Ahmed Attiya - Academia.edu (original) (raw)

Papers by Ahmed Attiya

2013 30th National Radio Science Conference (NRSC), 2013

Analysis and design of a coaxial leaky wave antenna with partially reflecting outer surface are p... more Analysis and design of a coaxial leaky wave antenna with partially reflecting outer surface are presented. The leaky wave properties are controlled by adjusting the surface impedance of the outer surface, the filling dielectric constant and the dimensions of the inner and outer radii. The required surface impedance of the outer surface is implemented by using periodic slits in a perfect conducting outer cylinder. Simple analytical form is used to obtain the dimensions of theses periodic slits. An example for designing a coaxial leaky wave antenna is discussed in detail and is also verified and tuned up by using full wave numerical simulation.

In this paper, a model is presented to simulate wave propagation in indoor corridors with partial... more In this paper, a model is presented to simulate wave propagation in indoor corridors with partially reflecting walls. The model is based on combination of modal analysis, dyadic Green's function, mode matching method and generalized scattering matrix. A new approach to simulate the effect of partial reflectivity of the walls of the waveguide model is proposed. This approach is based on approximating the fields inside the space of the actual waveguide section by equivalent waveguide sections of larger dimensions with PEC (Perfect Electric Conductor) walls. A simple scenario is considered in order to check the accuracy of this model. This scenario is verified by comparing experimental and numerical simulation results. The obtained results show that the proposed model is suitable for predicting accurate electric field strength due to an electromagnetic source in an indoor environment with partially reflecting boundaries.

Progress in Electromagnetics Research B, 2012

The problem of direction-of-arrival (DOA) estimation by using spectral search for a non-uniform p... more The problem of direction-of-arrival (DOA) estimation by using spectral search for a non-uniform planar array is addressed. New search methods for DOA estimation based on piecewise interpolation are proposed. The relationships between these methods and Fourier-Domain (FD) root-MUSIC are discussed. The proposed methods are based on dividing the multiple signal classification (MUSIC) null-spectrum function into a number of equal subintervals. These subintervals are interpolated by using low-degree polynomials. Piecewise interpolation methods based on elementary functions are used to reduce the required computations of MUSIC null-spectrum function. This property reduces the computational complexity compared with line-search methods for DOA estimation. The Cramér Rao Lower Bound (CRB) is used as a benchmark to check the accuracy and validity of the proposed methods.

Research Square (Research Square), Jan 23, 2023

A deep-learning-based model to automate the design of dual-band coupled-line trans-directional (C... more A deep-learning-based model to automate the design of dual-band coupled-line trans-directional (CL-TRD) coupler can greatly improve upon the current techniques that rely on complicated analysis. In this paper, we propose a convolutional neural network (CNN), which is a type of deep learning, which can rapidly output the parameters of dual-band directional couplers corresponding to theoretical (ideal) speci cations of the electrical parameters through an inverse model. The neural network training data is generated by the use of electromagnetic simulation tool HFSS by varying the geometrical design parameters of the coupler. In order to validate the robustness of the CNN inverse model, it is applied on a 3-dB dual-band CL-TRD coupler operating at 1.2/4 GHz, and compared with a shallow neural network namely, radial basis function neural network (RBFNN). The coupler parameters designed by both neural networks are veri ed by HFSS. The results reveal that the CNN simulated S-parameters and output ports phase difference are in good agreements with the ideal ones compared to those of RBFNN with more accuracy and speed. The designed coupler is fabricated and measured for veri cation.

Applied Computational Electromagnetics Society Journal, Dec 29, 2022

Tuning a microwave filter is a challenging problem due to its complexity. Extracting coupling mat... more Tuning a microwave filter is a challenging problem due to its complexity. Extracting coupling matrix from given S-parameters is essential for ?lter tuning and design. In this paper, a deep-learning-based neural network namely, a convolutional neural network (CNN) is proposed to extract coupling matrix from Sparameters of microwave filters. The training of the proposed CNN is based on a circuit model. In order to exhibit the robustness of the new technique, it is applied on 5-and 8-pole filters and compared with a shallow neural network namely, radial basis function neural network (RBFNN). The results reveal that the CNN can extract the coupling matrix of target S-parameters with high accuracy and speed.

In this paper, a model is presented to simulate wave propagation in indoor corridors and tunnels ... more In this paper, a model is presented to simulate wave propagation in indoor corridors and tunnels with imperfectly conducting walls. The model is based on the waveguiding effect of corridors and tunnels. This approach is based on assuming that the boundaries of the waveguide section are constant impedance surface as the surface impedance of the wall is almost independent of the angle of the wave incidence onto the wall. An analytical approach for the calculation of the signal correlation between the transmitters and receivers elements in tunnels and indoor corridors is proposed. A new approach for determining the best locations of the indoor access points is introduced based on minimum correlation between sources with minimum cross talk. A scenario is considered in order to check the accuracy of this model. This scenario is verified by comparing experimental and numerical simulation results. Good agreement is achieved.

ABSTRACT This paper presents the design of different types of chip-size antennas, which are suita... more ABSTRACT This paper presents the design of different types of chip-size antennas, which are suitable for wireless sensors such as a single frequency linear polarized antenna, a dual frequency antenna with linear polarization, and a single frequency circularly polarized antenna. The proposed antennas are used for short-range wireless microsystem applications and operate in 2.45 GHz and 5-6 GHz ISM bands. The fabrication and measurement of the single frequency linear polarized antenna are introduced.

Despite the advantages and importance of conventional linear regulators, low efficiency of about ... more Despite the advantages and importance of conventional linear regulators, low efficiency of about 40% is one of the main corresponding drawbacks. Supercapacitor assisted low dropout regulator (SCALDO), a linear DC to DC technique that can be used to duplicate efficiency. Therefore, supercapacitor is playing a crucial role to maximize the efficiency as a result of nearly lossless voltage dropper element, which minimize the losses in the pass element and power semiconductors. This work represents the mathematical principles of SCALDO and a simple implementation with simple and costly effective electronic components contrary to the traditional techniques. The proposed low dropout regulator is used to convert 12V to 5V. The linear regulator based on high efficiency SCALDO technique makes it appropriate for solar cell power systems applications.

Progress in Electromagnetics Research C, 2021

This paper presents a MIMO antenna system composed of eight wideband horizontal dualloop antenna ... more This paper presents a MIMO antenna system composed of eight wideband horizontal dualloop antenna elements. Each dual-loop antenna is printed on both sides of a smart phone board. The unit element antenna is designed to operate in the frequency range from 3.2 GHz to 5 GHz. The performance of the MIMO system is then analyzed. The performance of the obtained MIMO system in the frequency range from 3.2 GHz to 4.8 GHzis characterized by input reflection coefficient which is less than −6 dB for all antenna elements, and the isolation between the elements is larger than 15 dB. The total efficiency is greater than 55% over the entire band (3.2-4.8 GHz). Parameters of the multichannel antennas including envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CLL) are analyzed to evaluate the performance of the MIMO system. The effect of the human hand and head on the performance of this MIMO antenna is also investigated. In addition, the effect of the radiated fields on the human body is also studied. The Specific Absorption Rate (SAR) value is found to be less than 0.8 W/kg. The MIMO system antenna is fabricated and measured. Good agreements are obtained between the simulated and measured parameters. The proposed MIMO system is applicable to the 5G N48, N77, and N78 bands.

International Journal of Electrical and Computer Engineering, Apr 1, 2022

IEEE Access, 2022

This paper presents a wideband eight-port multiple-input-multiple-output (MIMO) circularly polari... more This paper presents a wideband eight-port multiple-input-multiple-output (MIMO) circularly polarized antenna system for mm-wave applications. The proposed antenna element is an L-shape microstrip line with a series fishtail stubs on one side. The spacing between these stubs is adjusted to be a guided wavelength at the center frequency. These fishtail stubs are used to cancel the anti-phase magnetic currents to enhance the radiated fields from the microstrip line. A 90 • phase difference between the fields of the two arms of the L-shape is obtained by shifting the feeding point from the center of the corner by one eighth guided wavelength. This 90 • phase difference introduces the required circular polarization. The proposed antenna covers the frequency range from 27.5 up to 31 GHz, which is suitable for mm-wave N261 5G-band which cover the range from 27.5 to 28.35 GHz. These antenna elements are arranged on the four corners of a rectangular substrate to configure the proposed MIMO antenna system. Different parameters of this MIMO antenna are investigated by using numerical simulation and verified by experimental results.

International Journal of Rf and Microwave Computer-aided Engineering, Jun 7, 2020

In this article the analysis and design of a dual circularly polarized 4 × 4 antenna array operat... more In this article the analysis and design of a dual circularly polarized 4 × 4 antenna array operating in Ku band are discussed with emphasis on its sequential feeding network. The proposed antenna element is composed of stacked circular patches fed by a branch line coupler to introduce dual circular polarization. These antenna elements are arranged into 2 × 2 sequential fed antenna arrays with two separate sequential feeding networks for LH and RH circular polarizations. These 2 × 2 sequential fed antenna arrays are arranged to compose the proposed 4 × 4 antenna array. The proposed feeding network is implements on a single layer. Due to the coupling between the lines of the complete feeding network, matching and axial ratio of the complete antenna are degraded. Matching stubs at appropriate points on the complete feeding network are used to adjust the total performance of the designed 4 × 4 antenna array. Simulation results by using both HFSS and CST are presented for comparison. In addition, experimental verifications are presented.

Progress in Electromagnetics Research C, 2023

In this paper, a new artificial magnetic conductor (AMC) structure is proposed to enhance the per... more In this paper, a new artificial magnetic conductor (AMC) structure is proposed to enhance the performance of an ultra-wideband (UWB) antenna for wireless communication networks. A fractal configuration is used to introduce the UWB performance of the proposed antenna. The antenna is composed of a modified rectangular patch antenna with a tapered section fed by a coplanar waveguide (CPW) with a total size of 24 × 20 × 1.5 mm 3. The antenna is backed by an AMC. The proposed AMC unit consists of a square patch surrounded by four slotted square rings. This unit cell exhibits an in-phase reflection from 6.3 GHz to 10 GHz. The obtained bandwidth of the antenna with AMC is 110% from 3.2 GHz to 11 GHz which covers the entire UWB range. The peak gain of 7.2 dB is accomplished with a compact size of 40 × 40 × 6.5 mm 3 , 0.95 × 0.95 × 0.15λ o at 7.1 GHz. The proposed UWB antenna-AMC is fabricated and measured for verification.

International Journal of Microwave and Wireless Technologies, Jul 5, 2021

Achieving robust and fast two-dimensional adaptive beamforming of phased array antennas is a chal... more Achieving robust and fast two-dimensional adaptive beamforming of phased array antennas is a challenging problem due to its high-computational complexity. To address this problem, a deep-learning-based beamforming method is presented in this paper. In particular, the optimum weight vector is computed by modeling the problem as a convolutional neural network (CNN), which is trained with I/O pairs obtained from the optimum Wiener solution. In order to exhibit the robustness of the new technique, it is applied on an 8 × 8 phased array antenna and compared with a shallow (non-deep) neural network namely, radial basis function neural network. The results reveal that the CNN leads to nearly optimal Wiener weights even in the presence of array imperfections.

This paper presents a new textile antenna for L1 GPS application. The textile antenna is based on... more This paper presents a new textile antenna for L1 GPS application. The textile antenna is based on a grounded flannel substrate (100% cotton). The designed textile fractal antenna is integrated with caps of different materials. The effect of the cap on the performance of the designed antenna is investigated. The textile antenna integrated with a cap is studied also in the presence of a human head to obtain the effect of the human head on the performance of the designed antenna. In addition the specific absorption rate (SAR) inside the human head due to the antenna is also studied.

Journal of Electromagnetic Waves and Applications, Jun 28, 2016

Abstract This paper introduces an analytical solution for a dielectric rod leaky wave antenna loa... more Abstract This paper introduces an analytical solution for a dielectric rod leaky wave antenna loaded by a metasurface. The advantage of adding metasurface on the dielectric rod is that it introduces an additional degree of freedom in the design of this antenna by controlling the outer boundary condition. Modified Generalized Sheet Transition Condition on a cylindrical geometry is used to model the metasurface on the dielectric rod. The analysis is based on developing the characteristic equation of the proposed structure. This characteristic equation is used to obtain the complex propagation constant of this structure and the corresponding field distribution inside and outside the rod including the resulting radiated fields. Parameters of the metasurface are extracted from the reflection and transmission properties of its elements in infinite periodic structure. An example of a dielectric rod loaded by a metasurface is presented analytically based on the introduced analysis and also simulated numerically for comparison. The effect of different polarizabilities of the loading metasurface on the leaky wave properties of the dielectric rod is discussed.

Progress in Electromagnetics Research M, 2020

A cosecant-squared radiation pattern synthesis for a planar antenna array by using the genetic al... more A cosecant-squared radiation pattern synthesis for a planar antenna array by using the genetic algorithm (GA) is presented. GA makes array synthesis flexible to achieve two desired features, namely, low peak side lobe level (PSLL) and small deviation (ripples) in the shaped beam region. In order to obtain a desired csc 2 pattern with the PSLL constrained, GA optimizes both the excitation amplitude and phase weights of the array elements. Dynamic range ratio (DRR) of the excitation amplitudes is improved by eliminating the weakly excited array elements from the optimized array without distorting the obtained pattern. To illustrate the effectiveness and advantages of GA, the beam pattern with specified characteristics is obtained for the same array by using particle swarm optimization (PSO). Results show that the performances of GA and PSO are comparable when dealing with small-tomoderate planar antenna arrays. However, GA significantly outperforms PSO on large arrays. Moreover, numerical results reveal that GA is superior to PSO in terms of cost function evaluation and statistical tests.

Progress in Electromagnetics Research M, 2020

The combination of low peak sidelobe level (PSLL) with wide sector nulling digital beamforming (D... more The combination of low peak sidelobe level (PSLL) with wide sector nulling digital beamforming (DBF) is achieved for large planar array antennas. This combination is carried out using the iterative Fourier transform (IFT) method. The method is based on the iterative Fourier technique to derive element excitations from the prescribed array factor using successive forward and backward Fourier transforms. A 1024-element rectangular uniformly spaced array is used as an example to demonstrate the performance of the proposed method. Numerical examples show that the proposed method achieves very low PSLL with very wide nulling sectors up to the half plane of the far-field pattern. Moreover, numerical results show that the proposed method is effectively functional even when the mainbeam is steered to directions other than the broadside.

2013 30th National Radio Science Conference (NRSC), 2013

Analysis and design of a coaxial leaky wave antenna with partially reflecting outer surface are p... more Analysis and design of a coaxial leaky wave antenna with partially reflecting outer surface are presented. The leaky wave properties are controlled by adjusting the surface impedance of the outer surface, the filling dielectric constant and the dimensions of the inner and outer radii. The required surface impedance of the outer surface is implemented by using periodic slits in a perfect conducting outer cylinder. Simple analytical form is used to obtain the dimensions of theses periodic slits. An example for designing a coaxial leaky wave antenna is discussed in detail and is also verified and tuned up by using full wave numerical simulation.

In this paper, a model is presented to simulate wave propagation in indoor corridors with partial... more In this paper, a model is presented to simulate wave propagation in indoor corridors with partially reflecting walls. The model is based on combination of modal analysis, dyadic Green's function, mode matching method and generalized scattering matrix. A new approach to simulate the effect of partial reflectivity of the walls of the waveguide model is proposed. This approach is based on approximating the fields inside the space of the actual waveguide section by equivalent waveguide sections of larger dimensions with PEC (Perfect Electric Conductor) walls. A simple scenario is considered in order to check the accuracy of this model. This scenario is verified by comparing experimental and numerical simulation results. The obtained results show that the proposed model is suitable for predicting accurate electric field strength due to an electromagnetic source in an indoor environment with partially reflecting boundaries.

Progress in Electromagnetics Research B, 2012

The problem of direction-of-arrival (DOA) estimation by using spectral search for a non-uniform p... more The problem of direction-of-arrival (DOA) estimation by using spectral search for a non-uniform planar array is addressed. New search methods for DOA estimation based on piecewise interpolation are proposed. The relationships between these methods and Fourier-Domain (FD) root-MUSIC are discussed. The proposed methods are based on dividing the multiple signal classification (MUSIC) null-spectrum function into a number of equal subintervals. These subintervals are interpolated by using low-degree polynomials. Piecewise interpolation methods based on elementary functions are used to reduce the required computations of MUSIC null-spectrum function. This property reduces the computational complexity compared with line-search methods for DOA estimation. The Cramér Rao Lower Bound (CRB) is used as a benchmark to check the accuracy and validity of the proposed methods.

Research Square (Research Square), Jan 23, 2023

A deep-learning-based model to automate the design of dual-band coupled-line trans-directional (C... more A deep-learning-based model to automate the design of dual-band coupled-line trans-directional (CL-TRD) coupler can greatly improve upon the current techniques that rely on complicated analysis. In this paper, we propose a convolutional neural network (CNN), which is a type of deep learning, which can rapidly output the parameters of dual-band directional couplers corresponding to theoretical (ideal) speci cations of the electrical parameters through an inverse model. The neural network training data is generated by the use of electromagnetic simulation tool HFSS by varying the geometrical design parameters of the coupler. In order to validate the robustness of the CNN inverse model, it is applied on a 3-dB dual-band CL-TRD coupler operating at 1.2/4 GHz, and compared with a shallow neural network namely, radial basis function neural network (RBFNN). The coupler parameters designed by both neural networks are veri ed by HFSS. The results reveal that the CNN simulated S-parameters and output ports phase difference are in good agreements with the ideal ones compared to those of RBFNN with more accuracy and speed. The designed coupler is fabricated and measured for veri cation.

Applied Computational Electromagnetics Society Journal, Dec 29, 2022

Tuning a microwave filter is a challenging problem due to its complexity. Extracting coupling mat... more Tuning a microwave filter is a challenging problem due to its complexity. Extracting coupling matrix from given S-parameters is essential for ?lter tuning and design. In this paper, a deep-learning-based neural network namely, a convolutional neural network (CNN) is proposed to extract coupling matrix from Sparameters of microwave filters. The training of the proposed CNN is based on a circuit model. In order to exhibit the robustness of the new technique, it is applied on 5-and 8-pole filters and compared with a shallow neural network namely, radial basis function neural network (RBFNN). The results reveal that the CNN can extract the coupling matrix of target S-parameters with high accuracy and speed.

In this paper, a model is presented to simulate wave propagation in indoor corridors and tunnels ... more In this paper, a model is presented to simulate wave propagation in indoor corridors and tunnels with imperfectly conducting walls. The model is based on the waveguiding effect of corridors and tunnels. This approach is based on assuming that the boundaries of the waveguide section are constant impedance surface as the surface impedance of the wall is almost independent of the angle of the wave incidence onto the wall. An analytical approach for the calculation of the signal correlation between the transmitters and receivers elements in tunnels and indoor corridors is proposed. A new approach for determining the best locations of the indoor access points is introduced based on minimum correlation between sources with minimum cross talk. A scenario is considered in order to check the accuracy of this model. This scenario is verified by comparing experimental and numerical simulation results. Good agreement is achieved.

ABSTRACT This paper presents the design of different types of chip-size antennas, which are suita... more ABSTRACT This paper presents the design of different types of chip-size antennas, which are suitable for wireless sensors such as a single frequency linear polarized antenna, a dual frequency antenna with linear polarization, and a single frequency circularly polarized antenna. The proposed antennas are used for short-range wireless microsystem applications and operate in 2.45 GHz and 5-6 GHz ISM bands. The fabrication and measurement of the single frequency linear polarized antenna are introduced.

Despite the advantages and importance of conventional linear regulators, low efficiency of about ... more Despite the advantages and importance of conventional linear regulators, low efficiency of about 40% is one of the main corresponding drawbacks. Supercapacitor assisted low dropout regulator (SCALDO), a linear DC to DC technique that can be used to duplicate efficiency. Therefore, supercapacitor is playing a crucial role to maximize the efficiency as a result of nearly lossless voltage dropper element, which minimize the losses in the pass element and power semiconductors. This work represents the mathematical principles of SCALDO and a simple implementation with simple and costly effective electronic components contrary to the traditional techniques. The proposed low dropout regulator is used to convert 12V to 5V. The linear regulator based on high efficiency SCALDO technique makes it appropriate for solar cell power systems applications.

Progress in Electromagnetics Research C, 2021

This paper presents a MIMO antenna system composed of eight wideband horizontal dualloop antenna ... more This paper presents a MIMO antenna system composed of eight wideband horizontal dualloop antenna elements. Each dual-loop antenna is printed on both sides of a smart phone board. The unit element antenna is designed to operate in the frequency range from 3.2 GHz to 5 GHz. The performance of the MIMO system is then analyzed. The performance of the obtained MIMO system in the frequency range from 3.2 GHz to 4.8 GHzis characterized by input reflection coefficient which is less than −6 dB for all antenna elements, and the isolation between the elements is larger than 15 dB. The total efficiency is greater than 55% over the entire band (3.2-4.8 GHz). Parameters of the multichannel antennas including envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CLL) are analyzed to evaluate the performance of the MIMO system. The effect of the human hand and head on the performance of this MIMO antenna is also investigated. In addition, the effect of the radiated fields on the human body is also studied. The Specific Absorption Rate (SAR) value is found to be less than 0.8 W/kg. The MIMO system antenna is fabricated and measured. Good agreements are obtained between the simulated and measured parameters. The proposed MIMO system is applicable to the 5G N48, N77, and N78 bands.

International Journal of Electrical and Computer Engineering, Apr 1, 2022

IEEE Access, 2022

This paper presents a wideband eight-port multiple-input-multiple-output (MIMO) circularly polari... more This paper presents a wideband eight-port multiple-input-multiple-output (MIMO) circularly polarized antenna system for mm-wave applications. The proposed antenna element is an L-shape microstrip line with a series fishtail stubs on one side. The spacing between these stubs is adjusted to be a guided wavelength at the center frequency. These fishtail stubs are used to cancel the anti-phase magnetic currents to enhance the radiated fields from the microstrip line. A 90 • phase difference between the fields of the two arms of the L-shape is obtained by shifting the feeding point from the center of the corner by one eighth guided wavelength. This 90 • phase difference introduces the required circular polarization. The proposed antenna covers the frequency range from 27.5 up to 31 GHz, which is suitable for mm-wave N261 5G-band which cover the range from 27.5 to 28.35 GHz. These antenna elements are arranged on the four corners of a rectangular substrate to configure the proposed MIMO antenna system. Different parameters of this MIMO antenna are investigated by using numerical simulation and verified by experimental results.

International Journal of Rf and Microwave Computer-aided Engineering, Jun 7, 2020

In this article the analysis and design of a dual circularly polarized 4 × 4 antenna array operat... more In this article the analysis and design of a dual circularly polarized 4 × 4 antenna array operating in Ku band are discussed with emphasis on its sequential feeding network. The proposed antenna element is composed of stacked circular patches fed by a branch line coupler to introduce dual circular polarization. These antenna elements are arranged into 2 × 2 sequential fed antenna arrays with two separate sequential feeding networks for LH and RH circular polarizations. These 2 × 2 sequential fed antenna arrays are arranged to compose the proposed 4 × 4 antenna array. The proposed feeding network is implements on a single layer. Due to the coupling between the lines of the complete feeding network, matching and axial ratio of the complete antenna are degraded. Matching stubs at appropriate points on the complete feeding network are used to adjust the total performance of the designed 4 × 4 antenna array. Simulation results by using both HFSS and CST are presented for comparison. In addition, experimental verifications are presented.

Progress in Electromagnetics Research C, 2023

In this paper, a new artificial magnetic conductor (AMC) structure is proposed to enhance the per... more In this paper, a new artificial magnetic conductor (AMC) structure is proposed to enhance the performance of an ultra-wideband (UWB) antenna for wireless communication networks. A fractal configuration is used to introduce the UWB performance of the proposed antenna. The antenna is composed of a modified rectangular patch antenna with a tapered section fed by a coplanar waveguide (CPW) with a total size of 24 × 20 × 1.5 mm 3. The antenna is backed by an AMC. The proposed AMC unit consists of a square patch surrounded by four slotted square rings. This unit cell exhibits an in-phase reflection from 6.3 GHz to 10 GHz. The obtained bandwidth of the antenna with AMC is 110% from 3.2 GHz to 11 GHz which covers the entire UWB range. The peak gain of 7.2 dB is accomplished with a compact size of 40 × 40 × 6.5 mm 3 , 0.95 × 0.95 × 0.15λ o at 7.1 GHz. The proposed UWB antenna-AMC is fabricated and measured for verification.

International Journal of Microwave and Wireless Technologies, Jul 5, 2021

Achieving robust and fast two-dimensional adaptive beamforming of phased array antennas is a chal... more Achieving robust and fast two-dimensional adaptive beamforming of phased array antennas is a challenging problem due to its high-computational complexity. To address this problem, a deep-learning-based beamforming method is presented in this paper. In particular, the optimum weight vector is computed by modeling the problem as a convolutional neural network (CNN), which is trained with I/O pairs obtained from the optimum Wiener solution. In order to exhibit the robustness of the new technique, it is applied on an 8 × 8 phased array antenna and compared with a shallow (non-deep) neural network namely, radial basis function neural network. The results reveal that the CNN leads to nearly optimal Wiener weights even in the presence of array imperfections.

This paper presents a new textile antenna for L1 GPS application. The textile antenna is based on... more This paper presents a new textile antenna for L1 GPS application. The textile antenna is based on a grounded flannel substrate (100% cotton). The designed textile fractal antenna is integrated with caps of different materials. The effect of the cap on the performance of the designed antenna is investigated. The textile antenna integrated with a cap is studied also in the presence of a human head to obtain the effect of the human head on the performance of the designed antenna. In addition the specific absorption rate (SAR) inside the human head due to the antenna is also studied.

Journal of Electromagnetic Waves and Applications, Jun 28, 2016

Abstract This paper introduces an analytical solution for a dielectric rod leaky wave antenna loa... more Abstract This paper introduces an analytical solution for a dielectric rod leaky wave antenna loaded by a metasurface. The advantage of adding metasurface on the dielectric rod is that it introduces an additional degree of freedom in the design of this antenna by controlling the outer boundary condition. Modified Generalized Sheet Transition Condition on a cylindrical geometry is used to model the metasurface on the dielectric rod. The analysis is based on developing the characteristic equation of the proposed structure. This characteristic equation is used to obtain the complex propagation constant of this structure and the corresponding field distribution inside and outside the rod including the resulting radiated fields. Parameters of the metasurface are extracted from the reflection and transmission properties of its elements in infinite periodic structure. An example of a dielectric rod loaded by a metasurface is presented analytically based on the introduced analysis and also simulated numerically for comparison. The effect of different polarizabilities of the loading metasurface on the leaky wave properties of the dielectric rod is discussed.

Progress in Electromagnetics Research M, 2020

A cosecant-squared radiation pattern synthesis for a planar antenna array by using the genetic al... more A cosecant-squared radiation pattern synthesis for a planar antenna array by using the genetic algorithm (GA) is presented. GA makes array synthesis flexible to achieve two desired features, namely, low peak side lobe level (PSLL) and small deviation (ripples) in the shaped beam region. In order to obtain a desired csc 2 pattern with the PSLL constrained, GA optimizes both the excitation amplitude and phase weights of the array elements. Dynamic range ratio (DRR) of the excitation amplitudes is improved by eliminating the weakly excited array elements from the optimized array without distorting the obtained pattern. To illustrate the effectiveness and advantages of GA, the beam pattern with specified characteristics is obtained for the same array by using particle swarm optimization (PSO). Results show that the performances of GA and PSO are comparable when dealing with small-tomoderate planar antenna arrays. However, GA significantly outperforms PSO on large arrays. Moreover, numerical results reveal that GA is superior to PSO in terms of cost function evaluation and statistical tests.

Progress in Electromagnetics Research M, 2020

The combination of low peak sidelobe level (PSLL) with wide sector nulling digital beamforming (D... more The combination of low peak sidelobe level (PSLL) with wide sector nulling digital beamforming (DBF) is achieved for large planar array antennas. This combination is carried out using the iterative Fourier transform (IFT) method. The method is based on the iterative Fourier technique to derive element excitations from the prescribed array factor using successive forward and backward Fourier transforms. A 1024-element rectangular uniformly spaced array is used as an example to demonstrate the performance of the proposed method. Numerical examples show that the proposed method achieves very low PSLL with very wide nulling sectors up to the half plane of the far-field pattern. Moreover, numerical results show that the proposed method is effectively functional even when the mainbeam is steered to directions other than the broadside.