Journal of Electromagnetic Waves and Applications, 2009
ABSTRACT A rigorous full wave technique based on the transverse wave concept iterative procedure ... more ABSTRACT A rigorous full wave technique based on the transverse wave concept iterative procedure (WCIP) is used to design and model a microwave active Screen. This approach takes the advantage of the combination of the rectangular and periodic waveguide modes. We demonstrate that 18 × 18 active elements in the closed packages are sufficient to have the same amplification as in the infinite Screen configuration.
International Journal of Modelling and Simulation, 2005
AbstractAn efficient iterative method based on the concept of waves is presented to determine the... more AbstractAn efficient iterative method based on the concept of waves is presented to determine the characteristics of coplanar waveguide (CPW) and the finline step discontinuity. A two-dimensional fast Fourier transformation algorithm is introduced to simplify calculations and accelerate the convergence with reduced central processing unit time. The general formulation and implementation procedure of the method are described. The numerical results are compared with the published data obtained by other methods. This comparison shows a good agreement.
Objectives: In this paper we make a comparative study between two adapted methods for the estimat... more Objectives: In this paper we make a comparative study between two adapted methods for the estimation of the angle of departure and the angle of arrival in a Bistatic multiple input multiple output radar system. Methods: We have adapted the high resolution methods known in the literature to the estimation of the parameters of the sources with a Bistatic radar equipped with an antennas array on the transmit station and on that of the receive one. The two methods are a Derived Multiple Signal Classification method (D-MUSIC) and the Derived Propagator method (D-Propagator). Findings: Through simulation results we have conducted a comparative study between the different adapted methods. We take advantage of each one for different pçolpscenarios in terms of accuracy and resolution.The two proposed methods showed good performances even for low signal-to-noise ratio. In addition, the parameters of the radar systems have a great influence on the performance of the estimators. For this reason, a thorough study on the precision of the high resolution methods according to these parameters was made. Application: By varying the Radar Cross Section we noticed the superiority of D-MUSIC method compared to D-Propagator method for a limited reflection surface what was not the case in the other scenarios where the propagator showed remarkable superiority.
American Journal of Engineering and Applied Sciences, 2015
The purpose of this study is the study and modeling of phenomenon 'interaction between the antenn... more The purpose of this study is the study and modeling of phenomenon 'interaction between the antenna and the human body' by the Artificial Neural Network (ANN). This technique is based on mathematical formulations and a base of learning who took simulations by noted trade CST MS. An example of the interaction between a body, which the dielectric properties are given and a dipole antenna, has been studied. The results validate the new approach. The good agreement between the results of the given simulation published justifies the modeling process and validates the current approach of the analysis.
2015 Radio and Antenna Days of the Indian Ocean (RADIO), 2015
A high gain resonant cavity antenna using a new Frequency Selective Surface (FSS) superstrate is ... more A high gain resonant cavity antenna using a new Frequency Selective Surface (FSS) superstrate is presented. In the proposed design, the simple superstrate is composed of two different dielectric slabs with different material proprieties and thicknesses, both are arranged to be highly reflective to achieve gain and directivity enhancement. Furthermore, the Software CST Microwave Studio is used to extract the directivity and the radiation pattern of the FSS resonator design. The proposed antenna using a single probe feeds is designed to operate at 5.8-6.2 GHz region. The measurement results are included for supporting the modelings and simulations.
2014 World Symposium on Computer Applications & Research (WSCAR), 2014
ABSTRACT A 4 bits digital phase shifter is designed and simulated. It is based on 3-db hybrid cou... more ABSTRACT A 4 bits digital phase shifter is designed and simulated. It is based on 3-db hybrid coupler and totally twelve switches are used. The simulation results indicate an insertion loss better than -4db, a return loss less than -20 db and an error phase varied between 0.01° and 0.6° at 2.45 GHz. to achieve a 6 bits phase shifter, we increased the number of stages. This phase shifter present an insertion loss better than -5db, a return loss less than -20db and an error phase varied between 0.1° and 1.7°. But, the circuit presents a large size. The Ga As FET switch used for switching is characterized by a very low DC power consumption, a fast switching speed and a low cost. Also, an array antenna of 8 patch elements connected to a 4 bits phase sifter is designed. The simulated results of the array indicate a return loss better than -10db over 2.4-2.5 GHz and a gain equal 14 db. Index Terms— Reflection type phase shifter, Ga As FET switch, Digital phase shifter, directive coupler, phased array antenna. I-INTRODUCTION In many fields of electronics, it is often necessary to change the phase of signal. A microwave phase shifter is a circuit which shifts the phase of an input microwave signal on the basis of the phase shift characteristics of the circuit and output the resultant signal phase. This device will shift a signal to a desired phase location via a digital or analog command and can be accomplished in a passive device. Phase shifters have a wide area of application, such as in radar, satellite communication systems, measurement setup and in phased array antenna [6]. In general, they represent a great part of the production cost of a phased array antenna. Generally, there are three technologies of manufacture of a digital phase shifter: The MEMS (Micro Electro Mechanical System) phase shifter, the FET phase shifter, and the PIN diode phase shifter [1]. Phase shifter MEMS have many advantages such as small size, wide frequency band, low insertion loss, good insulation, low fuel consumption and linearity. But these switches can only support powers of few Watts, a limited output and a switching speed slower than the FET. In [9], [10] a microelectromechanical switch is used to realize a 2 and 3 bit phase shifter, these phase shifter are beneficial by a low power consumption, size, weight and cost . The PIN phase shifter can control a large power; can function at higher frequencies reaching to 20 GHZ. It is also available in the market and is easy to manufacture [7]. A many PIN diode phases shifters are designed and fabricated [11], [12]. For example, in [13] a 4 bits phase shifter based on PIN diode shows a low insertion loss and a fast switching times. The FET switch has the advantage of a fixed and fast switching speed, very low dc power consumption and compatibility for monolithic integration. The FET phase shifter has a small size and a low cost [1]. In [2] a FET switch is designed and used to realize a 6 bit phase shifter operates in c band. The switch is consists of a seven element RLC network. The FET is characterised by a small size and a very fast switching times. The phase shifter has demonstrated excellent phase accuracy and a good phase tracking. Also, this phase shifter has shown a small size and negligible dc power dissipation and a nanosecond switching times. Another type of Ga As FET phase shifter is described in [3], The circuit is based on a SPDT dual-gate FET switchable amplifier design. The structure realised by cascading four monolithic active 90° phase shifter the measurement shows a phase error less than 5°. Invention of integrated circuit (IC) technology brought many advantages to the phase shifter. For example, in [4] a 5 bit MMIC phase shifter is presented, this circuit characterised by a small size with a 1.693mm×0.75mm. measurement performance demonstrated 5db insertion loss and 3° phase error. In this paper a 4bit digital phase shifter using on Ga As FET switches is presented. This phase shifter is concept on the reflection topology using a 3-db hybrid coupler. The reflection topology has the advantage of requiring only half length of line that is required for the switched line phase shifter to achieve the same phase shift. This feature is extremely important when the operational frequency is relatively low (the wavelength is relatively large) such as in the S-band, and the cost savings by using this approach could be significant due to the decreased area of the circuitry.
2010 Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF), 2010
ABSTRACT Substrate crosstalk and RF losses in HR-SOI, and the introduction of a stabilized polysi... more ABSTRACT Substrate crosstalk and RF losses in HR-SOI, and the introduction of a stabilized polysilicon layer are deeply investigated. A new equivalent lumped circuit to model different substrate types and resistivities, and SiO2-Si interface qualities is proposed and validated by simulation and experimental data. It is also valid to model the introduction of high-trap density at the interface, and it successfully explains the higher measured values of substrate crosstalk at low frequencies for HR-Si substrates.
International Journal on Communications Antenna and Propagation (IRECAP), 2014
An efficient iterative technique based on the concept of wave WCIP and a Fast Mode Transformation... more An efficient iterative technique based on the concept of wave WCIP and a Fast Mode Transformation FMT is used to analysis an almost periodic circuits. These structures are used as the resonator circuits for modelling applications metamaterials. We synthesize almost periodic circuits with unit cells of series capacitor or inductor in orthogonal directions.
IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313)
ABSTRACT The radiation fields of a conducting obstacle coated by a thin dielectric layer are anal... more ABSTRACT The radiation fields of a conducting obstacle coated by a thin dielectric layer are analysed using a wave iterative concept process. Applying this method to a circular cylinder the radar cross section is then extracted and compared successfully to existing results.
2009 16th IEEE International Conference on Electronics, Circuits and Systems - (ICECS 2009), 2009
ABSTRACT An adaptive antenna system consists of a combination of multiple antenna elements with a... more ABSTRACT An adaptive antenna system consists of a combination of multiple antenna elements with a signal-processing capability to optimize its radiation and/or reception pattern automatically in response to the signal environment. In a telecommunication system, adaptive antenna system is the port through which radio frequency (RF) energy is coupled from the transmitter to the environment and, in reverse, to the receiver from the environment. In this paper, an efficient method for the pattern synthesis of the linear antenna arrays with the prescribed nulling and steering lobe is presented. The proposed method is based on LMS algorithm. This paper proposes the novel architecture for implementing a least mean square (LMS) algorithm, using an 8 quasi-Yagi array with its feeding system.
The main motivation for this work is how to handle the circumvent problem encountered in decorrel... more The main motivation for this work is how to handle the circumvent problem encountered in decorrelating perfect coherent multipath signals over MIMO-CDMA channel with small number of sensors and few data snapshots. The authors propose a new iterative space-time lifting preprocessing (ISTLP) decorrelating scheme that guarantees a perfect decorrelating of a great number of impinging signals even when they are fully correlated and overlaying in space and time domains. It is based on exploiting iteratively the spatial and temporal redundancies arising from multiple antennas and multiple slots. The temporal lifting scheme is introduced first, for efficient tracking and cancelling of ISI, MAI and noise effects within the bank of the N-tapped-delay-lines associated with the user of interest. Secondly, this iterative multi-resolution approach will be coupled to a preprocessing scheme to allow easy transformation of resulting temporal-lifted covariance matrix from time domain to an equivalent Vandermonde structure in frequency domain to be exploited in spatial lifting step. Two detection criteria are therefore established to attempt the convergence state in ISTLP algorithm. Finally, a JADE-Capon method based on ST-MVDR beamformer is applied to the spatial-temporal-lifted preprocessed covariance matrix to compute the joint azimuth-direction-of-arrival and delay of desired K i multipath signals. The efficacy and high resolution capability of the proposed estimation approach is supported by numerical simulation results.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
A simple and efficient configuration of Switched Beam Antenna arrays based on 1D Fabry-Pérot Lea... more A simple and efficient configuration of Switched Beam Antenna arrays based on 1D Fabry-Pérot Leaky Wave Antenna (FPLWA) is presented working at 5.8 GHz. The single 1D FPLWA is formed by a simple low gain patch antenna covered by a PRS screen formed by a Metal Strip Grating (MSG). Simulated results including return loss and switched beams are presented. multiple orthogonal beams (six beams) of 10dBi of gain with low Side Lobes Level (SLL) (of about -15 dB) and 360° of coverage are produced. This SBA structure is suitable for WLAN communication systems.
2010 IEEE Antennas and Propagation Society International Symposium, 2010
A 4x4 wideband multilayer Butler matrix has been designed using a bi-layer structure. In the prop... more A 4x4 wideband multilayer Butler matrix has been designed using a bi-layer structure. In the proposed design, a combination of single and multilayer elliptic directional couplers is employed to widen the bandwidth and to avoid using any crossovers as conventional matrices. Simulated results show a good agreement and a bandwidth of about 2 GHz was achieved. Furthermore, the proposed matrix
2011 International Conference on Communications, Computing and Control Applications (CCCA), 2011
... Where /θ(ϕ) = ∣ n=N ∑ n=1 anej(kxnsinθ+ϕn)∣2 (3) ... 3) Phase of change: this third operator ... more ... Where /θ(ϕ) = ∣ n=N ∑ n=1 anej(kxnsinθ+ϕn)∣2 (3) ... 3) Phase of change: this third operator is introduced to mitigate the disappearance of information (bits) of the popu-lation. Its role consists in modifying by chance, with a certain probability, the value of a bit [3]. IV. ...
Patch antennas plane networks have been used largely in communication systems. Their capability t... more Patch antennas plane networks have been used largely in communication systems. Their capability to change radiation pattern electronically, multi-beam capacity and high spatial resolution has made them attractive for mobile communication applications. The work presented in this paper refers to the synthesis of periodic patch antennas plane networks supplied with coaxial lines. The method of synthesis used for this type of networks let's possible an optimal approach for the desired radiation pattern specified by a gauge sensible for source excitation and space distribution of the radiant sources. The development of the synthesis is based on the neural networks technique.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowsk... more This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowski fractal geometries. Two electro-textile materials namely Flectron and Zelt are considered for the design of flexible microstrip antennas. In both cases, polyester fabric material has been employed as dielectric medium. In the basic design both the antennas are designed for WLAN applications. The Flectron antenna provides a gain of 6.54 dB with an impedance bandwidth of 132 MHz whereas, the Zelt antenna offers a gain of 7.4 dB and an impedance bandwidth of 104 MHz. By applying Minkowski fractal geometry to the antennas, miniaturization is achieved. In its first iteration, antenna designs are optimized and tuned to WiBro band and in the second iteration, antennas are further miniaturized in order to make them suitable for GSM 1900 applications. In these two bands, the gain and efficiency of both Flectron and Zelt antennas conform to their respective wireless standards. The simulation studies reveal that Zelt antenna yields better results compared to Flectron antenna.
Journal of Electromagnetic Waves and Applications, 2009
ABSTRACT A rigorous full wave technique based on the transverse wave concept iterative procedure ... more ABSTRACT A rigorous full wave technique based on the transverse wave concept iterative procedure (WCIP) is used to design and model a microwave active Screen. This approach takes the advantage of the combination of the rectangular and periodic waveguide modes. We demonstrate that 18 × 18 active elements in the closed packages are sufficient to have the same amplification as in the infinite Screen configuration.
International Journal of Modelling and Simulation, 2005
AbstractAn efficient iterative method based on the concept of waves is presented to determine the... more AbstractAn efficient iterative method based on the concept of waves is presented to determine the characteristics of coplanar waveguide (CPW) and the finline step discontinuity. A two-dimensional fast Fourier transformation algorithm is introduced to simplify calculations and accelerate the convergence with reduced central processing unit time. The general formulation and implementation procedure of the method are described. The numerical results are compared with the published data obtained by other methods. This comparison shows a good agreement.
Objectives: In this paper we make a comparative study between two adapted methods for the estimat... more Objectives: In this paper we make a comparative study between two adapted methods for the estimation of the angle of departure and the angle of arrival in a Bistatic multiple input multiple output radar system. Methods: We have adapted the high resolution methods known in the literature to the estimation of the parameters of the sources with a Bistatic radar equipped with an antennas array on the transmit station and on that of the receive one. The two methods are a Derived Multiple Signal Classification method (D-MUSIC) and the Derived Propagator method (D-Propagator). Findings: Through simulation results we have conducted a comparative study between the different adapted methods. We take advantage of each one for different pçolpscenarios in terms of accuracy and resolution.The two proposed methods showed good performances even for low signal-to-noise ratio. In addition, the parameters of the radar systems have a great influence on the performance of the estimators. For this reason, a thorough study on the precision of the high resolution methods according to these parameters was made. Application: By varying the Radar Cross Section we noticed the superiority of D-MUSIC method compared to D-Propagator method for a limited reflection surface what was not the case in the other scenarios where the propagator showed remarkable superiority.
American Journal of Engineering and Applied Sciences, 2015
The purpose of this study is the study and modeling of phenomenon 'interaction between the antenn... more The purpose of this study is the study and modeling of phenomenon 'interaction between the antenna and the human body' by the Artificial Neural Network (ANN). This technique is based on mathematical formulations and a base of learning who took simulations by noted trade CST MS. An example of the interaction between a body, which the dielectric properties are given and a dipole antenna, has been studied. The results validate the new approach. The good agreement between the results of the given simulation published justifies the modeling process and validates the current approach of the analysis.
2015 Radio and Antenna Days of the Indian Ocean (RADIO), 2015
A high gain resonant cavity antenna using a new Frequency Selective Surface (FSS) superstrate is ... more A high gain resonant cavity antenna using a new Frequency Selective Surface (FSS) superstrate is presented. In the proposed design, the simple superstrate is composed of two different dielectric slabs with different material proprieties and thicknesses, both are arranged to be highly reflective to achieve gain and directivity enhancement. Furthermore, the Software CST Microwave Studio is used to extract the directivity and the radiation pattern of the FSS resonator design. The proposed antenna using a single probe feeds is designed to operate at 5.8-6.2 GHz region. The measurement results are included for supporting the modelings and simulations.
2014 World Symposium on Computer Applications & Research (WSCAR), 2014
ABSTRACT A 4 bits digital phase shifter is designed and simulated. It is based on 3-db hybrid cou... more ABSTRACT A 4 bits digital phase shifter is designed and simulated. It is based on 3-db hybrid coupler and totally twelve switches are used. The simulation results indicate an insertion loss better than -4db, a return loss less than -20 db and an error phase varied between 0.01° and 0.6° at 2.45 GHz. to achieve a 6 bits phase shifter, we increased the number of stages. This phase shifter present an insertion loss better than -5db, a return loss less than -20db and an error phase varied between 0.1° and 1.7°. But, the circuit presents a large size. The Ga As FET switch used for switching is characterized by a very low DC power consumption, a fast switching speed and a low cost. Also, an array antenna of 8 patch elements connected to a 4 bits phase sifter is designed. The simulated results of the array indicate a return loss better than -10db over 2.4-2.5 GHz and a gain equal 14 db. Index Terms— Reflection type phase shifter, Ga As FET switch, Digital phase shifter, directive coupler, phased array antenna. I-INTRODUCTION In many fields of electronics, it is often necessary to change the phase of signal. A microwave phase shifter is a circuit which shifts the phase of an input microwave signal on the basis of the phase shift characteristics of the circuit and output the resultant signal phase. This device will shift a signal to a desired phase location via a digital or analog command and can be accomplished in a passive device. Phase shifters have a wide area of application, such as in radar, satellite communication systems, measurement setup and in phased array antenna [6]. In general, they represent a great part of the production cost of a phased array antenna. Generally, there are three technologies of manufacture of a digital phase shifter: The MEMS (Micro Electro Mechanical System) phase shifter, the FET phase shifter, and the PIN diode phase shifter [1]. Phase shifter MEMS have many advantages such as small size, wide frequency band, low insertion loss, good insulation, low fuel consumption and linearity. But these switches can only support powers of few Watts, a limited output and a switching speed slower than the FET. In [9], [10] a microelectromechanical switch is used to realize a 2 and 3 bit phase shifter, these phase shifter are beneficial by a low power consumption, size, weight and cost . The PIN phase shifter can control a large power; can function at higher frequencies reaching to 20 GHZ. It is also available in the market and is easy to manufacture [7]. A many PIN diode phases shifters are designed and fabricated [11], [12]. For example, in [13] a 4 bits phase shifter based on PIN diode shows a low insertion loss and a fast switching times. The FET switch has the advantage of a fixed and fast switching speed, very low dc power consumption and compatibility for monolithic integration. The FET phase shifter has a small size and a low cost [1]. In [2] a FET switch is designed and used to realize a 6 bit phase shifter operates in c band. The switch is consists of a seven element RLC network. The FET is characterised by a small size and a very fast switching times. The phase shifter has demonstrated excellent phase accuracy and a good phase tracking. Also, this phase shifter has shown a small size and negligible dc power dissipation and a nanosecond switching times. Another type of Ga As FET phase shifter is described in [3], The circuit is based on a SPDT dual-gate FET switchable amplifier design. The structure realised by cascading four monolithic active 90° phase shifter the measurement shows a phase error less than 5°. Invention of integrated circuit (IC) technology brought many advantages to the phase shifter. For example, in [4] a 5 bit MMIC phase shifter is presented, this circuit characterised by a small size with a 1.693mm×0.75mm. measurement performance demonstrated 5db insertion loss and 3° phase error. In this paper a 4bit digital phase shifter using on Ga As FET switches is presented. This phase shifter is concept on the reflection topology using a 3-db hybrid coupler. The reflection topology has the advantage of requiring only half length of line that is required for the switched line phase shifter to achieve the same phase shift. This feature is extremely important when the operational frequency is relatively low (the wavelength is relatively large) such as in the S-band, and the cost savings by using this approach could be significant due to the decreased area of the circuitry.
2010 Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF), 2010
ABSTRACT Substrate crosstalk and RF losses in HR-SOI, and the introduction of a stabilized polysi... more ABSTRACT Substrate crosstalk and RF losses in HR-SOI, and the introduction of a stabilized polysilicon layer are deeply investigated. A new equivalent lumped circuit to model different substrate types and resistivities, and SiO2-Si interface qualities is proposed and validated by simulation and experimental data. It is also valid to model the introduction of high-trap density at the interface, and it successfully explains the higher measured values of substrate crosstalk at low frequencies for HR-Si substrates.
International Journal on Communications Antenna and Propagation (IRECAP), 2014
An efficient iterative technique based on the concept of wave WCIP and a Fast Mode Transformation... more An efficient iterative technique based on the concept of wave WCIP and a Fast Mode Transformation FMT is used to analysis an almost periodic circuits. These structures are used as the resonator circuits for modelling applications metamaterials. We synthesize almost periodic circuits with unit cells of series capacitor or inductor in orthogonal directions.
IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313)
ABSTRACT The radiation fields of a conducting obstacle coated by a thin dielectric layer are anal... more ABSTRACT The radiation fields of a conducting obstacle coated by a thin dielectric layer are analysed using a wave iterative concept process. Applying this method to a circular cylinder the radar cross section is then extracted and compared successfully to existing results.
2009 16th IEEE International Conference on Electronics, Circuits and Systems - (ICECS 2009), 2009
ABSTRACT An adaptive antenna system consists of a combination of multiple antenna elements with a... more ABSTRACT An adaptive antenna system consists of a combination of multiple antenna elements with a signal-processing capability to optimize its radiation and/or reception pattern automatically in response to the signal environment. In a telecommunication system, adaptive antenna system is the port through which radio frequency (RF) energy is coupled from the transmitter to the environment and, in reverse, to the receiver from the environment. In this paper, an efficient method for the pattern synthesis of the linear antenna arrays with the prescribed nulling and steering lobe is presented. The proposed method is based on LMS algorithm. This paper proposes the novel architecture for implementing a least mean square (LMS) algorithm, using an 8 quasi-Yagi array with its feeding system.
The main motivation for this work is how to handle the circumvent problem encountered in decorrel... more The main motivation for this work is how to handle the circumvent problem encountered in decorrelating perfect coherent multipath signals over MIMO-CDMA channel with small number of sensors and few data snapshots. The authors propose a new iterative space-time lifting preprocessing (ISTLP) decorrelating scheme that guarantees a perfect decorrelating of a great number of impinging signals even when they are fully correlated and overlaying in space and time domains. It is based on exploiting iteratively the spatial and temporal redundancies arising from multiple antennas and multiple slots. The temporal lifting scheme is introduced first, for efficient tracking and cancelling of ISI, MAI and noise effects within the bank of the N-tapped-delay-lines associated with the user of interest. Secondly, this iterative multi-resolution approach will be coupled to a preprocessing scheme to allow easy transformation of resulting temporal-lifted covariance matrix from time domain to an equivalent Vandermonde structure in frequency domain to be exploited in spatial lifting step. Two detection criteria are therefore established to attempt the convergence state in ISTLP algorithm. Finally, a JADE-Capon method based on ST-MVDR beamformer is applied to the spatial-temporal-lifted preprocessed covariance matrix to compute the joint azimuth-direction-of-arrival and delay of desired K i multipath signals. The efficacy and high resolution capability of the proposed estimation approach is supported by numerical simulation results.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
A simple and efficient configuration of Switched Beam Antenna arrays based on 1D Fabry-Pérot Lea... more A simple and efficient configuration of Switched Beam Antenna arrays based on 1D Fabry-Pérot Leaky Wave Antenna (FPLWA) is presented working at 5.8 GHz. The single 1D FPLWA is formed by a simple low gain patch antenna covered by a PRS screen formed by a Metal Strip Grating (MSG). Simulated results including return loss and switched beams are presented. multiple orthogonal beams (six beams) of 10dBi of gain with low Side Lobes Level (SLL) (of about -15 dB) and 360° of coverage are produced. This SBA structure is suitable for WLAN communication systems.
2010 IEEE Antennas and Propagation Society International Symposium, 2010
A 4x4 wideband multilayer Butler matrix has been designed using a bi-layer structure. In the prop... more A 4x4 wideband multilayer Butler matrix has been designed using a bi-layer structure. In the proposed design, a combination of single and multilayer elliptic directional couplers is employed to widen the bandwidth and to avoid using any crossovers as conventional matrices. Simulated results show a good agreement and a bandwidth of about 2 GHz was achieved. Furthermore, the proposed matrix
2011 International Conference on Communications, Computing and Control Applications (CCCA), 2011
... Where /θ(ϕ) = ∣ n=N ∑ n=1 anej(kxnsinθ+ϕn)∣2 (3) ... 3) Phase of change: this third operator ... more ... Where /θ(ϕ) = ∣ n=N ∑ n=1 anej(kxnsinθ+ϕn)∣2 (3) ... 3) Phase of change: this third operator is introduced to mitigate the disappearance of information (bits) of the popu-lation. Its role consists in modifying by chance, with a certain probability, the value of a bit [3]. IV. ...
Patch antennas plane networks have been used largely in communication systems. Their capability t... more Patch antennas plane networks have been used largely in communication systems. Their capability to change radiation pattern electronically, multi-beam capacity and high spatial resolution has made them attractive for mobile communication applications. The work presented in this paper refers to the synthesis of periodic patch antennas plane networks supplied with coaxial lines. The method of synthesis used for this type of networks let's possible an optimal approach for the desired radiation pattern specified by a gauge sensible for source excitation and space distribution of the radiant sources. The development of the synthesis is based on the neural networks technique.
2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014
This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowsk... more This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowski fractal geometries. Two electro-textile materials namely Flectron and Zelt are considered for the design of flexible microstrip antennas. In both cases, polyester fabric material has been employed as dielectric medium. In the basic design both the antennas are designed for WLAN applications. The Flectron antenna provides a gain of 6.54 dB with an impedance bandwidth of 132 MHz whereas, the Zelt antenna offers a gain of 7.4 dB and an impedance bandwidth of 104 MHz. By applying Minkowski fractal geometry to the antennas, miniaturization is achieved. In its first iteration, antenna designs are optimized and tuned to WiBro band and in the second iteration, antennas are further miniaturized in order to make them suitable for GSM 1900 applications. In these two bands, the gain and efficiency of both Flectron and Zelt antennas conform to their respective wireless standards. The simulation studies reveal that Zelt antenna yields better results compared to Flectron antenna.
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Papers by A. Gharsallah