Eduardo Carrasco - Academia.edu (original) (raw)
Papers by Eduardo Carrasco
Zenodo (CERN European Organization for Nuclear Research), Jul 29, 2022
This deliverable presents the scenarios that will be showcased in the proof-of-concept demonstrat... more This deliverable presents the scenarios that will be showcased in the proof-of-concept demonstrators addressing key ARIADNE targets, as well as the plans for the setup of the relevant testbeds. The two hardware demonstrators will use the development work of WP3, while the work outcomes of WP4 will be the keystone for the software demonstrator. The described scenarios and implementation plans will be the blueprint for the system integration and the demonstration activities that will follow. Impressum Full project title: Artificial Intelligence Aided D-band Network for 5G Long Term Evolution Short project title: ARIADNE Number and title of work-package: WP5-Demonstration of Intelligent D-Band Network Number and title of task: Task 5.1-Definition of demonstration scenarios and performance evaluation Document title: Report on the demonstration scenarios and description of testbed implementation plan
arXiv (Cornell University), Apr 16, 2013
In this opening presentation we will first recall the main characteristics of graphene conductivi... more In this opening presentation we will first recall the main characteristics of graphene conductivity and electromagnetic wave propagation on graphene-based structures. Based on these observations and different graphene antenna simulations from microwave to terahertz, we will discuss the issue of antenna efficiency, integration and reconfigurability, as function of the operation frequency range. While the use of graphene for antennas at microwave appears extremely limited, the plasmonic nature of graphene conductivity at terahertz frequency allows unprecedented antenna properties and in particular efficient dynamic reconfiguration.
Zenodo (CERN European Organization for Nuclear Research), May 30, 2022
This deliverable summarizes the research on D-band radio concepts of ARIADNE, as an output of the... more This deliverable summarizes the research on D-band radio concepts of ARIADNE, as an output of the first 30 months of work in Tasks 3.1-3.4. Deliverable D3.3 reinforces, generalizes and expands the results of the research activities conducted and settled as plan in Deliverable D3.1 on "Report on baseband and antenna concepts" and Deliverable D3.2 "Report on simulations of first RFIC implementations". In this direction the present deliverable focuses on baseband design and prototypes, on antennas design and prototypes for short and long range scenarios (outdoor and indoor) and on metasurfaces/RIS design and manufacture to assist mainly indoor communications. Coordinator of this deliverable is NCSRD. Technical contributors are all partners of the work package. The technical quality is assured by the technical management UPRC Prof. Angela Alexiou, the WP Leader IAF and the Task Leaders ICOM (Task 3.1), IAF (Task 3.2), NCSRD (Task 3.3), and AALTO (Task 3.4). Disclaimer This document contains material, which is the copyright of certain ARIADNE consortium parties, and may not be reproduced or copied without permission. All ARIADNE consortium parties have agreed to full publication of this document. Neither the ARIADNE consortium as a whole, nor a certain part of the ARIADNE consortium, warrant that the information contained in this document is capable of use, nor that use of the information is free from risk, accepting no liability for loss or damage suffered by any person using this information.
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA)
A dual-frequency reflectarray cell is proposed in this work to provide a progressive phase shift ... more A dual-frequency reflectarray cell is proposed in this work to provide a progressive phase shift of opposite sign in each circular polarization (CP), by applying a variable rotation technique (VRT) [1], The proposed reflectarray cell consists of two symmetrical arcs printed on the top surface and two orthogonal sets of parallel dipoles printed on two levels of a grounded dielectric substrate, see Figure 1. The arcs and dipoles are rotated independently to control the phase in CP at the lower (19.7 GHz) and higher (29.5 GHz) frequencies respectively. This reflectarray cell can be used to generate two adjacent beams in orthogonal CP per feed at transmission (Tx) and reception (Rx), in order to reduce the number of feeds and antennas required in current multi-spot satellites operating in Ka-band, as proposed in [1] for a single frequency band.
International Journal of Microwave and Wireless Technologies
This paper presents the design of two passive shaped-beam reflectarrays acting as passive intelli... more This paper presents the design of two passive shaped-beam reflectarrays acting as passive intelligent reflecting surfaces (IRSs) to enhance 5G millimeter-wave coverage in the 27.2–28.2 GHz band. The reflectarray panels have been designed to generate a broadened and deflected beam in dual-linear polarization (horizontal and vertical). The reflectarray cell provides a robust performance under incidence angles of up to 50°, with more than 360° of phase variation range. Phase-only synthesis based on the generalized intersection approach has been applied to obtain the phase distribution on each reflectarray panel, so that their radiation patterns comply with the beamwidth and pointing requirements of the scenario under study. The two reflectarrays show a stable performance in the 27.2–28.2 GHz band in terms of gain, side-lobe level, and cross-polarization. The results confirm the potential of this technology to implement passive low-cost IRSs that will contribute to improve millimeter-wa...
This deliverable describes the D-band transceiver RFICs, which were planned and designed as part ... more This deliverable describes the D-band transceiver RFICs, which were planned and designed as part of the first project phase between M12 and M17. Prior work for this activity explored some test structures for developing mixed-signal functions at the later stage, as well as breakout circuits and test packages for some critical transceiver functions for risk mitigation during the first year of the project. The fabrication, testing and packaging of the transceiver chipset is part of the second year, followed by the integration into an outdoor unit for the first field trials in ARIANDE. The main objective of this deliverable is to provide an overview of the RFIC chipset that will also serve as the baseline for further research in ARIADNE on energy efficient D-band transceivers as well as front-end management and control interfaces needed for that purpose.<br> Coordinator and technical contributor of this deliverable is IAF. The technical quality is assured by the technical manager ...
1 Formerly with the Adaptive MicroNano Wave Systems group, (EPFL), currently Antenna Consultant, ... more 1 Formerly with the Adaptive MicroNano Wave Systems group, (EPFL), currently Antenna Consultant, Spain/Switzerland 2 Adaptive MicroNano Wave Systems group, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland 3 Laboratory of Electromagnetics and Acoustics (LEMA), Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland 4 Department of Physics & Electrical Engineering, Columbia University, USA 5 Department of Electrical & Computer Engineering, University of Minnesota, USA
2021 15th European Conference on Antennas and Propagation (EuCAP), 2021
This contribution presents the design of a passive shaped-beam reflectarray to improve coverage i... more This contribution presents the design of a passive shaped-beam reflectarray to improve coverage in 5G cellular networks. The reflectarray has been designed to produce a broadened and deflected beam in dual-linear polarization at 27.7 GHz. The unit cell provides more than 360º range of phase variation and a robust performance under large angles of incidence (around 50º). Phase-only synthesis has been applied to obtain the required phase distribution on the reflectarray to fulfill the scenario requirements in terms of beam pointing and HPBW. The designed reflectarray exhibits a stable behavior within the 27.2-28.2 GHz band, showing the potential of this technology for millimeter-wave 5G communications.
IEEE Access, 2020
The analysis and design of reflectarray (RA) antennas based in delay lines is introduced for the ... more The analysis and design of reflectarray (RA) antennas based in delay lines is introduced for the first time from a filter perspective. To this purpose, each unit-cell of the RA is considered as a network composed of two ports, one being the delay line and the other one the free-space. This approach allows to borrow the coupling matrix formalism from filter theory and apply it to design unit-cells exhibiting broadband operation together with very sharp frequency responses. The concept is demonstrated with the aid of planar printed unit-cells coupled to substrate integrated waveguides (SIWs) through slots, a configuration that offers significant advantages to shape its frequency response while providing relatively low loss. With the aim of validation, a third order filter structure integrated in SIW-based unit-cells has been experimentally tested using the waveguide simulator technique, at a center frequency of 9 GHz. Measurements demonstrate a high-quality linear phase variation and range, and large frequency selectivity together with broadband response for the element of about 18%. The experimental results show the feasibility of this approach for the design of broadband reflectarray antennas exhibiting sharp gain responses. To illustrate the concept, a medium size reflectarray has been theoretically designed using the proposed unit cell at 9 GHz, showing a directive beam with 35.8 dB gain, sharp gain selectivity over 18 dB, and confirms the wide band operation with 20.3% bandwidth for a 3 dB gain variation. INDEX TERMS Broadband antennas, delay-line elements, filter theory, gain selectivity, reflectarray antennas, substrate integrated waveguide.
Nanotechnology, 2015
Graphene plasmonic nanostructures enable subwavelength confinement of electromagnetic energy from... more Graphene plasmonic nanostructures enable subwavelength confinement of electromagnetic energy from the mid-infrared down to the terahertz frequencies. By exploiting the spectrally varying light scattering phase at vicinity of the resonant frequency of the plasmonic nanostructure, it is possible to control the angle of reflection of an incoming light beam. We demonstrate, through full-wave electromagnetic simulations based on Maxwell equations, the electrical control of the angle of reflection of a mid-infrared light beam by using an aperiodic array of graphene nanoribbons, whose widths are engineered to produce a spatially varying reflection phase profile that allows for the construction of a far-field collimated beam towards a predefined direction.
2010 IEEE Antennas and Propagation Society International Symposium, 2010
An offset dual reflector antenna using a reflectarray subreflector and a parabolic main reflector... more An offset dual reflector antenna using a reflectarray subreflector and a parabolic main reflector has been proposed for beam steering in a limited range by implementing a progressive phase on the sub-reflectarray [1]. This antenna configuration combines the high gain capabilities ...
Microwave and Optical Technology Letters, 2014
A broadband reflectarray cell made of three parallel dipoles printed on a dielectric layer is pre... more A broadband reflectarray cell made of three parallel dipoles printed on a dielectric layer is presented. A 33% bandwidth is achieved for the cell made of dipoles, which is larger than that obtained for a reference cell consisting of three stacked square patches (26%). Using this cell, a 41-cm reflectarray antenna has been designed to produce a collimated beam at 9.5 GHz. The numerical results obtained for the reflectarray antenna made of parallel dipoles show a 1-dB bandwidth of 19%, a 65% efficiency, 0.2 dB of losses, and low levels of cross polarization (25 dB below the maximum). These results demonstrate a high performance for the proposed reflectarray antenna made of cells with three printed dipoles.
International Journal of Antennas and Propagation, 2012
Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both du... more Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both dual-reflector antenna with a reflectarray subreflector and dual-reflectarrays antennas with flat or parabolic main reflectarray are considered. First, a general analysis technique for these two configurations is described. Second, results for beam scanning and contoured-beam applications in different frequency bands are shown and discussed. The performance and capabilities of these antennas are shown by describing some practical design cases for radar, satellite communications, and direct broadcast satellite (DBS) applications.
IEEE Transactions on Antennas and Propagation, 2008
A shaped-beam reflectarray based on patches, aperture-coupled to delay lines is demonstrated for ... more A shaped-beam reflectarray based on patches, aperture-coupled to delay lines is demonstrated for local multipoint distribution system (LMDS) central station antennas, in the 10.10-10.70 GHz band. The antenna must cover a 60°-sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the square patches, in order to achieve the phase distribution synthesized in the previous step. Two reflectarray antennas have been designed, one for vertical (V) and the other for horizontal (H) polarization. A breadboard for V-polarization has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.
IEEE Transactions on Antennas and Propagation, 2008
A significant improvement in the bandwidth of large reflectarrays is demonstrated using elements ... more A significant improvement in the bandwidth of large reflectarrays is demonstrated using elements which allow true-time delay. Two identical, large reflectarrays have been designed using different phase distributions to generate a collimated beam. In the former, the phase distribution is truncated to 360° as is usual in reflectarray antennas, while in the second, the true phase delay is maintained (three cycles of 360°). The chosen phase-shifter elements are based on previously measured and validated patches aperture-coupled to delay lines. The radiation patterns for both reflectarrays have been computed at several frequencies and the gain is represented as a function of frequency for both cases. Bandwidth curves are presented as a function of the reflectarray size.
Applied Physics Letters, 2013
A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-b... more A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-beam reflectarrays, or similarly to implement the so-called generalized law of reflection. The change in the complex conductivity of graphene when biased by an electric field allows controlling the phase of the reflected field at each element of the array. Additionally, the slow wave propagation supported by graphene drastically reduces the dimensions of the cell, which allows smaller inter-element spacing hence better array performance. An elementary cell is optimized and its scattering parameters computed, demonstrating a dynamic phase range of 300° and good loss figure for realistic chemical potential variations. Finally, a circuit model is proposed and shown to very accurately predict the element response.
In this work, the authors compare two designs of reflectarray antennas made of two different type... more In this work, the authors compare two designs of reflectarray antennas made of two different types of elements. One of the reflectarray designs is intended to generate a collimated beam and the other is intended to generate a contoured beam. In order to produce these radiation patterns, in one case three coplanar parallel dipoles are used as reflectarray elements, and in the other case stacked square patches are used as reflectarray elements. The results obtained indicate that the collimated beam and shaped beam reflectarrays made of parallel dipoles have a good bandwidth performance, which is comparable to that of the collimated beam and shaped beam reflectarrays made of stacked patches. However, the reflectarrays made of parallel dipoles achieve the broadband goal with a manufacturing process that is easier and cheaper than that required by the reflectarrays made of stacked patches.
A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station a... more A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station antenna for Local Multipoint Distribution System (LMDS) in the 10.10-10.70 GHz band. The antenna must cover a 60° sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the squared patches, in order to achieve the phase distribution synthesized in the previous step. A reflectarray antenna has been designed for vertical (V) polarization. A breadboard has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.
IEEE Antennas and Wireless Propagation Letters, 2019
A new reflectarray cell is proposed to simultaneously provide opposite phase shifts between ortho... more A new reflectarray cell is proposed to simultaneously provide opposite phase shifts between orthogonal circular polarizations at two frequencies (19.7 and 29.5 GHz) by applying a variable rotation technique independently at each frequency. The reflectarray cell, which consists of two dielectric layers with two levels of printed elements (dipoles and arcs), has been characterized for both circular and linear polarizations at each frequency. Apart from the implementation of the variable rotation technique at each frequency, the reflectarray cell provides an additional phase adjustment at the higher frequency, which can be used to shape the beam. This concept applied to multiple spot satellites in ÍTa-band will allow to produce two adjacent beams per feed in orthogonal circular polarizations at transmission and reception frequency bands.
Zenodo (CERN European Organization for Nuclear Research), Jul 29, 2022
This deliverable presents the scenarios that will be showcased in the proof-of-concept demonstrat... more This deliverable presents the scenarios that will be showcased in the proof-of-concept demonstrators addressing key ARIADNE targets, as well as the plans for the setup of the relevant testbeds. The two hardware demonstrators will use the development work of WP3, while the work outcomes of WP4 will be the keystone for the software demonstrator. The described scenarios and implementation plans will be the blueprint for the system integration and the demonstration activities that will follow. Impressum Full project title: Artificial Intelligence Aided D-band Network for 5G Long Term Evolution Short project title: ARIADNE Number and title of work-package: WP5-Demonstration of Intelligent D-Band Network Number and title of task: Task 5.1-Definition of demonstration scenarios and performance evaluation Document title: Report on the demonstration scenarios and description of testbed implementation plan
arXiv (Cornell University), Apr 16, 2013
In this opening presentation we will first recall the main characteristics of graphene conductivi... more In this opening presentation we will first recall the main characteristics of graphene conductivity and electromagnetic wave propagation on graphene-based structures. Based on these observations and different graphene antenna simulations from microwave to terahertz, we will discuss the issue of antenna efficiency, integration and reconfigurability, as function of the operation frequency range. While the use of graphene for antennas at microwave appears extremely limited, the plasmonic nature of graphene conductivity at terahertz frequency allows unprecedented antenna properties and in particular efficient dynamic reconfiguration.
Zenodo (CERN European Organization for Nuclear Research), May 30, 2022
This deliverable summarizes the research on D-band radio concepts of ARIADNE, as an output of the... more This deliverable summarizes the research on D-band radio concepts of ARIADNE, as an output of the first 30 months of work in Tasks 3.1-3.4. Deliverable D3.3 reinforces, generalizes and expands the results of the research activities conducted and settled as plan in Deliverable D3.1 on "Report on baseband and antenna concepts" and Deliverable D3.2 "Report on simulations of first RFIC implementations". In this direction the present deliverable focuses on baseband design and prototypes, on antennas design and prototypes for short and long range scenarios (outdoor and indoor) and on metasurfaces/RIS design and manufacture to assist mainly indoor communications. Coordinator of this deliverable is NCSRD. Technical contributors are all partners of the work package. The technical quality is assured by the technical management UPRC Prof. Angela Alexiou, the WP Leader IAF and the Task Leaders ICOM (Task 3.1), IAF (Task 3.2), NCSRD (Task 3.3), and AALTO (Task 3.4). Disclaimer This document contains material, which is the copyright of certain ARIADNE consortium parties, and may not be reproduced or copied without permission. All ARIADNE consortium parties have agreed to full publication of this document. Neither the ARIADNE consortium as a whole, nor a certain part of the ARIADNE consortium, warrant that the information contained in this document is capable of use, nor that use of the information is free from risk, accepting no liability for loss or damage suffered by any person using this information.
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA)
A dual-frequency reflectarray cell is proposed in this work to provide a progressive phase shift ... more A dual-frequency reflectarray cell is proposed in this work to provide a progressive phase shift of opposite sign in each circular polarization (CP), by applying a variable rotation technique (VRT) [1], The proposed reflectarray cell consists of two symmetrical arcs printed on the top surface and two orthogonal sets of parallel dipoles printed on two levels of a grounded dielectric substrate, see Figure 1. The arcs and dipoles are rotated independently to control the phase in CP at the lower (19.7 GHz) and higher (29.5 GHz) frequencies respectively. This reflectarray cell can be used to generate two adjacent beams in orthogonal CP per feed at transmission (Tx) and reception (Rx), in order to reduce the number of feeds and antennas required in current multi-spot satellites operating in Ka-band, as proposed in [1] for a single frequency band.
International Journal of Microwave and Wireless Technologies
This paper presents the design of two passive shaped-beam reflectarrays acting as passive intelli... more This paper presents the design of two passive shaped-beam reflectarrays acting as passive intelligent reflecting surfaces (IRSs) to enhance 5G millimeter-wave coverage in the 27.2–28.2 GHz band. The reflectarray panels have been designed to generate a broadened and deflected beam in dual-linear polarization (horizontal and vertical). The reflectarray cell provides a robust performance under incidence angles of up to 50°, with more than 360° of phase variation range. Phase-only synthesis based on the generalized intersection approach has been applied to obtain the phase distribution on each reflectarray panel, so that their radiation patterns comply with the beamwidth and pointing requirements of the scenario under study. The two reflectarrays show a stable performance in the 27.2–28.2 GHz band in terms of gain, side-lobe level, and cross-polarization. The results confirm the potential of this technology to implement passive low-cost IRSs that will contribute to improve millimeter-wa...
This deliverable describes the D-band transceiver RFICs, which were planned and designed as part ... more This deliverable describes the D-band transceiver RFICs, which were planned and designed as part of the first project phase between M12 and M17. Prior work for this activity explored some test structures for developing mixed-signal functions at the later stage, as well as breakout circuits and test packages for some critical transceiver functions for risk mitigation during the first year of the project. The fabrication, testing and packaging of the transceiver chipset is part of the second year, followed by the integration into an outdoor unit for the first field trials in ARIANDE. The main objective of this deliverable is to provide an overview of the RFIC chipset that will also serve as the baseline for further research in ARIADNE on energy efficient D-band transceivers as well as front-end management and control interfaces needed for that purpose.<br> Coordinator and technical contributor of this deliverable is IAF. The technical quality is assured by the technical manager ...
1 Formerly with the Adaptive MicroNano Wave Systems group, (EPFL), currently Antenna Consultant, ... more 1 Formerly with the Adaptive MicroNano Wave Systems group, (EPFL), currently Antenna Consultant, Spain/Switzerland 2 Adaptive MicroNano Wave Systems group, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland 3 Laboratory of Electromagnetics and Acoustics (LEMA), Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland 4 Department of Physics & Electrical Engineering, Columbia University, USA 5 Department of Electrical & Computer Engineering, University of Minnesota, USA
2021 15th European Conference on Antennas and Propagation (EuCAP), 2021
This contribution presents the design of a passive shaped-beam reflectarray to improve coverage i... more This contribution presents the design of a passive shaped-beam reflectarray to improve coverage in 5G cellular networks. The reflectarray has been designed to produce a broadened and deflected beam in dual-linear polarization at 27.7 GHz. The unit cell provides more than 360º range of phase variation and a robust performance under large angles of incidence (around 50º). Phase-only synthesis has been applied to obtain the required phase distribution on the reflectarray to fulfill the scenario requirements in terms of beam pointing and HPBW. The designed reflectarray exhibits a stable behavior within the 27.2-28.2 GHz band, showing the potential of this technology for millimeter-wave 5G communications.
IEEE Access, 2020
The analysis and design of reflectarray (RA) antennas based in delay lines is introduced for the ... more The analysis and design of reflectarray (RA) antennas based in delay lines is introduced for the first time from a filter perspective. To this purpose, each unit-cell of the RA is considered as a network composed of two ports, one being the delay line and the other one the free-space. This approach allows to borrow the coupling matrix formalism from filter theory and apply it to design unit-cells exhibiting broadband operation together with very sharp frequency responses. The concept is demonstrated with the aid of planar printed unit-cells coupled to substrate integrated waveguides (SIWs) through slots, a configuration that offers significant advantages to shape its frequency response while providing relatively low loss. With the aim of validation, a third order filter structure integrated in SIW-based unit-cells has been experimentally tested using the waveguide simulator technique, at a center frequency of 9 GHz. Measurements demonstrate a high-quality linear phase variation and range, and large frequency selectivity together with broadband response for the element of about 18%. The experimental results show the feasibility of this approach for the design of broadband reflectarray antennas exhibiting sharp gain responses. To illustrate the concept, a medium size reflectarray has been theoretically designed using the proposed unit cell at 9 GHz, showing a directive beam with 35.8 dB gain, sharp gain selectivity over 18 dB, and confirms the wide band operation with 20.3% bandwidth for a 3 dB gain variation. INDEX TERMS Broadband antennas, delay-line elements, filter theory, gain selectivity, reflectarray antennas, substrate integrated waveguide.
Nanotechnology, 2015
Graphene plasmonic nanostructures enable subwavelength confinement of electromagnetic energy from... more Graphene plasmonic nanostructures enable subwavelength confinement of electromagnetic energy from the mid-infrared down to the terahertz frequencies. By exploiting the spectrally varying light scattering phase at vicinity of the resonant frequency of the plasmonic nanostructure, it is possible to control the angle of reflection of an incoming light beam. We demonstrate, through full-wave electromagnetic simulations based on Maxwell equations, the electrical control of the angle of reflection of a mid-infrared light beam by using an aperiodic array of graphene nanoribbons, whose widths are engineered to produce a spatially varying reflection phase profile that allows for the construction of a far-field collimated beam towards a predefined direction.
2010 IEEE Antennas and Propagation Society International Symposium, 2010
An offset dual reflector antenna using a reflectarray subreflector and a parabolic main reflector... more An offset dual reflector antenna using a reflectarray subreflector and a parabolic main reflector has been proposed for beam steering in a limited range by implementing a progressive phase on the sub-reflectarray [1]. This antenna configuration combines the high gain capabilities ...
Microwave and Optical Technology Letters, 2014
A broadband reflectarray cell made of three parallel dipoles printed on a dielectric layer is pre... more A broadband reflectarray cell made of three parallel dipoles printed on a dielectric layer is presented. A 33% bandwidth is achieved for the cell made of dipoles, which is larger than that obtained for a reference cell consisting of three stacked square patches (26%). Using this cell, a 41-cm reflectarray antenna has been designed to produce a collimated beam at 9.5 GHz. The numerical results obtained for the reflectarray antenna made of parallel dipoles show a 1-dB bandwidth of 19%, a 65% efficiency, 0.2 dB of losses, and low levels of cross polarization (25 dB below the maximum). These results demonstrate a high performance for the proposed reflectarray antenna made of cells with three printed dipoles.
International Journal of Antennas and Propagation, 2012
Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both du... more Recent work on dual-reflector antennas involving reflectarrays is reviewed in this paper. Both dual-reflector antenna with a reflectarray subreflector and dual-reflectarrays antennas with flat or parabolic main reflectarray are considered. First, a general analysis technique for these two configurations is described. Second, results for beam scanning and contoured-beam applications in different frequency bands are shown and discussed. The performance and capabilities of these antennas are shown by describing some practical design cases for radar, satellite communications, and direct broadcast satellite (DBS) applications.
IEEE Transactions on Antennas and Propagation, 2008
A shaped-beam reflectarray based on patches, aperture-coupled to delay lines is demonstrated for ... more A shaped-beam reflectarray based on patches, aperture-coupled to delay lines is demonstrated for local multipoint distribution system (LMDS) central station antennas, in the 10.10-10.70 GHz band. The antenna must cover a 60°-sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the square patches, in order to achieve the phase distribution synthesized in the previous step. Two reflectarray antennas have been designed, one for vertical (V) and the other for horizontal (H) polarization. A breadboard for V-polarization has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.
IEEE Transactions on Antennas and Propagation, 2008
A significant improvement in the bandwidth of large reflectarrays is demonstrated using elements ... more A significant improvement in the bandwidth of large reflectarrays is demonstrated using elements which allow true-time delay. Two identical, large reflectarrays have been designed using different phase distributions to generate a collimated beam. In the former, the phase distribution is truncated to 360° as is usual in reflectarray antennas, while in the second, the true phase delay is maintained (three cycles of 360°). The chosen phase-shifter elements are based on previously measured and validated patches aperture-coupled to delay lines. The radiation patterns for both reflectarrays have been computed at several frequencies and the gain is represented as a function of frequency for both cases. Bandwidth curves are presented as a function of the reflectarray size.
Applied Physics Letters, 2013
A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-b... more A tunable graphene-based reflective cell operating at THz is proposed for use in reconfigurable-beam reflectarrays, or similarly to implement the so-called generalized law of reflection. The change in the complex conductivity of graphene when biased by an electric field allows controlling the phase of the reflected field at each element of the array. Additionally, the slow wave propagation supported by graphene drastically reduces the dimensions of the cell, which allows smaller inter-element spacing hence better array performance. An elementary cell is optimized and its scattering parameters computed, demonstrating a dynamic phase range of 300° and good loss figure for realistic chemical potential variations. Finally, a circuit model is proposed and shown to very accurately predict the element response.
In this work, the authors compare two designs of reflectarray antennas made of two different type... more In this work, the authors compare two designs of reflectarray antennas made of two different types of elements. One of the reflectarray designs is intended to generate a collimated beam and the other is intended to generate a contoured beam. In order to produce these radiation patterns, in one case three coplanar parallel dipoles are used as reflectarray elements, and in the other case stacked square patches are used as reflectarray elements. The results obtained indicate that the collimated beam and shaped beam reflectarrays made of parallel dipoles have a good bandwidth performance, which is comparable to that of the collimated beam and shaped beam reflectarrays made of stacked patches. However, the reflectarrays made of parallel dipoles achieve the broadband goal with a manufacturing process that is easier and cheaper than that required by the reflectarrays made of stacked patches.
A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station a... more A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station antenna for Local Multipoint Distribution System (LMDS) in the 10.10-10.70 GHz band. The antenna must cover a 60° sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the squared patches, in order to achieve the phase distribution synthesized in the previous step. A reflectarray antenna has been designed for vertical (V) polarization. A breadboard has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.
IEEE Antennas and Wireless Propagation Letters, 2019
A new reflectarray cell is proposed to simultaneously provide opposite phase shifts between ortho... more A new reflectarray cell is proposed to simultaneously provide opposite phase shifts between orthogonal circular polarizations at two frequencies (19.7 and 29.5 GHz) by applying a variable rotation technique independently at each frequency. The reflectarray cell, which consists of two dielectric layers with two levels of printed elements (dipoles and arcs), has been characterized for both circular and linear polarizations at each frequency. Apart from the implementation of the variable rotation technique at each frequency, the reflectarray cell provides an additional phase adjustment at the higher frequency, which can be used to shape the beam. This concept applied to multiple spot satellites in ÍTa-band will allow to produce two adjacent beams per feed in orthogonal circular polarizations at transmission and reception frequency bands.