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Parasitic currents on the sheaths of the coaxial cables will deteriorate the performance of the antenna, so the choke structures are needed. While a-quarter-wavelength choke sheaths at VHF and UHF are very long, miniaturized ferrite-EBG composited choke structures are proposed. The ferrite refers to ferrite magnetic beads. Electromagnetic bandgap (EBG) element is consisted of multi-section metal tubes with length relatively shorter than a-quarter-wavelength. The integrated structures are formed by arranging EBG elements and beads alternately along the coaxial line. The proposed choke structures combine the wideband choke performance of the ferrite beads and the high efficiency of the EBG structures. Furthermore, due to the difficulty of the quantitative measurement of the choke structures in an open space, a measuring setup designed in a transmission line model is devised. The choking effects of the proposed structures can be characterized by the $\vert \text{S}_{21}\vert $ parameter of the measuring device, as the direction of the currents flowing on the sheaths of feeding cables are the same as that of the currents on the inner conductor of the measuring device. Meanwhile, choking bandwidth, efficiency and size of the ferrite-EBG composited choke structures are compared with that of EBG structures and beads. The influence of different numbers of the proposed structures is studied. A prototype is fabricated and measured. The overall size of the ferrite-EBG composited choke structures is $0.25\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}} \times 0.024\,\,\lambda _{\mathrm {L}}$ (415 mm $\times40$ mm $\times40$ mm) ( $\lambda _{\mathrm {L}}$ is the wavelength of the lower end of the operating frequency band). The measured choking band ( $\vert \text{S}_{21}\vert < -10$ dB) is in the region of 181–343 MHz.

A new design of band-pass filter (BPF) with variable dual notched bands characteristic is introduced for ultra-wideband (UWB) applications. The configuration of the proposed BPF contains a rectangular-ring stub loaded with parallel-coupled lines and an inverted T-shaped electromagnetic band-gap (EBG) resonator is proposed in this letter. It is designed on a Rogers 5880 substrate with properties of ε= 2.2, δ= 0.0009, and h=1 mm. The proposed BPF exhibits a wide usable fractional bandwidth from 3.1 to 10.6 GHz and two-frequency notch-bands at 5 and 8 GHz. Due to the simple configuration and excellent characteristics of the presented design with tubule dual notch function, the proposed BPF is useful to be used in UWB communication networks.

Metamaterials in microwave frequency bands have been widely explored in the development and design of antenna structures and arrays. In this paper, the so-called Yang cell have been studied. When these cells are periodically arranged on a plane, the resulting metamaterial structure shows lower band-gap frequencies than structures composed of other unit cells of the same size. The electric and magnetic fields in the first two modes of electromagnetic propagation in the unit cell have been studied. Four equivalent circuit models of the unit cell have been developed in order to easily and quickly obtain the frequency response of the metamaterial structure. These models are explained in this paper, and were validated using full-wave computational electromagnetic methods., Los metamateriales en las bandas de frecuencias de microondas han sido ampliamente explorados en el diseño de antenas y arreglos de antenas. En este trabajo se ha estudiado la celda de Yang, que cuando es dispuesta periódicamente sobre un plano, conforma una estructura metamaterial que presenta bandas prohibidas de frecuencia más bajas que otras estructuras, con una mayor eficiencia en el uso del espacio. Se han estudiado los campos eléctricos y magnéticos en los primeros dos modos de propagación electromagnética de esta celda unitaria. Se han construido cuatro modelos circuitales equivalentes de la celda unitaria para poder obtener la respuesta en función de la frecuencia de la estructura metamaterial de forma rápida, que se encuentran explicados en el trabajo. Los modelos fueron validados por simulación numérica electromagnética de onda completa.

A novel cylindrical antenna of a miniaturized printed circuitry is invented for Microwave Radiology Imaging (MRI) applications. Folded metamaterial structures based a Frequency Selective Surface (FSS) on a cylindrical profile is conducted in the design methodology. The combination of MRI systems with Ultra-Wide Band (UWB) radars for improving the functional diagnosis and imaging process has been proposed recently. Moreover, MRI systems call for a directive beam as much as narrow about 5 dBi with a fixed direction toward the broadside over the entire frequency range of interest to suit the mechanical steering principles. Therefore, a Slotted Triangular Flared (STF) patch excited with a 50 Ω exponential curved transmission line transformer centered between two matching circuit tuners is proposed. The patch structure is mounted on a Teflon substrate backed with a Partial Defected Ground (PDG) plane. An in-phase reflector array based on a cylindrical FSS is introduced to the antenna design to enhance the bandwidth and the front to back ratio. The antenna performance is examined using CST MWS commercial software package based on the Finite Integration Technique (FIT) in both Time Domain (TD) and Frequency Domain (FD) solvers. Moreover, the antenna dimensions are modified through a parametric study to arrive to the optimal performance in terms of antenna bandwidth with minimum size. The optimal antenna dimensions are realized to be 32 mm in height with a diameter of 20 mm. It is found the proposed antenna operates over the frequency range from 7.8 GHz up to 15 GHz with a bore-sight gain varies from 2 dBi up to 6 dBi. Finally, the obtained results are re-evaluated using Finite Element Method (FEM) based on HFSS formulation. An excellent matching is observed between the evaluated results from both software packages.

This paper presents a study of the interaction between mushroom-type electromagnetic bandgap (EBG) surfaces replaced the conventional electric conductor ground plane of a stripline. The proposed EBG surface has both artificial magnetic conductor (AMC) and stopband performances. Compared to the conventional stripline, the EBG as artificial ground plane exhibits bandstop behavior which unlike all-pass behavior of the conventional stripline with electric conductor ground plane. The rejected frequency range is resulted from 6.76 to 10.08 GHz (3.32 GHz), which has fractional bandwidth of 40%. Promising results give future possibilities for practical suppression noises and interferences of systems.

International audience; This work introduces a new design approach of multilayer Electromagnetic Band Gaps (EBGs) for wideband antenna isolation in a Full-Duplex transceiver. The design methodology is applied to a conventional type of EBGs in order to improve its initial performance in terms of bandwidth and size. By stacking multiple dielectric layers with integrated vias, an enhancement of the relative bandwidth of the band gap and a strong miniaturization of the unit cell is achieved. The dispersion diagrams of the proposed EBGs are studied and full-wave electromagnetic simulations are realized to validate the isolation level and the proposed lumped model of the final structures.

A dual band to wideband reconfigurable pentagon-shaped antenna with EBG unit cell is proposed. A minimal number of two EBG unit cell is deployed to realize frequency reconfigurable mechanism. By varying the state of the EBG the antenna is capable to change its dual band operation to wideband alternately. There are three cases that have been analysed, first case is the EBG incorporated antenna with ideal and second is with the active EBG. Subsequently, the third cases is the fabricated ideal EBG incorporated antenna. The dual band operation is at 1.8 GHz and 5.2 GHz while the wide band from 1.6 GHz to 2.37 GHz (770 MHz). The proposed reconfigurable antenna is suitable to be implemented for LTE (1.6 GHz), Wi-Fi (5.2 GHz), WiMAX (2.3 GHz) and cognitive radio application.

The emergence of Body Area Networks (BAN) in recent times has increased the interest of most researchers in the field of wearable antennas. Due to its widespread popularity most of the research has been done to improve the efficiency and flexibility of the wearable antennas for in-body and on-body applications. This work is the review of the recent development in the area of wearable antennas. Further the use of different textile materials has been studied and their performance has been compared with the ordinary used substrate such as FR-4 for wearable antennas. The results show that use of textile materials have not only increased the efficiency but also they are very flexible and make the antenna suitable for in-body and on- body applications such as medical and military. The properties of antennas inside human body, on human body and finally at some distance from the human body have been studied. It has been noted that as the distance between human body and antenna reduces the properties of antenna such as efficiency, directivity and gain degrade more and more. Also the resonant frequency of antenna shifts from its original position which is a very big issue and need to be rectified. For textile materials the shift in resonant frequency is not too much and also the degradation in other properties of antenna such as efficiency, directivity and gain are insignificant.

International audience; This work presents a new design approach of wideband multilayer Electromagnetic Band Gaps (EBGs) suitable for both on package antenna isolation and switching noise suppression in high speed digital circuits. Depending on thetarget applications, the design principle is implemented from two conventional types of EBGs in order to improve their initial performance. By stacking multiple dielectric layers with integrated vias in both types of EBGs, it’s possible to achieve dual band performance, to enhance the relative bandwidth of the first band gap and to miniaturize the unit cell. The dispersion diagrams of the multilayer EBGs are proposed and full-wave simulations are performed to validate the antenna isolation and noise suppression bandwidths of the final structures.

In this paper EBG structures including parallel plates of EBGs are being used to reduce the mutual coupling between the two omni-directional antennas. Here, we have chosen the Discone antennas as omni directional antennas and comparisons between uniform and non-uniform structure with conventional array of antenna is presented, and compared with the fractal structure for designing ultra wide band structure. The multi-layer EBG structure have been designed and simulated based on EBG metamaterial characteristics. Our aim is to reduce coupling or reduction of S21 to have better coupling reduction and shielding effectiveness for applying the structure as an absorber or shield and shielding bandwidth in non uniform structure is increased up to 16 GHz. © 2015 Electronics Research Institute (ERI). Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

A robust and low-profile electromagnetic band-gap (EBG) based on flexible wearable antenna covering 2.4 GHz frequency band is presented. The incorporated EBG with antenna reduces the radiation into the human body around 17 dB and decreases the impacts of frequency detuning. The overall dimension of the antenna integrated with EBG is 56 x 56 x 4 mm3 with relative impedance bandwidth of 8.3% is achieved. The proposed design has improved the gain up to 7 dBi. Specific absorption rate (SAR) assessment is also studied to certify the performance of the antenna when it is located proximity to human tissue. The flexible antenna with aforementioned performances could be chosen as a good candidate for integration into a range of wearable devices for medical application.

Aquest treball de final de màster té com a objectiu analitzar un seguit d'estructures EBG obtingudes de certs articles per veure com es comporten i com varien les seves propietats davant alguns escenaris. Les modificacions que es duen a terme són, reduir la distància entre antena i EBG, modificar el tipus d'antena, modificar les ranures de l'array EBG par cada una d'aquestes modificacions posteriorment es simulen amb el IE3D obtenint les eficiències de radiació i d'antena, les pèrdues de retorn, les impedàncies i en els casos que es creu més convenient, el corrent de l'estructura i el diagrama de radiació. Este trabajo de final de máster tiene como objetivo analizar una serie de estructuras EBG obtenidas de ciertos artículos para ver como se comportan y cómo varían sus propiedades ante algunos escenarios. Las modificaciones que se llevan a cabo son, reducir la distancia entre antena y EBG, modificar el tipo de antena, modificar las ranuras de la array EBG par cada una de estas modificaciones posteriormente se simulan con el IE3D obteniendo las eficiencias de radiación y de antena, las pérdidas de regreso, las impedancias y en los casos que se cree más conveniente, la corriente de la estructura y el diagrama de radiación. This master's final project aims to analyze EBG structures obtained from certain articles to see how they behave and how their properties vary in some scenarios. The modifications that have been made are, reduce the distance between antenna and EBG, modify the type of antenna, modify the slots of the EBG array for each of these modifications the simulate radiation efficiencies and antenna, return losses, impedances and in the cases that are most convenient, the current of the structure and the radiation diagram are obtained.

Resumen Se presenta el desarrollo de un metamaterial para estimar el índice de refracción en líquidos. El metamaterial se desarrolló insertando celdas cilíndricas en el plano de tierra de una línea microcinta, cintas estas que forman una estructura de brecha de banda electromagnética (electromagnetic bandgap, EBG). Dentro de las celdas se depositaron líquidos con índices de refracción estimados en el laboratorio. Se evaluaron los parámetros de dispersión S 21 y S 11 mediante simulaciones electromagnéticas con modelos desarrollados, y de forma experimental, con prototipos fabricados. Se analizó la variación de la frecuencia central, el ancho de banda y el nivel de pérdidas por inserción de la brecha de frecuencias generada como respuesta a la variación del índice de refracción del material depositado dentro de las celdas. Los resultados obtenidos muestran que es posible estimar el índice de refracción de materiales monitoreando la frecuencia de resonancia o el nivel de pérdidas por inserción de la brecha generada. El metamaterial desarrollado es fácil de construir y su desempeño es adecuado en el rango de las microondas. © 2019. Acad. Colomb. Cienc. Ex. Fis. Nat. Abstract We developed a metamaterial to estimate the refractive index in liquids by inserting cylindrical cells in the ground plane of a microstrip line, lines that form an electromagnetic bandgap (EBG) structure. We deposited inside the cells liquids with refractive indices estimated in the laboratory. The dispersion parameters S 21 and S 11 were evaluated by means of electromagnetic simulations with developed models and experimentally with manufactured prototypes. We analyzed the variation of center frequency, the bandwidth, and the level of losses by the variation of the refractive index of the material deposited inside the cells. Our results showed that it is possible to estimate the refractive index of materials by monitoring the resonance frequency or the level of insertion losses of the generated gap. The metamaterial developed is easy to build and its performance is adequate in the range of microwaves. © 2019. Acad. Colomb. Cienc. Ex. Fis. Nat.

ThispaperpresentsthebandwidthenhancementofatriangularmicrostrippatchantennausingEBGstructureingroundplane[1,2]for6.42GHzresonantfrequency.ThesurfacewavesmustbesuppressedtoincreasethebandwidthbyusingEBG.ByusingEBGthestopbandcharacteristicsiscreatedovercertainfrequencyandthathasbeenadaptedtosuppressthesurfacewaveandtoenhancethebandwidthoftheantennaattheresonatingfrequency.ThemaingoalofusingEBGstructuresinthismicrostripantennaistoachievebetterbandwidthandefficiencybysuppressingthesurfacewave. Keywords-EquilateralTriangularMicrostrippatchAntenna(ETMPA),Bandwidth,EBGStructure,Returnloss&ComputerSimulationTechnologyMicrowaveStudio(CSTMS).

A novel Electromagnetic Band Gap (EBG) structure based on an off-shifted periodic metasurface is presented here. This technique can be employed for packaging of electrical circuits and gap waveguide technology. The proposed structure is easy to manufacture since it only requires drilling holes in metallic plates, reducing the cost when compared to previous works based on other textured surfaces.

Modern clinical practice relies on evidence-based medicine (EBM) and evidence-based guidelines (EBGs). The critical evaluation of EBGs value is therefore an essential step to further improve clinical practice. In our opinion, correlating levels of evidence and grades of recommendation can be an easy tool to quickly display internal consistence of EBGs.

A single-layer microstrip structure with variable line width is considered in order to create, by periodic repetition, an electromagnetic bandgap structure. The width of the line is varied in such a way as to guarantee a sinusoidally modulated value of the effective dielectric constant along the longitudinal direction. By repeating periodically the structure in the orthogonal direction, a high-impedance surface is obtained. Continuous and discrete line configurations are considered, and the performances of the two-dimensional structure with respect to the uniform line case are compared

Power plane resonances are a main source of unwanted radiated emission of printed circuit boards. Several strategies to decrease the resonance amplitude or to shift or filter the resonance frequencies exist. One of them is to use Electromagnetic Band Gap and/or power isolation structures. In this paper four different power isolation concepts were evaluated. The effect of power plane, power track and power island structures on the noise reduction in printed circuit board with active components was investigated.

Material parameter characteristics of a photonic multi-band-gap structure, relying on strip-line technology, is presented. Two layers of dielectric fill the space between two metallic planes and surround a periodic 2D lattice of rectangular metallic patches connected to the ground plane through metallic vias. The variations of the dispersion diagrams with the dielectric constant of one of the layers as parameters are calculated by electromagnetic simulation. Due to the large number of band-gaps the structure presents in the microwave range, it may find applications in multifrequency filter design and enhanced sensibility sensor construction.

Today antennas appear to be a key component in radio systems. They often need new requirements such as beam tilting, multibeam, large bandwidth... In fact many structures are still bulky, mostly realized with pieces of metal supported by several insulators; only the printed antenna technology avoids this weight due to oversized pieces of metal but has limitation in bandwidth and is still planar. The technology of metallized foam developed by ADVANTEN [1] offers a new approach to the design of filar, flat and 3D antennas. Thanks to this technology new designs of antennas have been possible offering both low weight, possible shaping and development of artificial materials such as Electromagnetic Band Gap which can be electronically controlled. Various examples of antennas are presented here to illustrate some innovative developments.

Power plane resonances are a main source of unwanted radiated emission of printed circuit boards. Several strategies to decrease the resonance amplitude or to shift or filter the resonance frequencies exist. One of them is to use Electromagnetic Band Gap and/or power isolation structures. In this paper four different power isolation concepts were evaluated. The effect of power plane, power track and power island structures on the noise reduction in printed circuit board with active components was investigated.