel solutions to fulfill this objective. In this paper, the design of dielectric superstrate inspired from Transformation Optics has been reported which completely reorients th...

A superstrate to modify the radiation pattern of a patch antenna designed using transformation optics method is presented. At first, the transformation relations between the physical and virtual space are described. Then, material parameters calculated from transformation optics method are used to design a three dimensional low profile superstrate...

This paper studies the effect of a hybrid reflector on the radiation pattern of an ultra-wide band diamond dipole antenna. The cause of a split radiation pattern in the broadside direction appearing when using a uniform Artificial Magnetic Conductor (AMC) based reflector is investigated and is found to be due to destructive interference in broadsid...

The aim of the present contribution is to show that metasurfaces such as reactive impedance surfaces (RIS) and artificial magnetic conductors can be efficiently used in the design of low-profile circularly polarized L-band antennas. We present the design and simulation of the compact and low-profile antennas. The solution based on RIS will be compa...

This work presents a terminal mobile model where an Inverted-F Antenna (IFA) is associated with three different kinds of metamaterials: artificial magnetic conductor (AMC), electromagnetic band gap (EBG) and resistive high-impedance surface (RHIS). The objective was to evaluate whether some metamaterials may be used to reduce exposure while preserv...

This deliverable D4.3 presents the final absolute exposure index evaluation. It completes the 5-steps common exposure evaluation methodology for each of the WP4 studied solutions. The consolidated results on components and radio link techniques are shown. WP4 analyses and conclusions are delivered and notably attempt to position these different sol...

Cet article présente la conception d’un superstrat à l’aide de la Transformation d’Espace (TE) pour modifier le rayonnement directif d’une antenne patch afin d’obtenir un rayonnement dans le plan azimutal. Ensuite, on analyse le rôle des paramètres constitutifs du superstrat sur le rayonnement désiré.

Compact and directive ultra-wideband antennas are required in variety of applications. Directional wideband antennas can be designed by using a reflector to redirect the energy back in half space and increase the gain. Use of artificial magnetic conductors (AMC) as reflectors for antennas allows reduction in the thickness of an antenna using tradi...

This paper presents a simplified model of a terminal mobile where a monopole antenna is associated with three different metamaterials: artificial magnetic conductor (AMC), electromagnetic band gap and resistive high-impedance surface (RHIS). The objective is to evaluate what is the metamaterial which is the best solution to reduce exposure. The exp...

The invention relates to a device (1) for absorbing electromagnetic waves, comprising a plurality of arrays (Ei) each comprising at least one cell (2) for absorbing electromagnetic waves, characterised in that: each array (Ei) has a minimum absorption coefficient valid for given parameters of the waves incident on said array (Ei), said parameters c...

This paper presents a terminal mobile model where an Inverted F Antenna (IFA) is associated with three different metamaterials: Artificial Magnetic Conductor (AMC), Electromagnetic Band-Gap (EBG) and Resisti- ve High Impedance Surface (RHIS). The objective is to evaluate what is the metamaterial which is the best solution to reduce exposure. The exp...

We present in this work a comprehensive analytical model of a self-complementary connected array antenna. This circuit model is used to dimension and optimize the structure with a minimum computational burden. The final design involves a meta-surface on top of the radiating aperture, together with a substrate made from an artificial anisotropic d...

The aim of the present contribution is to show that metasurfaces like Reactive Impedance Surfaces (RIS) and Artificial Magnetic Conductors (AMC) can be efficiently used in the design of low-profile circularly-polarized L-band antennas. We present the design, simulation and characterization of the compact and low-profile antennas. In order to prove...

L’objectif de ce travail est de montrer qu’il est possible de modifier considérablement le diagramme de rayonnement d’une antenne patch fonctionnant dans les bandes L5 et L2 du GPS à l’aide d’un superstrat particulier. Le superstrat est obtenu en utilisant la technique de la Transformation d’Espace (TE) et permet de changer un diagramme de rayonnem...

Dans cette communication, une méthode pour corriger les défauts d’amplitude et de phase dans les réseaux d’antenne causés par les effets de bord et de couplage entre les éléments rayonnants est présentée. La méthode est inspirée d’un procédé de mesure d’antenne en champ proche. Un modèle numérique (MATLAB) permet de calculer le champ lointain à pa...

Cet article présente les performances d’une antenne IFA (Inverted F Antenna) localisée à différents emplacements sur un modèle simplifié de smartphone et en présence de trois structures à base de métamatériaux: un Conducteur Magnétique Artificiel (CMA), un matériau à Bande Interdite Electromagnétique (BIE) et une Surface Haute Impédance Résistive...

Cet article présente une antenne large bande, de faible épaisseur et directive grâce à un réflecteur hybride issu de la modification d’un conducteur magnétique artificiel. La bande passante de l’antenne finale est 63% [4.2-8.1 GHz]. Ce réflecteur permet de conserver un gain dans l’axe supérieur à 4.2 dB sur une bande de 46% [4.2-6.7 GHz] dans la...

Nous présentons les résultats obtenus dans le cadre du projet SAFAS (Surface Auto-complémentaire à FAible Signature) portant sur la conception d’une antenne réseau connectée auto-complémentaire. Un modèle analytique robuste a été développé permettant l’optimisation du réseau pour atteindre des rapports de bande de l’ordre de 5 :1 pour des dépointag...

In this paper, a wideband dual polarized Coplanar Waveguide (CPW) fed antenna integrating a wide stop-band filter is presented. The designed filter is based on a non-uniform Defected Ground Structure (DGS) in order to obtain a wide stop-band and a compact size. This filter is used to reject harmonics and spurious radiation arising from the R.F fron...

In this paper, a structure composed by a wideband dual polarized antenna, a filter for harmonic suppression, a matching circuit and a band-notch filter, is presented. This complete structure is called a versatile intricate antenna because, on one hand, functions that are typically outside the antenna have been integrated into the radiating part, an...

Based on a common evaluation 5-step methodology, initial performance assessments of the innovative solutions considered within WP4 are carried out. A dozen of radio components and transmission techniques solutions are developed and evaluated through ratio of the Exposure Index. The proposed intermediate performances assessments show a large range o...

We present the first part of a study supported by the French Ministry of Defense, entitled SAFAS, which aims at developing a low profile self-complementary radiating surface with low signature. This surface concept is intended to be used for antenna and absorber designs. We show some preliminary results for an antenna array required to work for inc...

A compact wideband antenna place above a non-uniform artificial magnetic conductor (AMC) is presented. The antenna is composed of a wideband coplanar waveguide fed antenna, with wideband harmonic suppression characteristic using non-uniform defected ground structure. Besides, a non-uniform wideband AMC is designed. The AMC unit cell is composed of...

This paper aimed to show the design and performances of a flat superstrate placed above an L-band patch antenna. Obtained from the Transformation Electromagnetics technique, this superstrate enables to produce an antipodal radiation with a quasi-null radiation in the broadside direction. From the analytical transformations used for the calculation o...

This paper presents a lightweight microwave absorber suitable for space applications. The absorber is based on a resistive high-impedance surface (RHIS) optimized to achieve reflection under −15 dB in the band (2–2.3 GHz) at oblique incidence for transverse electric (TE) and transverse magnetic (TM) polarizations. A first classical isotropic RHIS s...

This paper presents a thin lightweight microwave absorber suitable for space applications. The absorber is based on Resistive High Impedance Surface (RHIS) optimized to achieve reflection under -15dB in the band [2-2.3GHz] at normal and oblique incidences for Transverse Electric (TE) and Transverse Magnetic (TM) polarizations.

A compact wideband antenna above a non-uniform Artificial Magnetic Conductor (AMC) is presented. The antenna is composed of a bowtie Coplanar Waveguide fed antenna, with wideband harmonic suppression using non-uniform Defected Ground Structure. Besides, a non-uniform wideband Artificial Magnetic Conductor is designed.

This paper aims to show the design and performances of a flat superstrate placed above an L-band patch antenna. Obtained from the Transformation Electromagnetics technique, this superstrate enables to produce an antipodal radiation with a quasi null radiation in the broadside direction. From analytical transformations used for the calculation of the...

This paper presents an analytical model to design a self-complementary connected antenna array above artificial materials like high impedance surfaces (HIS). The objective of this model is to perform parametric studies to facilitate deeper understanding of a complex antenna array with a significantly shorter computation time than with electromagnet...

This paper presents the design, realization and measurement of a thin lightweight absorbing material for space applications. Absorber design is based on high impedance surfaces loaded with resistors and known as a resistive high impedance surface (RHIS). The behavior of RHIS is analyzed at normal and oblique incidences for TE and TM polarizations....

A methodology is introduced for designing wideband, compact and ultra-thin high impedance surfaces (HIS). A parametric study is carried out to examine the effect of the periodicity on the electromagnetic properties of an HIS. This approach allows designers to reach the best trade-off for HIS performances.