A. Tajmouati - Academia.edu (original) (raw)

Papers by A. Tajmouati

Conditions Optimales De Mesure De La Diffusivite Thermique Par La Technique Des Boites

Pour des raisons de correction et d'ajustement des resultats experimentaux nous avons procede... more Pour des raisons de correction et d'ajustement des resultats experimentaux nous avons procede a une verification experimentale de l'influence de plusieurs parametres sur la mesure de la diffusivite thermique par la methode flash. En effet la technique classique n'est pas efficace pour certains echantillons. Par exemple, dans le cas ou ils seraient transparents, trop poreux et/ou leur reflexivite est trop importante, nous remedions a cela en teintons les deux faces des echantillons par une peinture noire puis nous etudions les caracteristiques thermiques de celle-ci et son effet sur la mesure de la diffusivite. Dans le cas ou le temps de reponse de l'echantillon serait comparable a celui de la source, nous cherchons l'epaisseur limite de l'echantillon a partir de laquelle la mesure pourra s'effectuer.

TELKOMNIKA (Telecommunication Computing Electronics and Control)

The requirement for applications operating at a variety of frequencies in a unified wireless devi... more The requirement for applications operating at a variety of frequencies in a unified wireless device has greatly enhanced in recent years. For this purpose, multi-functional wireless components are essential. This paper presents a new design of a wideband circularly-polarized microstrip antenna array with defected ground structure (DGS). A previous design was introduced which cover the C-band at 5.8 GHz and operates in the industrial scientific medical (ISM) band for wireless communication applications. The proposed antenna has excellent performances which include good input impedance matching with a fed of the circular polarization at 5.8 GHz. The proposed design is validated and optimized by adding a new design of defected ground structure. This aperture geometry enables the antenna to operate in a wideband. The obtained results show that the modified antenna has a good performance in terms of return loss, bandwidth, gain and radiation pattern and demonstrate that the proposed antenna offers a good solution for multi-standard wireless communication applications.

Indonesian Journal of Electrical Engineering and Computer Science

In this paper, a novel compact band pass filter (BPF) is proposed for global positioning system (... more In this paper, a novel compact band pass filter (BPF) is proposed for global positioning system (GPS) applications. The proposed filter which is based on a microstrip resonator is mounted on a low cost RO4000 substrate with a dielectric constant εr=3.5, a thickness h=1.542 mm, a loss tangent tan (δ)=0.0027. It has a bandwidth from 1.55 GHz to 1.72 GHz. This filter is optimized and validated by using two electromagnetic solvers. The area occupied by this BPF is 33.6×41.24 mm2. The final circuit is a low cost BPF and can be associated with passive and active circuits due to the miniature dimensions.

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2020

The differential phase shifter is an interesting four-port passive microwave network composed of ... more The differential phase shifter is an interesting four-port passive microwave network composed of two separate lines, the main line and the reference line, and providing stable phase difference between the two output signals over the specified bandwidth of interest. The most common differential phase shifter is the coupled-line Schiffman phase shifter. In this paper, a novel 90 degrees differential microstrip phase shifter configuration employing a half wavelength transmission line loaded with three open stubs is presented, the proposed design could achieve excellent performance with low phase variation over a wide bandwidth compared to the standard Schiffman phase shifter. The simulated results accomplished with the use of CST Microwave Studio and advanced design system (ADS), were found to be in good agreement and have shown that the proposed loaded-stub phase shifter achieved less than 1.1 dB insertion loss, greater than 13 dB return loss and constant 90±5 degrees phase shift over an 89 percent bandwidth

International Journal of Electrical and Computer Engineering (IJECE), 2017

This paper presents the design of new compact antennas for ultra wide band applications. Each ant... more This paper presents the design of new compact antennas for ultra wide band applications. Each antenna consists of a rectangular patch fed by 50Ω microstrip transmission line and the ground element is a defected ground structure (DGS). The aim of this study is to improve the bandwidth of these antennas by using DGS and the modification geometry of rectangular structure, which gives new compact antennas for UWB applications. The input impedance bandwidth of the antennas with S11<-10dB is more than 10GHz, from 3GHz to more than 14 GHz. The proposed antennas are investigated and optimized by using CST microwave studio, they are validated by using another electromagnetic solver Ansoft HFSS. The measured parameters present good agreement with simulation. The final antenna structures offer excellent performances for UWB system.

International Journal of Electrical and Computer Engineering (IJECE), 2017

In this paper a design of a new antenna with modified ground plane is validated for multiband app... more In this paper a design of a new antenna with modified ground plane is validated for multiband applications. The proposed modified ground structure is incorporated with a patch antenna to boost the performance. The antenna’s entire area is 59.5x47mm2 and is printed on an FR-4 substrate and fed by a 50 Ohm microstrip line. This structure is validated in the GPS (1.56-1.58 GHz) band at 1.57 GHz, in the ISM (2.43-2.49 GHz) band at 2.45GHz and in the WiMAX (3.50-3.56 GHz) band at 3.53 GHz. These three frequency bands have good matching input impedance for, S11≤-10 dB. The antenna presents a good performance in terms of radiation pattern, and it is designed, optimized, and miniaturized by using CST-MW whose results are compared with other solvers HFSS and ADS. The results obtained by the use of the three EM solvers are in good agreement. After realization, we have tested and validated this antenna. The measurement results of the antenna present a good agreement with the numerical results.

Indonesian Journal of Electrical Engineering and Computer Science, 2019

This paper deals with the design and achievement of a novel microstrip rectifier with high conver... more This paper deals with the design and achievement of a novel microstrip rectifier with high conversion efficiency and output voltage. Firstly, we have designed a rectifier based on HSMS2820 Schottky diodes by using a series topology to convert the electromagnetic energy into DC power. Then, a stepped-impedance low pass filter was implemented to filter the unwanted harmonics generated by the non-linear Schottky diode. Both of the structures have been simulated and fabricated on an FR4 substrate with dielectric permittivity constant 4.4, thickness of 1.6 mm and loss tangent of 0.025. Good performances were confirmed throughout the measurement results and an interesting output voltage was observed.

A new design of U shaped reconfigurable antenna based on PIN diodes

2017 International Conference on Wireless Technologies, Embedded and Intelligent Systems (WITS), 2017

In this paper, we propose a novel reconfigurable patch antenna for wireless communication systems... more In this paper, we propose a novel reconfigurable patch antenna for wireless communication systems. The proposed reconfigurable antenna is based on PIN diodes associated to three U shaped resonators. The operating frequency of the proposed antenna can be tuned by changing the state of the PIN diode. In this work, we modelized the PIN diode using two different methods. This circuit is mounted on an FR-4 substrate with a thickness of 1.6mm, dielectric constant of 4.4 and tangent loss of 0.025. The simulation results are performed with CST-MW studio and verified by ADS.

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2021

This paper presents a new circular polarized micro-strip antenna with a pentagonal shape radiator... more This paper presents a new circular polarized micro-strip antenna with a pentagonal shape radiator. The proposed antenna is designed to operate in the industrial scientific medical (ISM) band at the frequency of 2.45GHz for Wireless applications. The antenna consists of a radiating pentagon patch with appropriate dimensions on the upper side of a dielectric substrate and a defective ground structure (DGS) on the other side. The pentagon patch is fed through a 50Ω microstrip line. The structure is implemented on an FR-4 substrate with a relative permittivity of 4.4, loss tangent equal to 0.025 and thickness 1.58 mm. The antenna is designed and simulated by using advanced design system (ADS) electromagnetic solver and the achieved results are validated by using another electromagnetic solver. The simulation results indicate that the designed circularly polarized (CP) pentagonal microstrip patch antenna gives good results in terms of the reflection coefficient, voltage standing wave ratio (VSWR) and, axial ratio of 1.025 at 2.45 GHz.

$Research paper thumbnail of A Circular Sierpinski fractal antenna for UWB applications$

A Circular Sierpinski fractal antenna for UWB applications

Proceedings of the 2nd International Conference on Computing and Wireless Communication Systems - ICCWCS'17, 2017

In this paper a depicted survey of a Coplanar Waveguide (CPW) printed antenna achieved by using t... more In this paper a depicted survey of a Coplanar Waveguide (CPW) printed antenna achieved by using the Sierpinski Gasket as fractal geometry in the radiator which is taken as circular shape, the iterations has been performed three times in order to improve the matching of Input Impedance at 50 Ω in the Ultra-wide band (UWB), which is the frequency range 3.1-10.4 GHz released by the Federal Communications commission (FCC). The electromagnetics solvers CST of Microwave Studio have been used to design the proposed antenna by the methods of optimization included in the software tool and to compute the coefficient of reflection and the gain radiation pattern. The FR4 has been chosen as substrate to simulate the printed antenna with an overall dimension of 34 x 43 mm2.

$Research paper thumbnail of A low cost fractal CPW fed antenna for UWB applications with a circular radiating patch$

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2020

In this study a validated antenna into simulation and through measurement has been described and ... more In this study a validated antenna into simulation and through measurement has been described and analyzed. The coplanar waveguide (CPW) technique has been chosen to feed the radiating patch while the two ground planes have been partially designed in the top side of the substrate. The fractal geometry, applied to the circular radiator, has been obtained by merging the circular and rectangular shapes. The fiberglass FR-4, with a single side of 35μm copper thickness, has been used to achieve the antenna material with a permittivity of 4.4, a thickness of 1.6 mm, a loss tangent of 0.025 and an overall dimension of 34x43 mm 2. The proposed CPW fractal antenna has been configured to operate in the frequency range 3.1-10.6 GHz published by the federal communications commission (FCC) as an ultra-wide band (UWB). To calculate the return loss, the gain, the current density and the radiation pattern of the simulated antenna, two electromagnetic solvers have been involved which are the CST microwave studio and ADS. The series of measurement have been performed by using the network analyzer and the anechoic chamber in order to confirm the computed antenna.

Handbook of Research on Advanced Trends in Microwave and Communication Engineering

This chapter presents two new microstrip multiband antennas based on fractal geometry. The purpos... more This chapter presents two new microstrip multiband antennas based on fractal geometry. The purpose is to study the behaviour of structures when applying a fractal aspect. The first antenna is designed and optimized by using Sierpinski triangle technique, it's validated in tne ISM "Industrial Scientific and Medical" band at 2.45 and 5.8 GHz bands which was designed to be suitable for wireless power transmission use, while the second proposed antenna structure is based on the hexagonal geometry, it's validated and tested for DCS (Digital Cellular System) at 1.8 GHz, for 2.45 GHz and for 5.8 GHz, as an example of application wireless mobile system is an application field.

Low cost Multi-band planar antenna for mobile phone applications

2014 International Conference on Multimedia Computing and Systems (ICMCS), 2014

In this paper a novel Multi-band planar antenna structure is presented for GSM 900, DCS 1800, 3G ... more In this paper a novel Multi-band planar antenna structure is presented for GSM 900, DCS 1800, 3G (UMTS 2000) and 4G (LTE Advanced) applications. The antenna is optimized and simulated by using CST Microwave studio, 3-dimentional full wave electromagnetic simulation software. This antenna structure has a partial ground that was optimized into simulation. After the achievement, we have tested and validated this multi-band antenna by using R&S VNA.

Heat and Mass Transfers in Honeycomb Matrix

Dans cet article,nous developpons un nouveau procede de recuperation des metaux precieux contenus... more Dans cet article,nous developpons un nouveau procede de recuperation des metaux precieux contenus dans les catalyseurs de post combustion automobile usages (CPCA) ; ce procede est base sur la vaporisation reactive sous flux de gaz oxydant chaud. Un dispositif experimental a ete concu pour effectuer cette operation. Le gaz oxydant produit par une source plasma a arc souffle, traverse le catalyseur qui est une matrice alveolaire, d'abord la matrice va se chauffer ; ce qui permettra d'arriver a une certaine temperature, ceci provoque le depart des platinoides sous forme d'oxydes gazeux. Pour optimiser les differents parametres qui regissent la vaporisation nous avons modelise les transferts de chaleur et de matiere dans la matrice alveolaire. Cette modelisation a ete faite en elaborant deux codes de calcul. Le premier concerne le transfert de chaleur et de matiere dans la veine gazeuse et a ete etablit en regime permanent, alors que le second, traitant le transfert de chale...

This paper presents analysis and design of a wideband Wilkinson power divider for wirel... more This paper presents analysis and design of a wideband Wilkinson power divider for wireless applications. The design is accomplished by transforming the lengths and impedances of the quarter wavelength sections of the conventional Wilkinson power divider into U-shaped sections. The designed power divider is simulated by using ADS Agilent technologies and CST microwave studio software. It is shown that the proposed power divider has simple topology and good performances in terms of insertion loss, port matching and isolation at all operating frequencies (1.8 GHz, 2.45 GHz and 3.55 GHz).

This paper presents a new structure of microstrip band pass filter (BPF) based on coupl... more This paper presents a new structure of microstrip band pass filter (BPF) based on coupled stepped impedance resonators. Each filter consists of two coupled stepped impedance resonators connected to microstrip feed lines. The coupled junction is utilized to connect the two BPFs to the antenna. This two band pass filters are designed and simulated to operate for the digital communication system (DCS) and Industrial Scientific and Medical (ISM) bands at 1.8 GHz and 2.45 GHz respectively. The proposed circuit presents good performances with an insertion loss lower than 2.3 dB and isolation between the two channels greater than 21 dB. The prototype of the optimized diplexer have been investigated numerically by using ADS Agilent and verified with CST microwave software.

This work presents a new planar multiband antenna based on fractal geometry. This struc... more This work presents a new planar multiband antenna based on fractal geometry. This structure is optimized and validated into simulation by using CST-MW Studio. To feed this antenna we have used a CPW line which makes it easy to be incorporated with integrated circuits. The simulation results presents a good matching input impedance and radiation pattern in the GSM band at 900 MHz and ISM band at 2.4 GHz. The final structure is a dual band fractal antenna with 70 x 70 mm² as a total area by using an FR4 substrate.

$Research paper thumbnail of Multiband fractal CPW antenna for GPS, WiMAX and IMT applications$

Multiband fractal CPW antenna for GPS, WiMAX and IMT applications

2017 International Conference on Wireless Technologies, Embedded and Intelligent Systems (WITS), 2017

This paper presents a new design of a fractal multiband antenna structure fed by coplanar wavegui... more This paper presents a new design of a fractal multiband antenna structure fed by coplanar waveguide (CPW) transmission line. The proposed antenna is optimized by using CST-MW studio. The final validated circuit is designed to operate in the Global Positioning System (GPS 1.57), Worldwide Interoperability for Microwave Access (WiMAX 2.5 – 2.69 / 3.30 – 3.80), and Advanced System of forth generation mobile communication (IMT 3.40 – 4.20 GHZ). Manifestly, it has been found that the radiation patterns of the presented antenna are still similarly to the bidirectional radiation pattern. The properties of the antennas, for instance, return losses and radiation patterns are validated into simulation by using two electromagnetic simulators HFSS and CST-MW Studio.

A novel design of a compact miniature microstrip low pass filter based on SRR

2017 International Conference on Wireless Technologies, Embedded and Intelligent Systems (WITS), 2017

In this work, a novel compact microstrip low-pass filter is designed based on square split ring r... more In this work, a novel compact microstrip low-pass filter is designed based on square split ring resonator. The SRR is used to reduce the size of the filter and to improve the good electrical performances. The dumbbell-shaped defected ground structure is introduced into the ground plane in order to achieve a desired cutoff frequency of 1.2 GHz with a ripple level less than 0.2 dB in the pass-band and an attenuation better than 20 dB in the rejected band. The proposed filter is designed on an FR-4 substrate having a thickness of 1.6mm, a dielectric constant of 4.4 and loss tangent of 0.025. The whole area of the proposed circuit is 24×26mm2. The computed results obtained by CST microwave and Ansoft HFSS are in good agreement. The size of LPF is miniaturized by 60% compared to the conventional filter.

A new design of a miniature microstrip patch antenna using Defected Ground Structure DGS

2017 International Conference on Wireless Technologies, Embedded and Intelligent Systems (WITS), 2017

The concept of Defected Ground Structures (DGS) has been developed to improve the characteristics... more The concept of Defected Ground Structures (DGS) has been developed to improve the characteristics of many microwave devices. For this purpose the DGS is also used in the microstrip antenna for some advantages such as antenna size reduction, mutual coupling reduction in antenna arrays etc… In this paper the defected ground structure (DGS) has been employed to miniaturize a microstrip patch antenna and to shift the resonance frequency from an initial value of 10 GHz to a final value at 3.5 GHz, without any change in the dimensions of the original microstrip patch antenna. This antenna is designed on a FR-4 substrate with dielectric constant 4.4 and thickness 1.6 mm and its size is 27 × 30 mm2. The antenna is designed, optimized, and miniaturized by using CST MW.