Abdelghafour Abraray

@it.pt

Instituto de Telecomunicações, Universidade de Aveiro
Instituto de Telecomunicações

Abdelghafour Abraray


                     Download Compact PDF  
https://researchid.co/abdelghafour
Abdel Ghafour Abraray received BSc, MSc degrees from the physics faculty of Abdelmalek Essaadi University. (UAE), Tetuan, Morocco, in 2012 and 2014, respectively. In October 2016, he was accepted for the training period at the University of Coimbra in the framework of the Erasmus Mundus programme, for a period of 6 months. During the years 2017-2018, he was employed as a researcher under the project “Metamaterial superabsorbers for harnessing wireless power” at Instituto de Telecomunicações (IT), Coimbra, Portugal. In 2018-2019, he received a research grant (BI) at IT-Aveiro in the scope of the project “THz communication for beyond 5G Ultra-fast Networks”. Presently, he is a researcher in the project “Programmable Beamforming Metasurfaces” supervised by Dr. Stanislav Maslovski at Instituto de Telecomunicações, Aveiro. He is enrolled into the MAP-Tele Doctoral Programme in Telecommunications at the Departamento de Electrónica, Telecomunicações e Informática (DETI), Universidade do Aveir

EDUCATION

Abraray holds a Master's degree in Electronic and Telecommunication from the physics faculty of Abdelmalek Essaadi University. (UAE), Tetuan, Morocco
Recently he is a PhD student at the University of Aveiro.

RESEARCH, TEACHING, or OTHER INTERESTS

Engineering, Electrical and Electronic Engineering
19

Scopus Publications

67

Scholar Citations

5

Scholar h-index

Scopus Publications

  • Mechanically Reconfigurable GRIN Lens Concept for Focusing and Beamforming Applications
    K. Kaboutari, X. Liu, A. Abraray, P. Pinho, S. Shen, et al.
    Proceedings of the International Conference on Electromagnetics in Advanced Applications Iceaa, 2025
  • Numerically Optimized Fourier Transform-Based Beamforming Accelerated by Neural Networks
    Keivan Kaboutari, Abdelghafour Abraray, Stanislav Maslovski
    Applied Sciences Switzerland, 2024
    Conventional beamforming methods for reconfigurable reflector antennas assume full control over the amplitude and phase of the reflected field. Here, we develop a novel beamforming methodology for reflecting Programmable Metasurfaces (PMS) with capacitive memory. Although utilizing such fully reactive PMS simplifies antenna design and reduces energy consumption, the PMS reflection magnitude is unity and thus a global optimization of the reflection phases over the PMS unit cells is required in each beamforming scenario. We propose an implementation of such an optimization method rooted in the traditional Fourier transform-based beamforming and evaluate its performance. Additionally, we show that a pair of trained feed-forward neural networks (FFNN) with one input, one hidden, and one output layer can replace time-consuming global optimizations in the case of a PMS comprising 3×10 unit cells. We train the FFNNs on a dataset obtained for typical single- and dual-beam beamforming scenarios. After training, the FFNNs perform requested beamforming tasks within a fraction of second and with about the same accuracy as the original optimization algorithm. The proposed methodology may find applications in future mobile telecommunication systems that require real-time beamforming on low-end hardware. The same beamforming methodology can be also employed in short-range wireless power transfer systems.
  • Design of resonant metasurface absorber using feed-forward neural network
    Abdelghafour Abraray, Amit Baghel, Stanislav Maslovski
    Microwave and Optical Technology Letters, 2024
    In this work, an ultrathin ( mm) design of a frequency‐selective metamaterial absorber (MTA) is proposed. An absorption of 100% is achieved at the resonant frequency GHz with a fractional bandwidth of 1.45%. The MTA unit cell geometry is parametrized and modeled in a full‐wave electromagnetic simulator. Using a data set generated by varying the absorber unit cell geometry and simulating it in SIMULIA CST Studio Suite, the feed‐forward neural network is able to learn the relationship between the physical structure and its electromagnetic response. The numerical results for the MTA performance have been confirmed by an experiment. An array of 25 MTA elements in a configuration has been fabricated and tested in an anechoic chamber. The simulated and measured results are in a good agreement.
  • Impact of Phase Optimization on the Cascade Channel and System Performance of RIS-Assisted Wireless Networks
    Abdelghafour Abraray, Sherif A. Busari, Keivan Kaboutari, Jonathan Rodriguez, Stanislav I. Maslovski
    2024 International Microwave and Antenna Symposium Imas 2024, 2024
    In this work, we investigate the impacts of the Reconfigurable Intelligent Surface (RIS) phases or reflection matrix on the effective cascade (i.e., joint transmitter (TX)-to-RIS and RIS-to-receiver (RX)) channel and on the system performance for RIS-aided wireless networks. Using channel gain, signal-to-noise ratio and spectral efficiency as metrics, we demonstrate that our physical model-based RIS phases employing an optimized Fourier Transform (FT)-based beam-forming algorithm outperforms the cosine similarity (CS) phase algorithm. Unlike the CS algorithm where the RIS phases are deduced from the joint incident and reflected channel vectors, the optimized FT-based phases are blind to the cascade channels. We benchmark our results with random RIS phases as well as the mathematical upper bound. The results show that the FT phases outperform the CS and random phases, and approach the mathematical upper bound performance under diverse system parameters and configurations.
  • Reflective Metasurface Based on Embroidered Meander Resonators
    Abdelghafour Abraray, Marc Martíez-Estrada, Ignacio Gil, Nuno B. Carvalho, Stanislav I. Maslovski
    2024 International Microwave and Antenna Symposium Imas 2024, 2024
    This paper presents a concept of reflecting meta-surface (MS) with a novel unit cell design utilizing embroidered meander resonators. The resonators are formed by a silver-coated nylon thread embroidered on a felt textile substrate and have resonant frequencies around 3 GHz. Numerical simulations and experiments with prototypes have demonstrated that the proposed MS elements have a high and relatively broadband reflection greater than -5 dB in the range 2–4 GHz. Moreover, their resonance frequency can be changed within the same range by modifying the meander arm length. Reflecting MS formed by such elements can be fixed easily on a wall of a house or a tent in urban or rural environments and used as a passive Reflective Intelligent Surface (RIS) to facilitate mobile communications in areas like mountains and deserts. To the best of our knowledge, this paper demonstrates a possibility to use a fully textile MS element for this purpose for the first time.
  • PIN-diode controlled slot-fed MED antenna for 5G sub-6 GHz applications
    Keivan Kaboutari, Amir Siahcheshm, Majid Shokri, Zhale Amiri, Abdelghafour Abraray, et al.
    Proceedings of the International Conference on Electromagnetics in Advanced Applications Iceaa, 2024
    A new reconfigurable Magneto-Electric Dipole (MED) antenna with a slot feed for 5 G sub-6 GHz applications is designed using the “surrogateopt” optimization algorithm. The antenna covers the n78 and n79 frequency bands when a control PIN diode is in “on” and “off” states, respectively. Impedance matching of the proposed MED antenna is achieved by altering the slot width at its center. Full-wave numerical simulations have been conducted to optimize and verify the antenna performance. An equivalent circuit based on Schelkunoff’s theory for dipole antennas and the transmission line theory has been developed to model the antenna input impedance analytically. Both simulation and analytical modeling results show that the proposed reconfigurable MED antenna, with dimensions of $71 \\times 71 \\times 13.63 \\mathrm{~mm}^{3}$, fully covers the n78 and n79 bands and maintains stable gains above 7.6 dBi in these bands.
  • On Maximum Received Power in Rectenna Structures
    A. Abraray, T. R. Fernandes, S. I. Maslovski
    2023 Photonics and Electromagnetics Research Symposium Piers 2023 Proceedings, 2023
    The problem of maximization of the power received by an array of coupled compact antennas when connected to a number of loads through an optimal matching network is investigated both analytically and numerically. Theoretical results are obtained for the case of $N$ antennas connected to $M$ loads, and for $N$ antennas connected to a single load. A matching network between the antennas and the following stages, in this case a resistive load, has been designed in order to maximize the power harvested by the input antennas. The matching network is optimized to match the source and load impedances and to reduce the effect of mutual antenna coupling. As a specific example of a compact rectenna element, we consider a pair of coupled res-onant loop antennas with the geometry inspired by the well-known Split-Ring Resonator (SRR). We construct an optimal matching network for this structure based on the developed theory. Such application example featuring high mutual coupling in metamaterial-inspired rectennas is interesting from both theoretical and practical standpoints. To verify the theory, the antennas are simulated in SIMULIA CST Studio Suite. We compare the analytical and numerical results for such structures and make conclusions regarding the applicability and limitations of the developed theoretical framework.
  • Realization of Programmable Chessboard Mushroom-type Metasurface for Beamforming Applications
    A. Abraray, R. A. M. Pereira, K. Kaboutari, S. Maslovski
    2023 Photonics and Electromagnetics Research Symposium Piers 2023 Proceedings, 2023
    A reconfigurable microwave reflectarray metasurface (MS) is investigated for beamforming applications. The reflected beam direction is changed by applying external dc voltages, which create a reflection phase gradient on the structure. The studied MS comprises a chessboard-like array of metallic patches placed over a grounded dielectric slab with metallic vias connecting the patches to the controlling lines. Tunability is achieved with nonlinear capacitive loads (varactors) inserted between the corners of the metallic patches. The MS is studied analytically, numerically and experimentally, from which reshaping of the radiation pattern is observed according to the applied control voltages on the MS elements. The beamforming efficiency depends on the size of the MS and the beam width of the source antenna. It is shown that the proposed MS-based reflectarray with just 3-by-10 elements is already sufficient to redirect the beam in different directions.
  • Analytical and numerical modeling of reconfigurable reflecting metasurfaces with capacitive memory
    Abdelghafour Abraray, Diogo Nunes, Stanislav Maslovski
    New Journal of Physics, 2022
    In this article, we develop analytical–numerical models for reconfigurable reflecting metasurfaces (MSs) formed by chessboard-patterned arrays of metallic patches. These patch arrays are loaded with varactor diodes in order to enable surface impedance and reflection phase control. Two types of analytical models are considered. The first model based on the effective medium approach is used to predict the MS reflectivity. The second model is the Bloch wave dispersion model for the same structure understood as a two-dimensional transmission line metamaterial. The latter model is used to study ways to suppress parasitic resonances in finite-size beamforming MSs. We validate the developed analytical models with full-wave numerical simulations. Finally, we propose a design of the MS control network with capacitive memory that allows for independent programming of individual unit cells of the beamforming MS.
  • Programmable Chessboard Mushroom-Type Metasurface with Memory
    A. Abraray, S. Maslovski
    2021 15th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2021, 2021
    Here we propose and study a programmable metasurface (PMS) with analog memory that can be used for smart beamforming applications as well as for proactive control of the radio wave propagation environment. The operation of such PMS as a reconfigurable reflect-array is studied analytically and numerically. The PMS comprises a chess-board-like array of metallic patches placed over a dielectric slab with metallic vias connecting the patches to the controlling network. The network includes memory capacitors. The tunability is achieved with varactor loads placed at the corners of the patches. The proposed design has excellent angular stability of the resonant frequency for TE and TM polarizations. Analytical expressions are derived for the PMS surface impedance and reflection coefficient. The analytical results are verified with a number of numerical simulations.
  • Towards smart beamforming utilizing neural- networked programmable metasurfaces
    Abdelghafour Abraray, Antonio Navarro, Nuno Carvalho, Stanislav Maslovski
    2021 Telecoms Conference Conftele 2021, 2021
  • Beamforming with Intelligent Metasurfaces: Operating Principles and Possible Implementations
    Keivan Kaboutari, Abdelghafour Abraray, Stanislav Maslovski
    Proceedings of the 2021 International Conference on Electrical Engineering and Photonics Eexpolytech 2021, 2021
  • Analytical and Numerical Modeling of Reconfigurable Beamforming Metasurfaces
    S. Maslovski, A. Abraray, K. Kaboutari, D. Nunes, A. Navarro
    Progress in Electromagnetics Research Symposium, 2021
  • Beamforming with Neural-Networked Programmable Metasurfaces
    S. Maslovski, A. Abraray, N. Carvalho, A. Navarro
    2020 14th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2020, 2020
  • A metamaterial-inspired small rectenna for RF energy harvesting based on a 3-way power combiner
    Abdel-Ghafour Abraray, Kazi Mohammed Saidul Huq, Shahid Mumtaz, Jonathan Rodriguez, Otman El Mrabet, et al.
    Proceedings IEEE Global Communications Conference Globecom, 2019
  • Design and optimization of compact array rectennas for harvesting wireless power
    Iet Conference Publications, 2018
  • Conjugate impedance matched metamaterials: Physical modeling and wave interaction effects
    Stanislav I. Maslovski, Hugo R. L. Ferreira, Iurii O. Medvedev, Nuno G. B. Brás, Abdelghafour Abraray, et al.
    Journal of Physics Conference Series, 2018
  • A novel compact CPW OCSRR strucutre for 2.45 GHz rectenna application
    M. Bajtaoui, A. Abraray, O. EL Mrabet, Mariem Aznabet, M. Essaaidi
    Proceedings of 2016 International Renewable and Sustainable Energy Conference Irsec 2016, 2017
  • Design of a 5.8 GHZ rectenna by using metamaterial inspired small antenna
    A. Abraray, O. El Mrabet, A. Farkhsi, M. Aznabet, M. Bajtaoui, et al.
    International Conference on Multimedia Computing and Systems Proceedings, 2017

RECENT SCHOLAR PUBLICATIONS

  • Amplified up-conversion of electromagnetic waves using time-varying metasurfaces
    F Kovalev, S Maslovski, A Abraray, I Shadrivov
    arXiv preprint arXiv:2602.08193 , 2026
    2026
  • Mechanically Reconfigurable GRIN Lens Concept for Focusing and Beamforming Applications
    K Kaboutari, X Liu, A Abraray, P Pinho, S Shen, S Maslovski
    2025 International Conference on Electromagnetics in Advanced Applications … , 2025
    2025
  • Impact of Phase Optimization on the Cascade Channel and System Performance of RIS-Assisted Wireless Networks
    A Abraray, SA Busari, K Kaboutari, J Rodriguez, SI Maslovski
    2024 International Microwave and Antenna Symposium (IMAS), 1-4 , 2024
    2024
  • Reflective metasurface based on embroidered meander resonators
    A Abraray, M Martíez-Estrada, I Gil, NB Carvalho, SI Maslovski
    2024 International Microwave and Antenna Symposium (IMAS), 1-4 , 2024
    2024
  • PIN-diode controlled slot-fed MED antenna for 5G sub-6 GHz applications
    K Kaboutari, A Siahcheshm, M Shokri, Z Amiri, A Abraray, P Pinho, ...
    2024 international conference on electromagnetics in advanced applications … , 2024
    2024
    Citations: 6
  • Numerically optimized Fourier transform-based beamforming accelerated by neural networks
    K Kaboutari, A Abraray, S Maslovski
    Applied Sciences 14 (7), 2866 , 2024
    2024
    Citations: 5
  • Design of resonant metasurface absorber using feed‐forward neural network
    A Abraray, A Baghel, S Maslovski
    Microwave and Optical Technology Letters 66 (1), e33977 , 2024
    2024
    Citations: 4
  • Realization of programmable chessboard mushroom-type metasurface for beamforming applications
    A Abraray, RAM Pereira, K Kaboutari, S Maslovski
    2023 Photonics & Electromagnetics Research Symposium (PIERS), 1909-1913 , 2023
    2023
    Citations: 5
  • On Maximum Received Power in Rectenna Structures
    A Abraray, TR Fernandes, SI Maslovski
    2023 Photonics & Electromagnetics Research Symposium (PIERS), 889-896 , 2023
    2023
  • Analytical and numerical modeling of reconfigurable reflecting metasurfaces with capacitive memory
    A Abraray, D Nunes, S Maslovski
    New Journal of Physics 24 (7), 075003 , 2022
    2022
    Citations: 8
  • Chessboard Mushroom-Type Metasurface for Beamforming Applications
    A Abraray, R Pereira, K Kaboutari, S Maslovski
    arXiv preprint arXiv:2205.14671 , 2022
    2022
  • Analytical and numerical modeling of reconfigurable beamforming metasurfaces
    S Maslovski, A Abraray, K Kaboutari, D Nunes, A Navarro
    2021 Photonics & Electromagnetics Research Symposium (PIERS), 2637-2647 , 2021
    2021
    Citations: 6
  • Beamforming with Intelligent Metasurfaces: Operating Principles and Possible Implementations
    K Kaboutari, A Abraray, S Maslovski
    2021 International Conference on Electrical Engineering and Photonics … , 2021
    2021
    Citations: 5
  • Programmable chessboard Mushroom-type metasurface with memory
    A Abraray, S Maslovski
    2021 Fifteenth International Congress on Artificial Materials for Novel Wave … , 2021
    2021
    Citations: 3
  • Towards smart beamforming utilizing neural-networked programmable metasurfaces
    A Abraray, A Navarro, N Carvalho, S Maslovski
    2021 Telecoms Conference (ConfTELE), 1-6 , 2021
    2021
    Citations: 8
  • Beamforming with Neural-Networked Programmable Metasurfaces
    S Maslovski, A Abraray, N Carvalho, A Navarro
    2020 Fourteenth International Congress on Artificial Materials for Novel … , 2020
    2020
    Citations: 4
  • A metamaterial-inspired small rectenna for RF energy harvesting based on a 3-way power combiner
    AG Abraray, KMS Huq, S Mumtaz, J Rodriguez, O El Mrabet, A Farkhsi, ...
    2019 IEEE Global Communications Conference (GLOBECOM), 1-6 , 2019
    2019
    Citations: 3
  • Design and optimization of compact array rectennas for harvesting wireless power
    AG Abraray, TR Fernandes, SI Maslovski
    Loughborough Antennas & Propagation Conference 2018 (LAPC 2018), 64 , 2018
    2018
    Citations: 5
  • Conjugate impedance matched metamaterials: Physical modeling and wave interaction effects
    SI Maslovski, HRL Ferreira, IO Medvedev, NGB Brás, A Abraray, ...
    Journal of Physics: Conference Series 1092 (1), 012084 , 2018
    2018
    Citations: 1
  • A novel compact CPW OCSRR strucutre for 2.45 GHz rectenna application
    M Bajtaoui, A Abraray, OEL Mrabet, M Aznabet, M Essaaidi
    2016 International Renewable and Sustainable Energy Conference (IRSEC), 979-982 , 2016
    2016

MOST CITED SCHOLAR PUBLICATIONS

  • Analytical and numerical modeling of reconfigurable reflecting metasurfaces with capacitive memory
    A Abraray, D Nunes, S Maslovski
    New Journal of Physics 24 (7), 075003 , 2022
    2022
    Citations: 8
  • Towards smart beamforming utilizing neural-networked programmable metasurfaces
    A Abraray, A Navarro, N Carvalho, S Maslovski
    2021 Telecoms Conference (ConfTELE), 1-6 , 2021
    2021
    Citations: 8
  • PIN-diode controlled slot-fed MED antenna for 5G sub-6 GHz applications
    K Kaboutari, A Siahcheshm, M Shokri, Z Amiri, A Abraray, P Pinho, ...
    2024 international conference on electromagnetics in advanced applications … , 2024
    2024
    Citations: 6
  • Analytical and numerical modeling of reconfigurable beamforming metasurfaces
    S Maslovski, A Abraray, K Kaboutari, D Nunes, A Navarro
    2021 Photonics & Electromagnetics Research Symposium (PIERS), 2637-2647 , 2021
    2021
    Citations: 6
  • Numerically optimized Fourier transform-based beamforming accelerated by neural networks
    K Kaboutari, A Abraray, S Maslovski
    Applied Sciences 14 (7), 2866 , 2024
    2024
    Citations: 5
  • Realization of programmable chessboard mushroom-type metasurface for beamforming applications
    A Abraray, RAM Pereira, K Kaboutari, S Maslovski
    2023 Photonics & Electromagnetics Research Symposium (PIERS), 1909-1913 , 2023
    2023
    Citations: 5
  • Beamforming with Intelligent Metasurfaces: Operating Principles and Possible Implementations
    K Kaboutari, A Abraray, S Maslovski
    2021 International Conference on Electrical Engineering and Photonics … , 2021
    2021
    Citations: 5
  • Design and optimization of compact array rectennas for harvesting wireless power
    AG Abraray, TR Fernandes, SI Maslovski
    Loughborough Antennas & Propagation Conference 2018 (LAPC 2018), 64 , 2018
    2018
    Citations: 5
  • Design of resonant metasurface absorber using feed‐forward neural network
    A Abraray, A Baghel, S Maslovski
    Microwave and Optical Technology Letters 66 (1), e33977 , 2024
    2024
    Citations: 4
  • Beamforming with Neural-Networked Programmable Metasurfaces
    S Maslovski, A Abraray, N Carvalho, A Navarro
    2020 Fourteenth International Congress on Artificial Materials for Novel … , 2020
    2020
    Citations: 4
  • Design of a 5.8 GHZ rectenna by using metamaterial inspired small antenna
    A Abraray, O El Mrabet, A Farkhsi, M Aznabet, M Bajtaoui, B El Jaafari, ...
    2016 5th International Conference on Multimedia Computing and Systems (ICMCS … , 2016
    2016
    Citations: 4
  • Programmable chessboard Mushroom-type metasurface with memory
    A Abraray, S Maslovski
    2021 Fifteenth International Congress on Artificial Materials for Novel Wave … , 2021
    2021
    Citations: 3
  • A metamaterial-inspired small rectenna for RF energy harvesting based on a 3-way power combiner
    AG Abraray, KMS Huq, S Mumtaz, J Rodriguez, O El Mrabet, A Farkhsi, ...
    2019 IEEE Global Communications Conference (GLOBECOM), 1-6 , 2019
    2019
    Citations: 3
  • Conjugate impedance matched metamaterials: Physical modeling and wave interaction effects
    SI Maslovski, HRL Ferreira, IO Medvedev, NGB Brás, A Abraray, ...
    Journal of Physics: Conference Series 1092 (1), 012084 , 2018
    2018
    Citations: 1
  • Amplified up-conversion of electromagnetic waves using time-varying metasurfaces
    F Kovalev, S Maslovski, A Abraray, I Shadrivov
    arXiv preprint arXiv:2602.08193 , 2026
    2026
  • Mechanically Reconfigurable GRIN Lens Concept for Focusing and Beamforming Applications
    K Kaboutari, X Liu, A Abraray, P Pinho, S Shen, S Maslovski
    2025 International Conference on Electromagnetics in Advanced Applications … , 2025
    2025
  • Impact of Phase Optimization on the Cascade Channel and System Performance of RIS-Assisted Wireless Networks
    A Abraray, SA Busari, K Kaboutari, J Rodriguez, SI Maslovski
    2024 International Microwave and Antenna Symposium (IMAS), 1-4 , 2024
    2024
  • Reflective metasurface based on embroidered meander resonators
    A Abraray, M Martíez-Estrada, I Gil, NB Carvalho, SI Maslovski
    2024 International Microwave and Antenna Symposium (IMAS), 1-4 , 2024
    2024
  • On Maximum Received Power in Rectenna Structures
    A Abraray, TR Fernandes, SI Maslovski
    2023 Photonics & Electromagnetics Research Symposium (PIERS), 889-896 , 2023
    2023
  • Chessboard Mushroom-Type Metasurface for Beamforming Applications
    A Abraray, R Pereira, K Kaboutari, S Maslovski
    arXiv preprint arXiv:2205.14671 , 2022
    2022