kth.sePublications
Change search
Refine search result
12345 1 - 50 of 238
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Alex-Amor, Antonio
    et al.
    Univ Malaga, Dept Lenguajes & Ciencias Computac, Malaga 29071, Spain.;Univ Politecn Madrid, Informat Proc & Telecommun Ctr, Madrid 28040, Spain..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valerio, Guido
    Sorbonne Univ, Lab Genie Elect & Elect Paris, CNRS, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Ebrahimpouri, Mahsa
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Fernandez Gonzalez, Jose Manuel
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, Madrid 28040, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Glide-Symmetric Metallic Structures With Elliptical Holes for Lens Compression2020In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 68, no 10, p. 4236-4248Article in journal (Refereed)
    Abstract [en]

    In this article, we study the wave propagation in a metallic parallel-plate structure with glide-symmetric elliptical holes. To perform this study, we derived a mode-matching technique based on the generalized Floquet theorem for glide-symmetric structures. This mode-matching technique benefits from a lower computational cost since it takes advantage of the glide symmetry in the structure. It also provides physical insight into the specific properties of Floquet modes propagating in these specific structures. With our analysis, we demonstrate that glide-symmetric structures with periodic elliptical holes exhibit an anisotropic refractive index over a wide range of frequencies. The equivalent refractive index can be controlled by tuning the dimensions of the holes. Finally, by combining the anisotropy related to the elliptical holes and transformation optics, a Maxwell fish-eye (MFL) lens with a 33.33% size compression is designed. This lens operates in a wideband frequency range from 2.5 to 10 GHz.

  • 2.
    Alex-Amor, Antonio
    et al.
    Tech Univ Madrid, Informat Proc & Telecommun Ctr, Madrid 28040, Spain..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valerio, Guido
    Sorbonne Univ, UR2, Lab Elect & Electromagnetisme, F-75005 Paris, France..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Fernandez-Gonzalez, Jose M.
    Tech Univ Madrid, Informat Proc & Telecommun Ctr, Madrid 28040, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Elliptical Glide-Symmetric Holey Metasurfaces for Wideband Anisotropy2020In: 2020 14th European Conference on Antennas and Propagation (EUCAP 2020), Institute of Electrical and Electronics Engineers (IEEE) , 2020Conference paper (Refereed)
    Abstract [en]

    This paper presents a mode-matching technique to study the dispersive features of periodic structures composed of glide-symmetric elliptical holes. As a difference from purely numerical methods, our formulation provides physical insight on the Floquet harmonics. At the same time, the computational cost is reduced compared to general purpose commercial software. The fields inside the holes are described by means of Mathieu functions and subsequently used to compute the full 2-D dispersion diagrams. With the presented analysis, we demonstrate that glide-symmetric periodic structures with elliptical holes offer anisotropic refractive indexes over a wide range of frequencies.

  • 3.
    Alex-Amor, Antonio
    et al.
    Univ CEU San Pablo, Informat Technol Dept, Madrid 28668, Spain..
    Palomares-Caballero, Angel
    Telemat & Comunicac Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Escuela Tecn Super Ingn Informat, Seville 41012, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Padilla, Pablo
    Telemat & Comunicac Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Dispersion Analysis of Periodic Structures in Anisotropic Media: Application to Liquid Crystals2022In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 70, no 4, p. 2811-2821Article in journal (Refereed)
    Abstract [en]

    This article presents an efficient method to compute the dispersion diagram of periodic and uniform structures with generic anisotropic media. The method takes advantage of the ability of full-wave commercial simulators to deal with finite structures having anisotropic media. In particular, the proposed method extends the possibilities of commercial eigenmode solvers in the following ways: 1) anisotropic materials with nondiagonal permittivity and permeability tensors can be analyzed; 2) the attenuation constant can easily be computed in both propagating and stopband regions, and lossy materials can be included in the simulation; and 3) unbounded and radiating structures, such as leaky-wave antennas (LWAs), can be treated. The latter feature may be considered the most remarkable since the structures must be forcefully bounded with electric/magnetic walls in the eigensolvers of most commercial simulators. In this work, the proposed method is particularized for the study of liquid crystals (LCs) in microwave and antenna devices. Thus, the dispersion properties of a great variety of LC-based configurations are analyzed, from canonical structures, such as waveguide and microstrip, to complex reconfigurable phase shifters in ridge gap-waveguide technology and LWAs. Our results have been validated with previously reported works in the literature and with commercial software CST and HFSS.

  • 4.
    Alex-Amor, Antonio
    et al.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain.;Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Valerio, Guido
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Microwaves Grp, Dept Appl Phys 1, Escuela Tecn Super Ingn Informat, E-41012 Seville, Spain..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Fernandez-Gonzalez, Jose M.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Wave Propagation in Periodic Metallic Structures with Equilateral Triangular Holes2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 5, article id 1600Article in journal (Refereed)
    Abstract [en]

    This paper studies wave propagation in a periodic parallel-plate waveguide with equilateral triangular holes. A mode-matching method is implemented to analyze the dispersion diagram of the structure possessing glide and mirror symmetries. Both structures present an unexpected high degree of isotropy, despite the triangle not being symmetric with respect to rotations of 90 degrees. We give some physical insight on the matter by carrying out a modal decomposition of the total field on the hole and identifying the most significant modes. Additionally, we demonstrate that the electrical size of the triangular hole plays a fundamental role in the physical mechanism that causes that isotropic behavior. Finally, we characterize the influence of the different geometrical parameters that conform the unit cell (period, triangle size, hole depth, separation between metallic plates). The glide-symmetric configuration offers higher equivalent refractive indexes and widens the stopband compared to the mirror-symmetric configuration. We show that the stopband is wider as the triangle size is bigger, unlike holey structures composed of circular and elliptical holes where an optimal hole size exists.

  • 5. Algaba-Brazalez, A.
    et al.
    Vidarsson, F. V.
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Manholm, L.
    Johansson, M.
    Fonseca, N. J. G.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Compact Polarization Transformation in a Geodesic Luneburg Lens Antenna2021In: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2021, p. 1992-1993Conference paper (Refereed)
    Abstract [en]

    This paper describes the design of a compact polarizer that rotates the linear polarization of a fully metallic geodesic Luneburg lens antenna for applications requiring polarization diversity. The polarization rotation is achieved by loading the radiating aperture of the antenna with two metallic screens. The integrated antenna operates in the Ka-band, from 25 to 31 GHz, showing around 20% bandwidth with S11 below -10 dB, and a scanning range of 100°.

  • 6.
    Algaba-Brazalez, Astrid
    et al.
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Arnberg, Philip
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Vidarsson, Freysteinn Vidar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Manholm, Lars
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Crossover level improvement between beams in a geodesic lens antenna based on a generalized Luneburg lens2022In: 2022 16th European Conference on Antennas and Propagation (EuCAP), Institute of Electrical and Electronics Engineers (IEEE), 2022Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a geodesic generalized Luneburg lens operating in the 60-GHz band, from 57 to 67 GHz, designed with the goal to improve the crossover level between beams with respect to previously reported fully metallic Luneburg lenses, while providing highly directive beams and wide scanning coverage. We have combined the use of a generalized Luneburg lens and the design of a compact feeding type based on ridge waveguide in order to achieve an optimum crossover level between beams keeping in mind manufacturing simplicity. The numerical evaluation of the final integrated lens design including 21 ridge waveguide feeding ports shows a vertical bar S-11 vertical bar parameter below -13.6 dB over the frequency band of interest, a scanning range of +/- 52 degrees, a realized gain higher than 19 dBi over the whole operating bandwidth, and a crossover level value between -3.5 dB and -4.2 dB from the lowest to the highest frequency of operation.

  • 7.
    Algaba-Brazalez, Astrid
    et al.
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Manholm, Lars
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Overview of research on metalenses and geodesic lenses for 5G/6G applications in Ericsson2022In: 2022 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), Institute of Electrical and Electronics Engineers (IEEE) , 2022, p. 103-104Conference paper (Refereed)
    Abstract [en]

    In this contribution, we outline the challenges and opportunities of designing parallel-plate lenses implemented with metasurfaces (i.e. metalenses) or with geodesic surfaces (i.e. geodesic lenses), for next generation communication systems (5G and beyond). The requirements that we studied in our investigations are low scanning loss, high efficiency, high crossover level, polarization diversity, wide scanning range, low antenna profile, manufacturing simplicity, and cost-effectiveness. These requirements are key when designing and developing antennas for 5G and beyond.

  • 8.
    Algaba-Brazalez, Astrid
    et al.
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Wang, Hairu
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Castillo Tapia, Pilar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Manholm, Lars
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Flexible 6G antenna systems based on innovative lenses combined with array antennas2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, Institute of Electrical and Electronics Engineers (IEEE), 2023Conference paper (Refereed)
    Abstract [en]

    In this article, we propose an innovative concept to realize flexible and cost-effective array antenna systems for next generation communication systems. The idea is to tailor the performance of an antenna array to different use case scenarios by applying a customized dielectric lens placed in front of the array. By combining a lens with an array, we can improve certain performance properties of the antenna system and adapt it for unique site locations and requirements. Moreover, the lens may also act as a radome, providing mechanical protection from environmental conditions. This study consists of exploring the possibilities of using a lens to increase the gain of the antenna in certain directions: scanning range close to broadside (from 0 degrees to 30 degrees), and extreme scanning ranges (from 60 degrees to 80 degrees).

  • 9.
    Amendola, Giandomenico
    et al.
    Univ Calabria, Dipartimento Ingn Informat Modellist Elettron & Si, I-87036 Arcavacata Di Rende, CS, Italy..
    Cavallo, Daniele
    Delft Univ Technol, Fac Elect Engn Math & Comp Sci, Dept Microelect, NL-2628 CD Delft, Netherlands..
    Chaloun, Tobias
    Ulm Univ, Inst Microwave Engn, D-89081 Ulm, Germany..
    Defrance, Nicolas
    Univ Lille, Univ Polytech Hauts de France, IEMN Inst Elect Microelect & Nanotechnol, CNRS,Cent Lille, F-59000 Lille, France..
    Goussetis, George
    Heriot Watt Univ, Inst Sensors Signals & Syst, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Scotland..
    Margalef-Rovira, Marc
    Univ Lille, Univ Polytech Hauts de France, IEMN Inst Elect Microelect & Nanotechnol, CNRS,Cent Lille, F-59000 Lille, France..
    Martini, Enrica
    Univ Siena, Dept Informat Engn & Math, I-53100 Siena, Italy..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valenta, Vaclav
    European Space Agcy, European Space Res & Technol Ctr, NL-2201 AZ Noordwijk, Netherlands..
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Submillimeter Waves Sect, NL-2200 AG Noordwijk, Netherlands..
    Ettorre, Mauro
    Univ Rennes, CNRS, IETR, F-35000 Rennes, France..
    Low-Earth Orbit User Segment in the Ku and Ka-Band2023In: IEEE Microwave Magazine, ISSN 1527-3342, E-ISSN 1557-9581, Vol. 24, no 2, p. 32-48Article in journal (Refereed)
    Abstract [en]

    Low-Earth orbit (LEO) constellations are revolutionizing the world of satellite communication (Satcom), providing new opportunities to manufacturers and operators and enabling innovative and attractive services to users.

  • 10.
    Ansari, Maral
    et al.
    Univ Technol Sydney, Global Big Data Technol Ctr, Sydney, NSW, Australia..
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Sub Millimetre Waves Sect, Noordwijk, Netherlands..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Guo, Y. Jay
    Univ Technol Sydney, Global Big Data Technol Ctr, Sydney, NSW, Australia..
    A Lightweight Metalized-Insert Luneburg Lens2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, Institute of Electrical and Electronics Engineers (IEEE), 2023Conference paper (Refereed)
    Abstract [en]

    In this paper, a lightweight spherical Luneburg lens with high performance is introduced for use in the frequency range 1 (FR1). The continuously varying refractive index profile of the lens is implemented using a quasi-isotropic partially metalized periodic structure. Much of the lens volume is made of foam, so the design is lightweight, making it applicable for low-band microwave frequency communication systems and, more specifically, 5G communications in FR1. The periodic structure allows a simple and low-cost layered construction with a quasi-isotropic response. This approach improves the scanning performance of the lens in all angular directions when compared to equivalent lens designs previously reported. Such a structure is an ideal candidate for high-gain multi-beam communication systems.

  • 11.
    Arnberg, Philip
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Petersson, Oscar Barreira
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    High Refractive Index Electromagnetic Devices in Printed Technology Based on Glide-Symmetric Periodic Structures2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 9, article id 3216Article in journal (Refereed)
    Abstract [en]

    We demonstrate the beneficial effects of introducing glide symmetry in a two-dimensional periodic structure. Specifically, we investigate dielectric parallel plate waveguides periodically loaded with Jerusalem cross slots in three configurations: conventional, mirror- and glide-symmetric. Out of these three configurations, it is demonstrated that the glide-symmetric structure is the least dispersive and has the most isotropic response. Furthermore, the glide-symmetric structure provides the highest effective refractive index, which enables the realization of a broader range of electromagnetic devices. To illustrate the potential of this glide-symmetric unit cell, a Maxwell fish-eye lens is designed to operate at 5 GHz. The lens is manufactured in printed circuit board technology. Simulations and measurements are in good agreement and a measured peak transmission coefficient of -0.5 dB is achieved.

  • 12.
    Bagheriasl, Mohammad
    et al.
    Sorbonne Univ, L2E, UR2, F-75005 Paris, France..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valerio, Guido
    Sorbonne Univ, L2E, UR2, F-75005 Paris, France..
    Bloch Analysis of Artificial Lines and Surfaces Exhibiting Glide Symmetry2019In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 67, no 7, p. 2618-2628Article in journal (Refereed)
    Abstract [en]

    Glide-symmetric structures have recently emerged as a smart choice to design planar lenses and electromagnetic bandgap materials. We discuss here the conditions under which a glide-symmetric structure is equivalent to a nonglide-symmetric structure with a reduced period. To this aim, we propose an analysis method based on network theory to efficiently derive the dispersive behavior of these periodic structures. Both phase and attenuation constants can be determined, with potential applications to both guiding and radiating structures. Retaining higher order modal interactions among cells helps to derive the dispersive behavior of periodic structures more accurately. Furthermore, we take advantage of the higher symmetry of these structures to decrease the computational cost by considering only one half or one-quarter of a unit cell instead of the entire cell. We study one and 2-D glide-symmetric structures and confirm the validity of our analysis with comparisons from commercial software.

  • 13.
    Björkqvist, Oskar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Additive Manufactured Three Dimensional Luneburg Lens for Satellite Communications2019In: 13th European Conference on Antennas and Propagation, EuCAP 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8739803Conference paper (Refereed)
    Abstract [en]

    A method for designing gradient refractive index (GRIN) lenses with additive manufacturing or 3D-printing at K-u band is presented. To demonstrate the potential of the method, we designed a Luneburg lens using a single low-loss dielectric material available for 3D-printers. The gradient index is realized by varying the local material fill density of the lens. We demonstrate with full wave simulations that the structure is able to transform a spherical electromagnetic wave to a plane wave. When the lens is fed with a rectangular waveguide, the overall antenna has a gain of 23 dBi with side lobe levels of -12.5 dB in K-u band. This lens, when integrated with a circular polarized feeding system, could find application for ground satellite communications.

  • 14.
    Björkqvist, Oskar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Silver, Gustaf
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Kolitsidas, Christos
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Jonsson, B. Lars G.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Wireless Sensor Network Utilizing Radio-Frequency Energy Harvesting for Smart Building Applications2018In: IEEE Antennas & Propagation Magazine, ISSN 1045-9243, E-ISSN 1558-4143, Vol. 60, no 5, p. 124-136Article in journal (Refereed)
    Abstract [en]

    The scope of this article is to develop a modular radio-frequency (RF) energy-harvesting system for smart buildings that can act as a power source for sensing devices. Electromagnetic field-strength measurements at the main campus of the KTH Royal Institute of Technology in Stockholm, Sweden, were carried out to define the strength of the available ambient signals. Mainly two spectra were available for possible RF harvesting, i.e., two cellular bands [GSM1800 and third generation (3G)] and the 2.45-GHz Wi-Fi band. Based on these measurements, a modular approach for the system was adopted. The system is composed from two modules: 1) a Wi-Fi rectenna system composed of eight dual-polarized patch antennas and 16 rectifiers to produce eight differential voltage sources connected in series and 2) a cellular rectenna system composed of eight linear tapered slot antennas and eight rectifiers to produce four differential voltage sources connected in series. We propose an innovative multiple-input, single-output (MISO) wave rectifier that yields an efficient differential output. Both rectenna modules offer full azimuthal coverage and can operate either together or independently.

  • 15.
    Björkqvist, Oskar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Additive manufactured dielectric Gutman lens2019In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 55, no 25, p. 1318-1320Article in journal (Refereed)
    Abstract [en]

    In this Letter, the design of a 3D printed fully dielectric Gutman lens is presented. The authors demonstrate the feasibility of using highly accessible and cheap additive manufacturing technology to produce a compact and high performing antenna lens. The lens is designed to operate at Ku band and utilises a flat feed surface that approximates the focal sphere. The flat feed surface allows for beam steering that requires only translational movement of the feed. The lens has a measured realised gain of 20 dBi with 3 dB scan loss at +45°. The lens finds applications in systems that require high gain antennas, such as the new generation of satellite and 5G communications and radar technology.

  • 16.
    Brazalez, Astrid Algaba
    et al.
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Manhohni, Lars
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Mattsson, Martin
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Implementation of a compact Ka-band parallel plate Luneburg lens based on a hybrid dielectric/metasurface unit cell2019In: 13th European Conference on Antennas and Propagation, EuCAP 2019, IEEE, 2019, article id 8740306Conference paper (Refereed)
    Abstract [en]

    The complete implementation and numerical validation of a compact cost-effective multiport parallel plate Luneburg lens antenna operating at 28 GHz is described in this paper. The lens design consists of two parallel plates separated by a gap where each of them contains a metasurface structure based on a new type of combined dielectric/holey unit cell periodically arranged in a glide-symmetric configuration. The required refractive index is achieved by a combination of coarse control by adding a dielectric in the gap, and fine tuning by changing the height of the holes. The simulations of the final prototype including a flare to ensure a smooth wave transition from the parallel plate configuration to air, as well as a coaxial-to-waveguide-to-parallel plate feeding, show a 20% bandwidth for 11.5 dB return loss, and the crosstalk remains below -15 dB for the same frequency band.

  • 17.
    Brazalez, Astrid Algaba
    et al.
    Ericsson AB, Ericsson Res, Gothenburg, Sweden. attsson, Martin; Quevedo-Teruel, Oscar.
    Manholm, Lars
    Johansson, Martin
    Mattsson, Martin
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    A Ka-band glide-symmetric planar Luneburg lens with combined electric/metasurface for 5G communications2018In: 2018 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    Here, we propose a cost-effective metasurface lens solution based on the use of metallic glide-symmetric unit cell combined with a dielectric sheet. Our solution reduces significantly the manufacturing and assembly complexity of previously investigated Ka-band Luneburg lens implemented in glide symmetry technology. The required refractive index for this unit cell has been studied for the geometrical parameters, and an efficient transition between different media in the parallel plate configuration of the lens is also investigated.

  • 18. Camacho, Miguel
    et al.
    Mitchell-Thomas, Rhiannon C.
    Hibbins, Alastair P.
    Sambles, J. Roy
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Designer surface plasmon dispersion on a one-dimensional periodic slot metasurface with glide symmetry2017In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 42, no 17, p. 3375-3378Article in journal (Refereed)
    Abstract [en]

    In this Letter, we explore the dispersion of spoof surface plasmons supported by a single-layer glide-symmetric structure. This structure consists of an infinitely long double-notched slot perforated in a metal layer. The presence of a degeneracy of the two lowest-order modes at the Brillouin zone boundary, which have non-zero group velocity is explained and experimentally demonstrated. Further, the dependence of the band structure when glide-symmetric configuration is broken is also explored.

  • 19. Camacho, Miguel
    et al.
    Mitchell-Thomas, Rhiannon C.
    Hibbins, Alastair P.
    Sambles, J. Roy
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Mimicking glide symmetry dispersion with coupled slot metasurfaces2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, no 12, article id 121603Article in journal (Refereed)
    Abstract [en]

    In this letter, we demonstrate that the dispersion properties associated with glide symmetry can be achieved in systems that only possess reflection symmetry by balancing the influence of two sublattices. We apply this approach to a pair of coupled slots cut into an infinite perfectly conducting plane. Each slot is notched on either edge, with the complete two-slot system having only mirror symmetry. By modifying the relative size of the notches on either side of the slots, we show that a linear dispersion relation with a degeneracy with non-zero group velocity at the Brillouin zone boundary can be achieved. These properties, until now, only found in systems with glide symmetry are numerically and experimentally validated. We also show that these results can be used for the design of ultra-wideband one-dimensional leaky wave antennas in coplanar waveguide technology.

  • 20.
    Casaletti, Massimiliano
    et al.
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Valerio, Guido
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Burghignoli, Paolo
    Sapienza Univ Rome, Dept Informat Engn Elect & Telecommun, Via Eudossiana 18, I-00184 Rome, Italy..
    An overview of metasurfaces for thin antenna applications2020In: Comptes rendus. Physique, ISSN 1631-0705, E-ISSN 1878-1535, Vol. 21, no 7-8, p. 659-676Article in journal (Refereed)
    Abstract [en]

    In recent years, metasurfaces have become a rapidly growing domain of research in several fields of engineering and applied physics due to their ability to manipulate both phase and amplitude of electromagnetic fields. These artificial 2D-materials, usually composed of metallic elements printed on dielectric substrates, have the advantages of being low profile, lightweight as well as easy to fabricate and integrate with standard circuit technologies. In this context, this paper reviews the latest progress in metasurface antenna design, where metasurfaces are used to miniaturize the profile, increase the bandwidth, and control the radiation pattern in the near- and far-field regions.

  • 21.
    Castañer, Manuel Sierra
    et al.
    Universidad Politécnica de Madrid, Madrid, Spain.
    Monni, Stefania
    TNO Netherlands, The Hague, The Netherlands.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Guest editorial: EuCAP2021 special section2022In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 16, no 6, p. 303-304Article in journal (Refereed)
  • 22.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Liao, Qingbi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Sub Millimetre Waves Sect, Noordwijk, Netherlands..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Modulated Geodesic Lens Antenna Array2021In: 2021 15Th European Conference On Antennas And Propagation (Eucap), IEEE , 2021Conference paper (Refereed)
    Abstract [en]

    We present the design of a geodesic Luneburg lens array antenna. The water drop lens is a compact and highly-efficient alternative to the planar Luneburg lens. Our proposed lens antenna is able to steer 110 deg in azimuth with negligible scan losses. On the other hand, the linear array of four elements increases 6 dB of directivity in elevation. A feeding network composed by a 1:4 power splitter and four different phase shifters allows to steer 60 deg in elevation.

  • 23.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Dept Fis Aplicada 1, Seville, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Multimodal Transfer Matrix Approach for the Analysis and Fundamental Understanding of Periodic Structures with Higher Symmetries2022In: 2022 16TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP), Institute of Electrical and Electronics Engineers (IEEE) , 2022Conference paper (Refereed)
    Abstract [en]

    The Multimodal Transfer Matrix Method (MMTMM) is a hybrid approach that efficiently computes the dispersion relation of a periodic structure. It is able to retrieve both the phase shift and attenuation constant of any arbitrary structure susceptible to be analyzed by means of commercial simulators. Here, we propose the use of this method in order to get a physical insight of periodic structures possessing higher symmetries. The MMTMM is here explained and corroborated with two different structures: a glide-symmetric dielectric-filled corrugated rectangular waveguide and a three-fold twist-symmetric bricks embedded in a dielectric waveguide. The first structure allows for the propagation of backward modes below the hollow waveguide cut-off frequency, whereas the second one has handedness selection.

  • 24.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, ETS Ingn Informat, Dept Appl Phys 1, Seville 41012, Spain..
    Yakovlev, Alexander
    Univ Mississippi, Dept Elect & Comp Engn, Oxford, MS 38677 USA..
    Valerio, Guido
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Lab Genie Elect & Elect Paris, CentraleSupelec, CNRS, F-91192 Paris, France..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Study of Forward and Backward Modes in Double-Sided Dielectric-Filled Corrugated Waveguides2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 18, article id 6293Article in journal (Refereed)
    Abstract [en]

    This work studies the propagation characteristics of a rectangular waveguide with aligned/misaligned double-sided dielectric-filled metallic corrugations. Two modes are found to propagate in the proposed double-sided configuration below the hollow-waveguide cutoff frequency: a quasi-resonant mode and a backward mode. This is in contrast to the single-sided configuration, which only allows for backward propagation. Moreover, the double-sided configuration can be of interest for waveguide miniaturization on account of the broader band of its backward mode. The width of the stopband between the quasi-resonant and backward modes can be controlled by the misalignment of the top and bottom corrugations, being null for the glide-symmetric case. The previous study is complemented with numerical results showing the impact of the height of the corrugations, as well as the filling dielectric permittivity, on the bandwidth and location of the appearing negative-effective-permeability band. The multi-modal transmission-matrix method has also been employed to estimate the rejection level and material losses in the structure and to determine which port modes are associated with the quasi-resonant and backward modes. Finally, it is shown that glide symmetry can advantageously be used to reduce the dispersion and broadens the operating band of the modes.

  • 25.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Rico-Fernandez, J.
    Northern Waves AB, Stockholm, Sweden.
    Mesa, F.
    Department of Applied Physics 1, ETS Ingeniería Informática, Universidad de Sevilla, Seville, Spain.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Ray-Tracing Model for the Design and Efficiency Calculation of a Monolithic Geodesic Lens Array Antenna2024In: 18th European Conference on Antennas and Propagation, EuCAP 2024, Institute of Electrical and Electronics Engineers (IEEE) , 2024Conference paper (Refereed)
    Abstract [en]

    We propose the use of a generalized ray-tracing model to design geodesic lens array antennas. This model is capable of computing the radiation patterns and taking into account losses due to finite conductivity and surface roughness, which are essential when producing prototypes as single monolithic pieces. The ray-tracing model is used to design a modified Rinehart-Luneburg lens that shows very good agreement with simulations while significantly decreasing computation time. The profile of the lens is designed in such a way that it can be vertically stacked in an array and produced as a single piece. The lens array antenna is manufactured as a single monolithic piece using the laser powder-bed fusion technique. The tests of this prototype validate the use of additive manufacturing for geodesic lens antennas operating in V-band.

  • 26.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Rico-Fernandez, Jose
    Northern Waves AB, S-11428 Stockholm, Sweden..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    V-Band Monolithic Additive-Manufactured Geodesic Lens Array Antenna2023In: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 22, no 10, p. 2527-2531Article in journal (Refereed)
    Abstract [en]

    Fully metallic geodesic lens antennas are popular for millimeter-wave band applications due to their simplicity, robustness, and low loss. Here, we report the experimental results of a geodesic lens array antenna, which was specifically designed to be additive-manufactured in one single piece using laser powder-bed fusion (LPBF). LPBF in aluminum alloy AlSi10Mg is able to produce high conductivity and relatively low surface roughness, so the antenna is highly directive and efficient. In addition, LPBF increases the robustness of the design since the lens array is monolithic, i.e., the risks associated with the assembly, including misalignments and undesired air gaps between pieces, are totally eliminated.

  • 27.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Van Gassen, Kwinten
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Chen, Qiao
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Sipus, Zvonimir
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dispersion Analysis of Twist-Symmetric Dielectric Waveguides2021In: Photonics, E-ISSN 2304-6732, Vol. 8, no 6, p. 206-206Article in journal (Refereed)
    Abstract [en]

     We propose a circular twist-symmetric dielectric waveguide that is polarization-selective.In the practical implementation of optical fibers, a selective circular polarization is more convenientthan its linearly polarized counterpart where previous knowledge of the emitted polarization fromthe transmitter is unknown. The analysis of the waveguide was conducted with three methods: aneigenmode approach, simulation of a truncated structure, and the so-called multimodal transfermatrix method (MMTMM). The presented simulations demonstrate that the operational band canbe manipulated by tuning the parameters of the structure. Furthermore, the MMTMM allows for adirect and accurate calculation of the attenuation constant of the rejected circular polarization.

    Download full text (pdf)
    fulltext
  • 28.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Van Gassen, Kwinten
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Seville, Spain..
    Sipus, Zvonimir
    Univ Zagreb, Fac Elect Engn & Comp, Zagreb, Croatia..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Characterization of twist-symmetric dielectric waveguides2021In: 2021 15th European conference on antennas and propagation (EUCAP), Institute of Electrical and Electronics Engineers (IEEE) , 2021Conference paper (Refereed)
    Abstract [en]

    Here, we study the propagation of a twist-symmetric dielectric rod with three different methods: eigenmode solver, multimode Bloch analysis, and scattering parameters of a truncated structure. With the eigenmode analysis, we demonstrate that these structures permit the propagation of circularly polarized modes, and only one of the modes has a stopband in the first Brillouin zone. These results are corroborated with the simulation of a truncated structure, demonstrating that the propagation is only possible for one of the modes at a given frequency band. Finally, the multimode Bloch analysis is used to also characterize the attenuation constant in the stopband.

  • 29.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Yang, Shiyi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Seville, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Radiation efficiency estimation of lossy geodesic lens antennas based on a ray-tracing technique2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, Institute of Electrical and Electronics Engineers (IEEE), 2023Conference paper (Refereed)
    Abstract [en]

    Here, we propose a generalized ray-tracing (RT) model to accurately compute the radiation patterns and radiation efficiency of lossy non-rotationally symmetric geodesic lens antennas. The RT model uses geometrical optics to obtain the ray paths from the source to the aperture, ray tube theory to calculate the field amplitude distribution, and Kirchhoff's diffraction formula to compute the radiation pattern. Losses in geodesic lenses are mainly produced by the finite conductivity and roughness of the metallic plates. These losses are added to the calculation of the radiation pattern to estimate the radiation efficiency of the antenna. To demonstrate the accuracy of the proposed RT model, a geodesic half-Maxwell fish-eye lens is designed. Radiation patterns, scan losses, and radiation efficiency are calculated. These results agree well with those computed by full-wave simulations.

  • 30.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Algaba-Brazalez, Astrid
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Manholm, Lars
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, Gothenburg, Sweden..
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & SubMillimetre Waves Sect, Noordwijk, Netherlands..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Azimuth and Elevation Scanning with Stacked Modulated Geodesic Luneburg Lenses2022In: 2022 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), Institute of Electrical and Electronics Engineers (IEEE) , 2022, p. 5-6Conference paper (Refereed)
    Abstract [en]

    Here, we propose a modulated geodesic lens antenna array in E-band (56-62 GHz), which has scanning abilities in both azimuth and elevation. The array consists of four lens antenna elements, and each lens antenna produces 13 independent beams that cover 110 degrees in the H-plane with scan losses below 1 dB. The array is fed with a 1:4 power divider comprising three phase shifters to scan in the E-plane. The distance between lenses in the E-plane is 0.7 wavelengths at 60 GHz. The E-plane coverage is 60 degrees with scan losses around -2.2 dB. The maximum realized gain varies from 20.8 to 24.1 dB across the frequency band.

  • 31.
    Castillo Tapia, Pilar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Algaba-Brazalez, Astrid
    Ericsson AB, Ericsson Res, S-41756 Gothenburg, Sweden..
    Manholm, Lars
    Ericsson AB, Ericsson Res, S-41756 Gothenburg, Sweden..
    Johansson, Martin
    Ericsson AB, Ericsson Res, S-41756 Gothenburg, Sweden..
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Submillimetre Waves Sect, NL-2200 AG Noordwijk, Netherlands..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Two-Dimensional Beam Steering Using a Stacked Modulated Geodesic Luneburg Lens Array Antenna for 5G and Beyond2023In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 71, no 1, p. 487-496Article in journal (Refereed)
    Abstract [en]

    Antennas for future communication systems are required to be highly directive and steerable to compensate for the high path loss in the millimeter-wave band. In this work, we propose a linear array of modulated geodesic Luneburg lens (the so-called water drop lens) antennas operating at 56-62 GHz. The lens array antenna features 2-D beam scanning with low structural complexity. The lenses are fully metallic and implemented in parallel plate waveguides (PPWs), meaning that they are highly efficient. Each lens is fed with 13 rectangular waveguides surrounded by glide-symmetric holes to suppress leakage. The lenses provide 110? beam coverage in the H-plane with scan losses below 1 dB. In order to scan in the E-plane, we use a feeding network based on a 1:4 power divider and three phase shifters. In this configuration, the array can scan 60? in the E-plane, albeit with higher scanning losses than in the H-plane. The lens array is manufactured and a good agreement between simulated and experimental results is obtained.

  • 32.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Habiboglu, Özüm
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Mesa, Francisco
    Univ Seville, ETS Ingn Informat, Dept Appl Phys 1, Seville 41012, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Ray-Tracing and Physical-Optics Model for Planar Mikaelian Lens Antennas2024In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 72, no 2, p. 1735-1744Article in journal (Refereed)
    Abstract [en]

    This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides (PPWs). With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristics, the planar Mikaelian lens antennas are easy to fabricate and integrate into standard planar feeds. A numerical computation of the ray paths based on Snell's law describes the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far-field of the lens antenna. The information on far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and a significant reduction in computation resources and times.

  • 33.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Seville, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    Broadbeam Geodesic H-plane Horn Antenna2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    We propose broadbeam geodesic H-plane horn antennas, potentially useful as simple primary feeds for reflectors. Since H-plane horn antennas are implemented in a structure similar to the parallel-plate waveguide, we show that a numerically efficient ray-tracing model can be used to describe wave propagation through them. Using the efficient ray-tracing tool, we optimize three different height profiles to obtain broad beams with different half-power beamwidths at the central operating frequency of 30 GHz. All implemented structures have beamwidths larger than those of a planar reference counterpart.

  • 34.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Mesa, Francisco
    Department of Applied Physics 1, Universidad de Sevilla, Seville, Spain.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Combined Ray-Tracing and Physical-Optics Model for Flat-Aperture PPW Lens Antennas2024In: 18th European Conference on Antennas and Propagation, EuCAP 2024, Institute of Electrical and Electronics Engineers (IEEE) , 2024Conference paper (Refereed)
    Abstract [en]

    This paper proposes a combined ray-tracing and physical-optics model to analyze parallel-plate-waveguide lens antennas with a flat aperture. A family of rays is traced from the source to a set of target points on the lens radiating aperture, giving a description of the aperture electric field. On the basis of the physical-optics approximation, an equivalent magnetic current is then assumed and used to evaluate the far-field radiation characteristics in every direction. This numerical approach is validated by applying it to a particular planar Mikaelian lens antenna and comparing the results with those obtained using a commercial full-wave simulator.

  • 35.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Seville, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Cost-effective fully-metallic geodesic H-plane horn antenna2022In: 2022 International Symposium On Antennas And Propagation (ISAP), Institute of Electrical and Electronics Engineers (IEEE) , 2022, p. 173-174Conference paper (Refereed)
    Abstract [en]

    Geodesic lenses are proposed as a compelling solution for beamforming at high frequencies due to their advantageous properties of low cost and high efficiency. Actually, the concept of geodesics is a very useful framework with many applications in different fields. Here, we propose a geodesic H-plane horn antenna. The height profile of the horn antenna is modulated to alleviate the phase error and realize a directive beam. The simulation results show an enhancement of over 2.5 dB in realized gain of the geodesic horn antenna compared to a planar reference counterpart.

  • 36.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Mesa, Francisco
    Department of Applied Physics 1, Universidad de Sevilla, Seville, Spain.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Experimental Validation of Ray-Tracing and Physical-Optics Model for Geodesic H-plane Horn Antennas2024In: 18th European Conference on Antennas and Propagation, EuCAP 2024, Institute of Electrical and Electronics Engineers (IEEE) , 2024Conference paper (Refereed)
    Abstract [en]

    In this contribution, we provide an experimental validation of a ray-tracing and physical-optics model for geodesic horn antennas. The proposed model employs a ray-tracing technique to obtain electric fields in the horn aperture and applies the field equivalence principle in physical optics to evaluate the three-dimensional radiation characteristics of the geodesic horn antennas. The numerical results agree well with the measurements in terms of radiation patterns in the uv-plane, the principal E- and H-plane patterns, and directivities.

  • 37.
    Chen, Ming Zheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, ETS Ingn Informat, Seville 41012, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Geodesic H-Plane Horn Antennas2023In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 71, no 8, p. 6329-6339Article in journal (Refereed)
    Abstract [en]

    This article describes a detailed procedure that allows for a time-efficient design of fully metallic geodesic H-plane horn antennas using an in-house ray-tracing method together with an optimization algorithm. With all the propagation in the air, geodesic H-plane horn antennas are of low loss and highly efficient. The proposed geodesic H-plane horn antennas provide a new degree of freedom, the height profile, to alleviate phase errors, realizing high gains and aperture efficiencies. Optimizations are implemented to design the height profile for a given target, enabled by the highly accurate and time-efficient in-house ray-tracing model. To demonstrate the correctness and versatility of the proposed design procedure, two prototypes are manufactured with computerized numerical control (CNC) machining and compared to their planar counterparts, with the aim of a high increased gain and aperture efficiency, respectively. The prototypes maintain good frequency stability from 26 to 33GHz, with sidelobe levels lower than -15dB and return loss better than 15dB. The first prototype improves the realized gain by over 5dB compared to the reference horn, while the second prototype achieves an aperture efficiency of around 65% within the operating frequency band.

  • 38.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Fu, Wenfu
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Zhao, Kun
    Aalborg Univ, Dept Elect Syst, Antennas Propagat & Millimetre Wave Syst APMS Sec, DK-9100 Aalborg, Denmark..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Dual-polarized Geodesic Lens Antenna at sub-THz2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, IEEE , 2023Conference paper (Refereed)
    Abstract [en]

    We present a dual-polarized lens antenna for point-to-multipoint communications at sub-THz. The lens is constructed by a doubly-curved parallel plate following a geodesic lens shape equivalent to the Luneburg index profile. The polarization is changed by metallic screens patterned with complementary split resonant rings (CSRRs). These screens are integrated in the radiation aperture of the lens. Two lenses are stacked up, one for each polarization. Each lens is fed by 11 waveguide ports, providing beam steering or multiple beams. The antenna is fully metallic and hence, highly efficient. In the operating band from 115 GHz to 125 GHz, the simulation shows a realized gain of 20 dBi with a maximum scan loss of 0.6 dB up to 60 degrees, a cross-polarization discrimination around 20 dB, and an insertion loss smaller than 1.5 dB.

  • 39.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Southeast Univ, State Key Lab Millimeter Wave, Nanjing 210096, Jiangsu, Peoples R China..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dispersion Analysis of Coaxial Line Loaded with Twist-Symmetric Half-Rings2018In: 2018 IEEE International Workshop on Antenna Technology, iWAT2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    A coaxial line with half-rings connected to its external conductor is proposed in this paper, to investigate the dispersion properties of a twist-symmetric electromagnetic configuration. We demonstrate that the propagating modes in a twist-symmetric structure are more linear than a conventional structure. Additionally, the bandgap at the Brillouin zone boundaries can be manipulated by tuning the relative angular orientation or translation of the rings. This tuning is equivalent to changing the order of the twist symmetry from 4- to 2-fold. Our proposed geometry finds potential application in fully-metallic reconfigurable filters and phase shifters.

  • 40.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Jiangsu, Peoples R China.
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valerio, Guido
    Sorbonne Univ, Lab Elect & Electromagnetisme, F-75005 Paris, France..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Modeling and Dispersion Analysis of Coaxial Lines With Higher Symmetries2018In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 66, no 10, p. 4338-4345Article in journal (Refereed)
    Abstract [en]

    In this paper, 1-D periodic structures possessing higher symmetries are proposed and investigated in terms of their dispersion properties. The proposed structures are coaxial lines with coaxial rings periodically loaded on their inner or outer conductors. The higher symmetries, namely, glide and twist symmetries, are obtained by performing an additional geometrical operation within the unit cell of the periodic structure. We demonstrate that the propagating modes exhibit a lower frequency dispersion in higher symmetric coaxial lines. Moreover, the conventional stopbands of periodic structures at their Brillouin zone boundaries can be controlled by breaking the higher symmetry or changing the order of the twist symmetry. A circuit-based analytical method is proposed to calculate the dispersion diagram of the glide-symmetric coaxial lines. The results are validated with a full-wave simulation. Moreover, several prototypes of the twist-symmetric coaxial lines are manufactured and measured. A remarkable agreement is achieved between the measurements and simulations, validating the theoretical results. The proposed structures find potential applications in leaky-wave antennas and fully metallic reconfigurable filters and phase shifters.

  • 41.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. KTH Royal Inst Technol, Div Electromagnet Engn, SE-10044 Stockholm, Sweden..
    Giusti, Federico
    KTH. KTH Royal Inst Technol, Div Electromagnet Engn, SE-10044 Stockholm, Sweden..
    Valerio, Guido
    Sorbonne Univ, Lab G enie Elect & Elect Paris, CNRS, F-75252 Paris, France.;Univ Paris Saclay, Lab G enie Elect & Elect Paris, Cen Sup elec, CNRS, F-91192 Gif Sur Yvette, France..
    Mesa, Francisco
    Univ Seville, ETS Ingn Inform at, Dept Appl Phys 1, Seville 41012, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. KTH Royal Inst Technol, Div Electromagnet Engn, SE-10044 Stockholm, Sweden..
    Anisotropic glide-symmetric substrate-integrated-holey metasurface for a compressed ultrawideband Luneburg lens2021In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 118, no 8, article id 084102Article in journal (Refereed)
    Abstract [en]

    An anisotropic unit cell based on glide symmetry is proposed for tailoring a metasurface that engineers an optically transformed Luneburg lens. Thanks to the optical transformation, the size of the lens is reduced by 25%. The proposed lens is ultrawideband, and it covers multi-octave frequency bands. The required constitutive materials are achieved in an air gap bounded by top and bottom glide-symmetric metasurfaces; i.e., they are off-shifted by half the period. Each surface is implemented in standard printed-circuit-board technology, and its unit cell consists of a grounded substrate with an elliptical holey top cladding surrounded by metalized through-vias. This technology, known as substrate-integrated-holes (SIHs), mimics the operation of holes drilled in a parallel plate but provides the higher effective refractive index required for lens compression. The SIH is attractive for practical applications since most of the energy propagates in the air gap between the two surfaces and, therefore, it features low dielectric losses. Thanks to glide symmetry, the proposed metasurface demonstrates a further enhanced effective refractive index with lower dispersion over an ultra-wide bandwidth in comparison to its non-glide counterpart. A multimodal transfer-matrix approach is here employed to carry out the Bloch analysis of the proposed SIH. Published under license by AIP Publishing.

  • 42.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    Horsley, Simon A. R.
    Univ Exeter, Dept Phys & Astron, Stocker Rd, Exeter EX4 4QL, Devon, England..
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Submillimeter Waves Sect, NL-2200 AG Noordwijk, Netherlands..
    Tyc, Tomas
    Masaryk Univ, Inst Theoret Phys & Astrophys, Fac Sci, Kotlarska 2, Brno 61137, Czech Republic..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering and Fusion Science.
    A General Solution for Double-Layer Gradient-Index and Geodesic Lenses with Rotational Symmetry2023In: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP, Institute of Electrical and Electronics Engineers (IEEE), 2023Conference paper (Refereed)
    Abstract [en]

    A double-layer lens consists of a pair of rotationally symmetric index profiles or geodesic lens shapes connected by a reflecting mirror partially covering their common periphery. Such a lens can provide a focus in each layer, and a wave travelling between the foci explores both layers. Here, we concentrate on the case with one layer being homogeneous or flat, and derive a general solution for the lens profiles by solving a Luneburg-like inverse problem with pre-specified foci inside or outside the lens, and different background indices in two layers. We demonstrate four examples of interest in ray-tracing plots. These lenses may find application in communications, sensing, and imaging from millimeter waves up to the optical bands.

  • 43.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Horsley, Simon A. R.
    Univ Exeter, Dept Phys & Astron, Stocker Rd, Exeter EX4 4QL, Devon, England..
    Fonseca, Nelson J. G.
    European Space Agcy, Antenna & Sub Millimetre Waves Sect, NL-2200 AG Noordwijk, Netherlands..
    Tyc, Tomas
    Masaryk Univ, Fac Sci, Inst Theoret Phys & Astrophys, Kotlarska 2, Brno 61137, Czech Republic..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Double-layer geodesic and gradient-index lenses2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 2354Article in journal (Refereed)
    Abstract [en]

    A double-layer lens consists of a first gradient-index/geodesic profile in an upper waveguide, partially surrounded by a mirror that reflects the wave into a lower guide where there is a second profile. Here, we derive a new family of rotational-symmetric inhomogeneous index profiles and equivalent geodesic lens shapes by solving an inverse problem of pre-specified focal points. We find an equivalence where single-layer lenses have a different functionality as double-layer lenses with the same profiles. As an example, we propose, manufacture, and experimentally validate a practical implementation of a geodesic double-layer lens that is engineered for a low-profile antenna with a compact footprint in the millimeter wave band. Its unique double-layer configuration allows for two-dimensional beam scanning using the same footprint as an extension of the presented design. These lenses may find applications in future wireless communication systems and sensing instruments in microwave, sub-terahertz, and optical domains. A double-layer lens consists of a first gradient-index/geodesic profile in an upper waveguide, partially surrounded by a mirror that reflects the wave into a lower guide where there is a second profile. A family of such lens profiles are derived.

  • 44.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, ETS Ingn Informat, Seville 41012, Spain..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Yin, Xiaoxing
    Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Efficient Leaky-Lens Antenna at 60 GHz Based on a Substrate-Integrated-Holey Metasurface2020In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 68, no 12, p. 7777-7784Article in journal (Refereed)
    Abstract [en]

    We propose a low-cost implementation of a low-dispersive leaky-wave antenna (LWA) at 60 GHz for point-to-point 5G communications. The LWA is implemented with glide-symmetric holes in gap-waveguide technology. The radiation is produced through a slit and controlled with glide-symmetric holes. The low dispersion is achieved thanks to the use of a dispersive prism that compensates the frequency dependence of the radiation through the slit. The main innovation of our proposed design is the use of substrate integrated holes (SIHs) to implement the dispersive prism. This implementation significantly enhances the bandwidth and improves the robustness to manufacturing tolerances. Also, this implementation reduces the cost of the antenna while maintaining low losses since the majority of the propagation inside the prism is in air. Additionally, we demonstrate that the use of glide-symmetric holes in the slit allows for a better control of the amount of radiation (attenuation constant) when compared with conventional holes. The differences in the attenuation constant between conventional and glide-symmetric holes have been studied with a multimodal analysis. Apart from giving a convenient physical insight, this method also expedites the design process.

  • 45.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, ETS Ingn Informat, Dept Appl Phys 1, Seville 41004, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dispersion Analysis of Glide-Symmetric Holey Metasurface Based on Multimodal Transfer-Matrix Approach2021In: 2021 15th European conference on antennas and propagation (EUCAP), Institute of Electrical and Electronics Engineers (IEEE) , 2021Conference paper (Refereed)
    Abstract [en]

    The dispersion behaviors of a glide-symmetric holey metasurface is investigated, with special interest in its stopband attenuation. The unit cell of the periodic surface is described by its multimodal transfer matrix in order to account for the higher-order modal couplings between adjacent cells. This multimodal transfer matrix is obtained from the generalized scattering matrix (simulated by CST) that relates multiple modes on each cell boundary. Then, the complex modal wavenumbers (both the phase and attenuation constants) are calculated from a generalized eigenprohlem. This simulation-aided approach proves to be a highly efficient and very accurate tool for the Bloch analysis of glide-symmetric metasurfaces. Additionally, it enables the study of some unnoticed phenomena that cannot be captured by a commercial eigenmode simulator; among them, the existence of complex modes and the anisotropy in the stopbands. The reported findings can be beneficially employed for the design of such glide-symmetric holey surface as an EBG for gap-waveguide technology.

  • 46.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Universidad de Sevilla, 41012 Seville, Spain.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Enhanced Leaky-Lens Antenna at V-band Using Substrate-Integrated-Holey Metasurface2021In: 2021 International Conference on Electromagnetics in Advanced Applications, ICEAA 2021, Institute of Electrical and Electronics Engineers (IEEE) , 2021, p. 268-269Conference paper (Refereed)
    Abstract [en]

    Leaky-wave antennas (LWAs) have gained increasing attraction in communications systems, especially at mmWave band due their high gain, low profiles, and simple feeding networks. However, their application in these systems has been limited due to their inherent dispersive nature that causes gain losses at the fixed angle. Although attempts have been made to overcome this limitation, the existing solutions often suffer from either drop in directivity, prohibitive complexity, or higher losses. To overcome these drawbacks, the proposed solutions include the use of a frequency-dependent Huygens metasurface to reduce the beam squint by nearly half [C.Pfeiffer and A.Grbic, IEEE Trans.Antennas Propag., 63, 7, 3248-3253, 2015], or a complementary-dispersive prism lens to achieve an almost complete cancellation [L.Wang, J.L.Gomez-Tornero and O.Quevedo-Teruel, IEEE Trans.Antennas Propag., 66, 6, 3110-3118, 2018]. Even though these two schemes are similar in concept, the latter is more flexible and can be applied to a larger number of LWAs. The prism solution has been experimentally demonstrated with pin- and hole-type groove-gap waveguide (GGW) technology at X- and V-band.

  • 47.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, Seville, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Ray-Tracing Analysis of Double-Layer Geodesic Lens Antenna2022In: 2022 International Symposium On Antennas And Propagation (ISAP), Institute of Electrical and Electronics Engineers (IEEE) , 2022, p. 197-198Conference paper (Refereed)
    Abstract [en]

    A double-layer geodesic lens consists of two layers of flat or curved parallel-plate waveguides, connected by a mirror over part of their common periphery. Such a device can provide one focus on each layer, and a wave is transformed across layers between the two foci. When one of the foci is at infinity, the lens can be used as an antenna that permits a direct extension for two-dimensional scanning with low scan losses. Here, we carry out a ray-tracing analysis of a rotationally symmetric double-layer geodesic lens antenna with one of its two layers being flat. The proposed model demonstrates good computational efficiency and agrees well with the simulated/measured results.

  • 48.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Mesa, Francisco
    Univ Seville, Dept Appl Phys ETS Ingn Informat 1, Seville 41004, Spain..
    Yin, Xiaoxing
    Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Accurate Characterization and Design Guidelines of Glide-Symmetric Holey EBG2020In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 68, no 12, p. 4984-4994Article in journal (Refereed)
    Abstract [en]

    The dispersion characteristics of a glide-symmetric holey periodic surface are investigated, with special emphasis on a detailed study of its stopbands. The unit cell is modeled as a multiport network associated with multiple modes at each of the lattice boundaries. Enforcing the periodic conditions, the real and imaginary parts of the wavenumbers of the Floquet modes are calculated through an eigenproblem posed in terms of the generalized multimodal transfer matrix, which is computed from the scattering parameters obtained with a full-wave simulator. This procedure allows us to take into account the higher order modal couplings between adjacent unit cells that are crucial for accurate dispersion analysis. The resulting simulation-assisted approach provides both a convenient computational tool and a very fruitful physical insight that reveals the existence of complex modes, the convergence of opposite-parity modes, and the anisotropy in both passband and stopband. This approach enables a precise calculation of the attenuation constant, which is not possible with conventional techniques as the eigenmode solvers of commercial software. Based on this approach, an extensive parametric study is carried out, rigorously establishing a set of critical criteria for the use of such a periodic surface as an electromagnetic bandgap structure in gap waveguide technology. Moreover, the analysis of the directional properties of the structure is applied to further suppress the leakage.

  • 49.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Valerio, G.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dispersion analysis of polar glide symmetry with coaxial rings2018In: IET Conference Publications, Institution of Engineering and Technology , 2018, no CP741Conference paper (Refereed)
    Abstract [en]

    In this article, the dispersion properties of a coaxial transmission line with polar glide-symmetric rings are analyzed. This symmetry is obtained by introducing periodic polar rings on either the inner or outer conductor of a coaxial guide. By modifying the relative radii of both rings, we demonstrate that a zero bandgap with non-zero group velocity at the Brillouin zone boundary can be achieved. Such quasi-linear dispersion is analyzed by applying both a circuit-based method and full-wave simulations. A good agreement is achieved between the methods.

  • 50.
    Chen, Qiao
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Zetterström, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Dept Appl Phys 1, ETS Ingn Informat, Seville 41004, Spain..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Palomares-Caballero, Angel
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, Granada 18071, Spain..
    Pucci, Elena
    Ericsson AB, Stand & Technol, S-16440 Stockholm, Sweden..
    Yin, Xiaoxing
    Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Prism-based Leaky-Lens Antennas at 60 GHz for 5G Point-to-Point Communication Links2020In: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    Two cost-effective implementations of a leaky-lens antenna at 60 GHz are proposed for high-throughput 5G communication links. The leaky-wave feed is realized in gap-waveguide technology, where the radiation from the slit is controlled with glide-symmetric holes. The beam-squint of the leaky-wave radiation is mitigated, owing to the coupling of a complementary dispersive prism. Here, two prisms are implemented, one with glide-symmetric holes, and another with substrate-integrated holes (SIHs), both integrated in parallel plates with the leaky wave feeding. Thanks to glide symmetry, better control of the leakage rate, lower costs, and better tolerance to manufacturing are achieved in comparison with the non-glide holey counterpart. In addition, the SIH-based design exhibits a substantially enhanced bandwidth with even better robustness. In the analysis of the leaky-wave feed, more accuracy and reduced computational time is achieved by using a multi-mode method. Both antennas show stable radiation patterns, featuring high efficiency, high gain, and low side lobe levels.

12345 1 - 50 of 238
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf