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• 1.
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.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion. Univ Seville, Microwaves Grp, Dept Appl Phys 1, Escuela Tecn Super Ingn Informat, E-41012 Seville, Spain.. Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain.. Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Wave Propagation in Periodic Metallic Structures with Equilateral Triangular Holes2020Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 10, nr 5, artikel-id 1600Artikel i tidskrift (Refereegranskat)

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.

• 2.
Sorbonne Univ, L2E, UR2, F-75005 Paris, France..
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Sorbonne Univ, L2E, UR2, F-75005 Paris, France..
Bloch Analysis of Artificial Lines and Surfaces Exhibiting Glide Symmetry2019Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 67, nr 7, s. 2618-2628Artikel i tidskrift (Refereegranskat)

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.

• 3.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Additive Manufactured Three Dimensional Luneburg Lens for Satellite Communications2019Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, artikel-id 8739803Konferensbidrag (Refereegranskat)

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.

• 4.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Wireless Sensor Network Utilizing Radio-Frequency Energy Harvesting for Smart Building Applications2018Ingår i: IEEE Antennas & Propagation Magazine, ISSN 1045-9243, E-ISSN 1558-4143, Vol. 60, nr 5, s. 124-136Artikel i tidskrift (Refereegranskat)

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.

• 5.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Additive manufactured dielectric Gutman lens2019Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 55, nr 25, s. 1318-1320Artikel i tidskrift (Refereegranskat)

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.

• 6.
Ericsson AB, Ericsson Res, Gothenburg, Sweden..
Ericsson AB, Ericsson Res, Gothenburg, Sweden.. Ericsson AB, Ericsson Res, Gothenburg, Sweden.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Implementation of a compact Ka-band parallel plate Luneburg lens based on a hybrid dielectric/metasurface unit cell2019Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019, IEEE, 2019, artikel-id 8740306Konferensbidrag (Refereegranskat)

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.

• 7.
Ericsson AB, Ericsson Res, Gothenburg, Sweden. attsson, Martin; Quevedo-Teruel, Oscar.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
A Ka-band glide-symmetric planar Luneburg lens with combined electric/metasurface for 5G communications2018Ingår i: 2018 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)

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.

• 8. Camacho, Miguel
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Designer surface plasmon dispersion on a one-dimensional periodic slot metasurface with glide symmetry2017Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 42, nr 17, s. 3375-3378Artikel i tidskrift (Refereegranskat)

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.

• 9. Camacho, Miguel
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Mimicking glide symmetry dispersion with coupled slot metasurfaces2017Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, nr 12, artikel-id 121603Artikel i tidskrift (Refereegranskat)

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.

• 10.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Southeast Univ, State Key Lab Millimeter Wave, Nanjing 210096, Jiangsu, Peoples R China..
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Dispersion Analysis of Coaxial Line Loaded with Twist-Symmetric Half-Rings2018Ingår i: 2018 IEEE International Workshop on Antenna Technology, iWAT2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)

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.

• 11.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Jiangsu, Peoples R China.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Sorbonne Univ, Lab Elect & Electromagnetisme, F-75005 Paris, France.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Modeling and Dispersion Analysis of Coaxial Lines With Higher Symmetries2018Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 66, nr 10, s. 4338-4345Artikel i tidskrift (Refereegranskat)

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.

• 12.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Dispersion analysis of polar glide symmetry with coaxial rings2018Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2018, nr CP741Konferensbidrag (Refereegranskat)

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.

• 13.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion. Southeast Univ, State Key Lab Millimeter Waves, Nanjing 210096, Peoples R China.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik. Ericsson AB, Syst & Technol, S-16440 Stockholm, Sweden.. Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18001 Granada, Spain.. Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18001 Granada, Spain.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Glide-Symmetric Holey Leaky-Wave Antenna With Low Dispersion for 60 GHz Point-to-Point Communications2020Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 68, nr 3, s. 1925-1936Artikel i tidskrift (Refereegranskat)

In this article, two novel efficient leaky-wave antennas (LWAs) with stable radiation patterns operating in the 60 GHz band are proposed. The LWAs are implemented in groove-gap waveguide (GGW) technology. To mitigate the beam squint due to the dispersive nature of LWAs, complementary-dispersive prisms are coupled to the LWA radiation aperture. The antennas are implemented in fully metallic purely holey periodic structures, resulting in a more cost-effective and robust manufacturing process compared to previously reported pin-based structures. Two prisms are proposed, one with mirror symmetry and one with glide symmetry. When the prism possesses a glide symmetry, much fewer holes are required while maintaining a similar performance, which even further decreases the fabrication costs. The complex propagation constant is optimized for low sidelobe levels (SLLs) with tailored hole diameters and waveguide dimensions, thus for the first time demonstrating the capability of using glide-symmetric holes to control the leakage rate. Two prototypes with mirror- and glide-symmetric prisms are theoretically synthesized and validated by the simulated and experimental results. A frequency bandwidth of 11% is achieved for both prototypes with the beam squint within +/- 0.9 degrees (mirror) and +/- 1.7 degrees (glide), SLLs below -15 dB (mirror) and -13 dB (glide), total efficiency almost 90%, and realized gain of 17 +/- 0.5 dB at a fixed observing angle. The developed antennas are intended for mm-wave point-to-point communications.

• 14. Chen, Z. -L
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Artificial maxwell fisheye lens design and synthesis with using metasurface structure2015Ingår i: 2015 International Workshop on Electromagnetics: Applications and Student Innovation Competition, iWEM 2015, Institute of Electrical and Electronics Engineers Inc. , 2015Konferensbidrag (Refereegranskat)

In this paper, we use a periodic structure to produce a Maxwell's fisheye lens and investigate some important information such as power, efficiency, etc. At Chapter 1, we describe some introduction about the surface plasmon polariton (SPP), frequency selective surface (FSS), concentration power by using lens. At Chapter 2, we describe some theorem about we need to use like Transmission line modal, high impedance surface, periodic structure lens. At Chapter 3, we describe our design and we show some simulation results about the surface wave Maxwell's fisheye lens. At chapter 4, we discuss our results about the fisheye lens. At chapter 5, we will draw the conclusions. © 2015 IEEE.

• 15.
KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Reducing the Dispersion of Periodic Structures with Twist and Polar Glide Symmetries2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 10136Artikel i tidskrift (Refereegranskat)

In this article, a number of guiding structures are proposed which take advantage of higher symmetries to vastly reduce the dispersion. These higher symmetries are obtained by executing additional geometrical operations to introduce more than one period into the unit cell of a periodic structure. The specific symmetry operations employed here are a combination of p-fold twist and polar glide. Our dispersion analysis shows that a mode in a structure possessing higher symmetries is less dispersive than in a conventional structure. It is also demonstrated that, similar to the previously studied Cartesian glide-symmetric structures, polar glide-symmetric structures also exhibit a frequency independent response. Promising applications of these structures are leaky-wave antennas which utilize the low frequency dependence.

• 16.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Sorbonne Univ, Lab Electron & Electromagnetisme, F-75005 Paris, France.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Propagation characteristics of periodic structures possessing twist and polar glide symmetries2019Ingår i: EPJ Applied Metamaterials, ISSN 2272-2394, Vol. 6, artikel-id 14Artikel i tidskrift (Refereegranskat)

In this article, we provide an overview of the current state of the research in the area of twist symmetry. This symmetry is obtained by introducing multiple periods into the unit cell of a periodic structure through a rotation of consecutive periodic deformations around a symmetry axis. Attractive properties such as significantly reduced frequency dispersion and increased optical density, compared to purely periodic structures, are observed. The direct link between the symmetry order and these properties is illustrated through numerical simulations. Moreover, polar glide symmetry is introduced, and is shown to provide even further control of the dispersion properties of periodic structures, especially when combined with twist symmetry. Twist symmetries can, with benefit, be employed in the development of devices for future communication networks and space applications, where fully metallic structures with accurate control of the dispersion properties are desired.

• 17.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Fully-metallic, Low-dispersive, Leaky-wave Fed Lens Antenna for 60 GHz Base Station Applications2018Ingår i: 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena, METAMATERIALS 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 90-92Konferensbidrag (Refereegranskat)

The guiding structure commonly employed in leaky-wave antennas is dispersive, resulting in beam-steering with frequency. This behavior reduces operational bandwidth in point-to-point communication applications. In this work, we present an approach that aims at increasing the operational bandwidth of leaky-wave antennas by the employment of a metasur-face lens.

• 18.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Ericsson AB, Syst & Technol, S-16480 Stockholm, Sweden.. Hamburg Univ Technol, Inst Theoret Elektrotech, D-21079 Hamburg, Germany.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Low-Dispersive Glide-Symmetric Leaky-Wave Antenna at 60 GHz2019Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019, IEEE, 2019, artikel-id 8740212Konferensbidrag (Refereegranskat)

In this work we demonstrate a method for producing low-loss, non-squinting, directive leaky-wave antennas (LWAs) for millimeter-wave frequencies. The scanning behaviour of the radiation pattern arises from the dispersive nature of the waveguide mode, which is leaking out when opening the wave guiding structure. We propose a method to cancel the dispersive behaviour, by allowing the leaked waves to refract in a dispersive prism-lens. The proposed method allows for fully metallic implementation of the antenna, resulting in low losses. Furthermore, high directivity is easily achieved with a simple feeding. The corresponding theory is outlined, and the proposed method is used to design an antenna operating at 60 GHz. The obtained bandwidth, with less than 1 degrees beam scanning, is 20% in simulations and the realized gain of the antenna is 17 dB across the entire bandwidth. The design is proposed as an alternative to obtain high gain antennas for 5G applications, in which low losses and narrow beams are expected to be key features for mm-waves.

• 19.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Ericsson AB, Syst & Technol, S-16480 Stockholm, Sweden.. Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain.. Hamburg Univ Technol, Inst Theoret Elektrotech, D-21079 Hamburg, Germany.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Low-Dispersive Leaky-Wave Antennas for mmWave Point-to-Point High-Throughput Communications2020Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 68, nr 3, s. 1322-1331Artikel i tidskrift (Refereegranskat)

In this article, we present two efficient leaky-wave antennas (LWAs) with stable radiation pattern, operating at 60 GHz. Both antennas exhibit attractive properties such as significantly reduced beam-squint, low loss, low sidelobes, high directivity, and simple manufacturing. The beam-squint of conventional LWAs is reduced by refracting the leaked waves in a dispersive lens and the low sidelobe levels are achieved by tapering the leakage rate along the aperture. Since the antennas are implemented in groove gap waveguide technology, the losses are low. The two antennas are different in terms of their asymmetric/symmetric leakage tapering with respect to the broadside direction. Both designs are optimized for low sidelobes, but since symmetry is enforced in one, the resulting performance in terms of sidelobes is suboptimal. However, in the symmetric design, multiple stable beams can be obtained, simultaneously or independently. Twenty percent bandwidth is obtained with less than +/- 0.5 degrees beam-squint. In this frequency range, the gain is stable at 17 and 15 dBi for the asymmetric and symmetric designs, respectively. The designs are intended for point-to-point links in mmWave communication networks where low losses, directive beams, and low sidelobes are expected to be key features.

• 20. Dahlberg, Oskar
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Accurate and low-dispersive control of refractive properties in fully metallic waveguides possessing twist symmetry2018Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2018, nr CP741Konferensbidrag (Refereegranskat)

We here present a method of reducing the dispersive nature of periodic structures by utilizing twist symmetries. A dispersion study of four different 1D periodic structures is conducted to present the advantage of structures possessing twist symmetries. The analysis shows a clearly reduced frequency dependence of twist-symmetric structures, compared to more simple periodic structures. Additional advantage provided by twist symmetries is the accurate control of the refractive properties of the structures. Promising applications of twist-symmetric guiding structures are leaky-wave antennas, filters and phase shifters.

• 21.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Sorbonne Univ, Lab Elect & Electromagnetisme, F-75005 Paris, France.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Fully Metallic Flat Lens Based on Locally Twist-Symmetric Array of Complementary Split-Ring Resonators2019Ingår i: Symmetry, ISSN 2073-8994, E-ISSN 2073-8994, Vol. 11, nr 4, artikel-id 581Artikel i tidskrift (Refereegranskat)

In this article, we demonstrate how twist symmetries can be employed in the design of flat lenses. A lens design is proposed, consisting of 13 perforated metallic sheets separated by an air gap. The perforation in the metal is a two-dimensional array of complementary split-ring resonators. In this specific design, the twist symmetry is local, as it is only applied to the unit cell of the array. Moreover, the twist symmetry is an approximation, as it is only applied to part of the unit cell. First, we demonstrate that, by varying the order of twist symmetry, the phase delay experienced by a wave propagating through the array can be accurately controlled. Secondly, a lens is designed by tailoring the unit cells throughout the aperture of the lens in order to obtain the desired phase delay. Simulation and measurement results demonstrate that the lens successfully transforms a spherical wave emanating from the focal point into a plane wave at the opposite side of the lens. The demonstrated concepts find application in future wireless communication networks where fully-metallic directive antennas are desired.

• 22. Diallo, C. D.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Parallel-plate-waveguide luneburg lens through a holey plate metasurface2015Ingår i: 2015 9th European Conference on Antennas and Propagation, EuCAP 2015, IEEE , 2015Konferensbidrag (Refereegranskat)

This paper presents a parallel plate waveguide (PPW) Luneburg lens designed using an array of subwavelength circular holes etched on a metallic plate printed on a dielectric substrate. Variation of the hole radius modulates the effective permittivity. The lens operates in the Ka band of frequencies in a quasi-TEM mode. Easy to implement and low cost, the lens could be a good candidate as a lens-like beamformer for low loss multiple beam applications.

• 23.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Ericsson AB, Ericsson Res, S-41756 Gothenburg, Sweden.. Ericsson AB, Ericsson Res, S-41756 Gothenburg, Sweden.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Using Glide-Symmetric Holes to Reduce Leakage Between Waveguide Flanges2018Ingår i: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 28, nr 6, s. 473-475Artikel i tidskrift (Refereegranskat)

In this letter, a novel cost-effective flange is proposed to prevent the leakage created by undesired air gaps between flanges of two mating waveguides. The cause of an undesired gap can be surface curvature, dirt, human mistakes, or misalignment. Our proposal consists of machining glide-symmetric holes around the waveguide aperture on the flanges. Due to the glide symmetry properties, an identical pattern of the holes is possible at both sides, thus becoming glide-symmetric when they are mated together.

• 24.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Univ Oviedo, Dept Elect Engn, Gijon 33003, Spain.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Wide-Angle Impedance Matching Using Glide-Symmetric Metasurfaces2020Ingår i: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 30, nr 1, s. 8-11Artikel i tidskrift (Refereegranskat)

This letter demonstrates that glide symmetry can be used to match the impedance of highly dense dielectric profiles in wide angle and broad bandwidth. Using glide-symmetric metasurfaces permits tuning the magnetic properties of materials, so high values of permittivity can be matched to free space in wideband. This matching is achieved without disturbing the performance of the device, since the refractive index remains fixed. The performance of the proposed matching method is validated through measurements for normal incidence. For oblique incidence, a hyperbolic dielectric lens is matched with glide-symmetric structures in simulations. These simulations demonstrate a smooth transmission of the fields, manifesting a well-matched profile of the lens.

• 25.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Univ Exeter, Dept Phys & Astron, Exeter EX4 4QL, Devon, England.. KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Lens Antennas Using QCTO Technique2015Ingår i: 2015 USNC-URSI RADIO SCIENCE MEETING (JOINT WITH AP-S SYMPOSIUM) PROCEEDINGS, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 168-168Konferensbidrag (Refereegranskat)
• 26.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
A bespoke lens for a slot log-spiral excitation2018Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2018, nr CP741Konferensbidrag (Refereegranskat)

In this paper, a bespoke lens has been designed for a slot log-spiral excitation. The performance of this lens is compared with a conventional hyper-hemispherical lens. Using the bespoke lens methodology, the specific electromagnetic properties of the slot log-spiral excitation are obtained and its phase fronts are transformed to flat phase fronts by a QCTO (quasi-conformal transformation optics) technique. The performance of the lenses is evaluated with the radiation properties. The bespoke lens produces an improvement in terms of directivity and side lobe levels.

• 27.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Bespoke Lenses Based on Quasi-Conformal Transformation Optics Technique2017Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, nr 5, s. 2256-2264Artikel i tidskrift (Refereegranskat)

In this paper, a systematic method to design a quasioptimum lens profile based on quasi-conformal transformation optics technique for a given excitation is presented. This method is applied to a number of conventional antennas, such as an aperture and a log-spiral slot. In all these configurations, an increase of the directivity is observed. Furthermore, using this method, a quasi-optimum graded index lens for a broadband enhanced leaky slot excitation is designed and the results are compared with a hyperhemispherical lens with and without matching layers. Our proposed methodology demonstrates to be able to increase the directivity, to reduce the sidelobes and the cross polarization in a broad bandwidth from 20 to 70 GHz. Due to the continuously changed dielectric constant of the lens profile, reflections are also reduced considerably inside the lens.

• 28.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Contact-less Measurement by Using Glide-symmetric Holes on Flanges2018Ingår i: 2018 12TH INTERNATIONAL CONGRESS ON ARTIFICIAL MATERIALS FOR NOVEL WAVE PHENOMENA (METAMATERIALS), IEEE , 2018, s. 105-107Konferensbidrag (Refereegranskat)

We present a cost-effective solution for contact-less measurement of waveguiding structures at high frequencies. Drilling glide-symmetric holey EBG (electromagnetic band gap) on the flanges, the leakage caused by undesired air-gaps, by the result of human mistakes or instrumental errors, between the flanges can be minimized considerably and contact-less measurement becomes possible.

• 29.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Ultrawideband Anisotropic Glide-Symmetric Metasurfaces2019Ingår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 18, nr 8, s. 1547-1551Artikel i tidskrift (Refereegranskat)

This letter presents a method to realize anisotropic two-dimensional designs with wideband operation. Glide symmetry has been proven to increase the bandwidth and equivalent refractive index of periodic structures. Here, two anisotropic glide-symmetric unit cells are proposed and characterized. Our simulated results prove that these unit cells follow the general behavior of periodic structures possessing glide symmetry. Moreover, we demonstrate that higher level of anisotropy can also be achieved by glide symmetry. Combining our proposed anisotropic glide-symmetric unit cell and transformation optics, a 30% compressed Luneburg lens is designed. The lens operates from 1 to 13 GHz.

• 30.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Broadband Planar Leaky Wave Antenna Using Glide-symmetric Meandered Transmission LineManuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
• 31.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Design of microwave components in groove gap waveguide technology implemented by holey EBG2017Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 746-748, artikel-id 7928587Konferensbidrag (Refereegranskat)

In this paper, the feasibility of the implementation of microwave components in groove gap waveguide technology by glide-symmetry holey EBG is discussed. Using this technology, microwave components and antennas which were previously designed for hollow metallic waveguides can be manufactured in a cost-effective way at high frequencies. To show the viability of the proposed solution a phase shifter and a mode converter are designed as examples of typical components for antenna systems.

• 32.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Design Guidelines for Gap Waveguide Technology Based on Glide-Symmetric Holey Structures2017Ingår i: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 27, nr 6, s. 542-544Artikel i tidskrift (Refereegranskat)

The behavior of a glide-symmetric holey periodic structure as electromagnetic bandgap is studied in this letter. A number of numerical simulations have been carried out in order to define the importance of each constituent parameter of the unit cell. Our proposed structure finds potential application in antennas and circuits based on gap waveguide technology for the millimeter band. The experimental verifications confirm the effects previously analyzed with the numerical studies.

• 33.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Wideband glide-symmetric holey structures for gap-waveguide technology2017Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1658-1660, artikel-id 7928356Konferensbidrag (Refereegranskat)

In this paper, the stop-band of two different holey glide-symmetric EBG lattices is studied. The results show that glide-symmetric EBG structures have potential to achieve wide stop-bands by polygonal lattices. Potential application of the proposed EBG structure in gap-waveguide technology is discussed in the second part of the paper.

• 34.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Low-cost metasurface using glide symmetry for integrated waveguides2016Ingår i: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, artikel-id 7481261Konferensbidrag (Refereegranskat)

A novel Electromagnetic Band Gap (EBG) structure based on an off-shifted periodic metasurface is presented here. This technique can be employed for packaging of electrical circuits and gap waveguide technology. The proposed structure is easy to manufacture since it only requires drilling holes in metallic plates, reducing the cost when compared to previous works based on other textured surfaces.

• 35.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Cost-Effective Gap Waveguide Technology Based on Glide-Symmetric Holey EBG Structures2018Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 66, nr 2, s. 927-934Artikel i tidskrift (Refereegranskat)

We present a novel electromagnetic bandgap (EBG) structure, which can be used to manufacture low-cost waveguiding structures at high frequencies. The unit cell of the proposed EBG consists of glide-symmetric holes in parallel plate waveguide. Using this unit cell in groove gap waveguide technology has a number of advantages over pin-type EBG at high frequencies, such as acquiring higher accuracy because of larger periodicity as well as an easier and cheaper manufacturing process. The performance of the proposed waveguiding structure is demonstrated using both a straight and a double 90 degrees bent lines through simulation and measurement.

• 36.
Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Razavi Khorasan, Iran.. Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Razavi Khorasan, Iran.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Elliptical generalized Maxwell fish-eye lens using conformal mapping2019Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 21, artikel-id 063010Artikel i tidskrift (Refereegranskat)

A circular graded index lens is conformally transformed to an elliptical shape using a closed-form transformation. The proposed transformation is then employed to compress a Maxwell fish-eye and its generalized version. Since the transformation is conformal, the electromagnetic properties of the device are perfectly preserved after the transformation with fully isotropic and dielectric-only materials. Ray-tracing and full-wave simulations are carried out for several cases to verify the functionality of the optically transformed lenses in geometrical optics and wave optics regimes.

• 37.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Razavi Khorasan, Iran.. Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Razavi Khorasan, Iran..
Design of Nonmagnetic All-mode Waveguide Coupler with Perfect Transmission Using Transformation Optics2019Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, artikel-id 8739511Konferensbidrag (Refereegranskat)

Using the transformation optics method together with the basic properties of Maxwell equations, a compact nonmagnetic waveguide coupler is designed that can ideally couple all TMn modes. Two compression functions are proposed to provide a perfect smooth transition between the waveguides. This coupler can be used to guide and compress a vacuumfilled waveguide to a smaller waveguide with a predefined higher dielectric constant inside. The design method is validated by simulated examples using COMSOL Multiphysics.

• 38.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Iran.. Ferdowsi Univ Mashhad, Dept Elect Engn, Mashhad, Iran..
Transformation optics for perfect two-dimensional non-magnetic all-mode waveguide couplers2019Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 9, nr 3, s. 1320-1332Artikel i tidskrift (Refereegranskat)

Here, we demonstrate that transformation optics can be used to produce 2-D non-magnetic waveguide couplers with no reflections. Our approach consists of using a scaling function for reflection suppression and introducing an auxiliary function in the transformation optics formulation to achieve a non-magnetic medium for coupling the TM polarization. To demonstrate the potential of this method, two non-magnetic waveguide couplers are designed. The first one satisfies the Brewster angle condition for any arbitrary incidence angle (TMn modes), extending the performance of couplers previously reported in the literature that only operate for TEM (TM0 mode), i.e. waves with normal incidence. Our method can be applied to match any given dielectric constant. Our results demonstrate that for a given mode (angle), we achieve a perfect match to a defined dielectric constant. The second design removes the dependence of the reflectionless condition to the incident angle at the boundary. Hence, this coupler works for all incident angles (TMn modes). It is used to compress all the modes into a region with a higher predefined refractive index.

• 39.
European Space Agcy, Antenna & Sub Millimetre Waves Sect, Noordwijk, Netherlands. iao, Qingbi; Quevedo-Teruel, Oscar.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
The Water Drop Lens: A Modulated Geodesic Lens Antenna Based on Parallel Curves2018Ingår i: ISAP 2018 - 2018 International Symposium on Antennas and Propagation, Institute of Electrical and Electronics Engineers (IEEE), 2018, artikel-id 8627878Konferensbidrag (Refereegranskat)

This paper discusses the design of parallel plate waveguide geodesic nses based on parallel curves enabling low-profile beamformers with a ry wide angular scanning range. The proposed approach provides smooth ns profiles with additional degrees of freedom for the optimization of odesic lenses, enabling Gaussian beam but also shaped patterns. The tational symmetry of the lens results in a shape looking like water op ripples, also known as capillary waves, at the surface of a fluid, nce the water drop lens appellation.

• 40.
European Space Agcy, Antenna & Submillimetre Wave Sect, Noordwijk, Netherlands..
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
The Water Drop Lens: a Low-Profile Geodesic Parallel Plate Waveguide Lens Antenna for Space Applications2019Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, artikel-id 8739805Konferensbidrag (Refereegranskat)

This paper introduces the design of a parallel plate waveguide geodesic lens modulated with spline functions. This geodesic lens design is rotational-symmetric, which naturally provides a high pattern stability over a wide angular range. The proposed design is thoroughly compared to the reference Rinehart-Luneburg lens and numerical results indicate similar electromagnetic performance, including scattering parameters and radiation, while enabling a height reduction by a factor of 2.6. This beamformer provides very wide angular scanning up to +/- 70 degrees with scan losses below 3 dB. The lens can be designed to provide very high aperture efficiency (between 80 and 90%) over a wide frequency operating range. Analyses were performed over the frequency range 26-32 GHz, demonstrating very stable performance. The very smooth shape of the lens is particularly attractive for applications at millimeter and sub-millimeter wavelengths.

• 41.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Mode matching analysis of two dimensional glide-symmetric corrugated metasurfaces2017Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 749-751, artikel-id 7928533Konferensbidrag (Refereegranskat)

The mode matching method for analysing two dimensional doubled corrugated metasurfaces, including glide-symmetric corrugated metasurfaces, embedded in a thin parallel plate waveguide is presented. This method is accurate, fast, and without any limitations on the parameters.

• 42.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Dispersion Analysis of 2-D Glide-Symmetric Corrugated Metasurfaces Using Mode-Matching Technique2018Ingår i: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 28, nr 1, s. 1-3Artikel i tidskrift (Refereegranskat)

In this letter, wave propagation in 2-D doubled corrugated metasurfaces, including glide-symmetric corrugated metasurfaces, embedded in a thin parallel plate waveguide have been analyzed using the mode matching method. The general dispersion equation for propagation at different directions is derived and dispersion surfaces have been obtained for three different cases. The results are in good agreement with reference results obtained using CST Microwave Studio. Moreover, the method is accurate and computationally much faster than CST Microwave Studio and similar commercial software.

• 43.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Twist and Polar Glide Symmetries: an Additional Degree of Freedom to Control the Propagation Characteristics of Periodic Structures2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8Artikel i tidskrift (Refereegranskat)

New high-frequency 5G and satellite communication systems require fully-metallic antennas and electromagnetic components. These components can be implemented with truncated versions of periodic structures. In order to achieve the desired performance of these future devices, it is of crucial importance to have a precise control of the propagation properties, i.e. the frequency dispersion behavior and stop-bands. Here, we demonstrate the potential use of higher symmetries to diminish the frequency dispersion of periodic structures and control the width of stop-bands with a new type of fully-metallic transmission line, which is loaded with holes on a twist-symmetric configuration. Simulated and experimental results confirm the intrinsic link between the propagation characteristics and the symmetries of a periodic structure. Additionally, we provide a definitive explanation of the recently discovered polar glide symmetry and its potential combination with twist symmetries to produce low-dispersive materials and reconfigurable stop-bands. The promising properties of these structures are demonstrated with a fully-metallic reconfigurable filter, which could be used for future high-frequency 5G and satellite communication systems.

• 44.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Mimicking Twist Symmetry Properties in Flat Structures2019Ingår i: 13th European Conference on Antennas andPropagation (EUCAP), Institute of Electrical and Electronics Engineers (IEEE), 2019Konferensbidrag (Refereegranskat)

Twist symmetry provides an additional degree of freedom to control the wave propagation in periodic structures. However, real twist-symmetric structures are cylindrical structures that have a high cost of manufacturing. In addition, they are not compatible with the available, low-cost and flat technologies, such as microstrip technology. Here, we investigate the possibility of mimicking the dispersion properties of twist symmetry in flat structures.

• 45.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Analysis of wave propagation in plasmonic holey metasurfaces with cylindrical holes2018Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2018, nr CP741Konferensbidrag (Refereegranskat)

The wave propagation along a plasmonic holey metasurface when a metallic plate is located in its proximity has been analyzed using a mode matching technique. With this analysis, we demonstrate that decreasing the distance between the metallic plate and the holey surface excites nonresonant higher order modes in the structure. Therefore, considering only the dominant mode inside the holes, as the previous simpler models assumed, is not sufficient to analyze this type of metasurfaces.

• 46. Horsley, S. A. R.
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
Removing singular refractive indices with sculpted surfaces2014Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, s. 4876-Artikel i tidskrift (Refereegranskat)

The advent of Transformation Optics established the link between geometry and material properties, and has resulted in a degree of control over electromagnetic fields that was previously impossible. For waves confined to a surface it is known that there is a simpler, but related, geometrical equivalence between the surface shape and the refractive index, and here we demonstrate that conventional devices possessing a singularity-that is, the requirement of an infinite refractive index-can be realised for waves confined to an appropriately sculpted surface. In particular, we redesign three singular omnidirectional devices: the Eaton lens, the generalized Maxwell Fish-Eye, and the invisible sphere. Our designs perfectly reproduce the behaviour of these singular devices, and can be achieved with simple isotropic media of low refractive index contrast.

• 47. Hsieh, K. -H
KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
The manipulation of surface plasmon polaritons and design of luneburg lens based on periodic patch arrays2015Ingår i: 2015 International Workshop on Electromagnetics: Applications and Student Innovation Competition, iWEM 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 1-2Konferensbidrag (Refereegranskat)

We present a surface constitutes arrays of periodic patches, which may serve as the metasurface to synthesize the Luneburg lens. The main purpose is by using different sizes of patches to achieve different refractive index at each stage, and get the proper function of Luneburg lens.

• 48.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Antenna and Sub-Millimeter Waves Section, European Space Agency, Noordwijk, 2200 AG, Netherlands. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Compact Multibeam Fully Metallic Geodesic Luneburg Lens Antenna Based on Non-Euclidean Transformation Optics2018Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 66, nr 12, s. 7383-7388Artikel i tidskrift (Refereegranskat)

Non-Euclidean transformations have been recently proposed to produce a link between 3-D homogeneous surfaces and 2-D dielectric lenses. Therefore, the propagation in a geometrical surface has the same response of an equivalent refractive index distribution. By using this concept, we propose here a fully metallic Luneburg lens where the propagation is only in the air. Two metallic plates, following a curved shape, are employed to support the propagation mimicking the designed curvature. To reduce the height of the required curvature, the surface has been mirrored twice with respect to two z constant planes. The lens is fed by 11 waveguide ports spaced with an angle of 12.5° providing 1-D beam scanning over an angular range of ±62.5°. A prototype is manufactured and measured with a good agreement with the simulated results between 25 and 36 GHz to demonstrate the concept.

• 49.
KTH, Skolan för elektroteknik och datavetenskap (EECS).
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
Higher mode propagation in periodic patch structures with two-dimensional glide symmetries2018Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2018, nr CP741Konferensbidrag (Refereegranskat)

A periodic structure possesses glide symmetry if it is composed of two lattices mirrored and translated half period. We propose here a new king of two-dimensional glide-symmetric structure in microstrip technology. The effect of the glide symmetry on the higher modes is studied in this paper. We compare a glide-symmetric case with only mirrored metasurfaces, and a quarter-period translation case.

• 50.
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Univ Carlos III Madrid, Dept Commun & Signal Theory, Leganes 28911, Spain.. KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elektroteknisk teori och konstruktion.
Ka-Band Fully Metallic TE40 Slot Array Antenna With Glide-Symmetric Gap Waveguide Technology2019Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 67, nr 10, s. 6410-6418Artikel i tidskrift (Refereegranskat)

Gap waveguide has recently been proposed as a low-loss and low-cost technology for millimeter-wave components. The main advantage of the gap waveguide technology is that the microwave components can be manufactured in two metallic pieces that are assembled together without electrical contact. The leakage through a thin air gap between the two pieces is prevented by a 2-D periodic structure offering an electromagnetic bandgap (EBG). This EBG is conventionally implemented with metallic pins. Here, we propose the usage of a holey glide-symmetric EBG structure to design a $4\times 4$ slot array antenna that is fed with a TE40 mode. The TE40 excitation is designed based on a TE10-TE20 mode converter whose performance is initially evaluated by radiation pattern measurements. The final antenna, the $4\times 4$ slot array antenna, was manufactured in aluminum by computer numerical control (CNC) milling. The antenna has a rotationally symmetric radiation pattern that could find application as a reference antenna as well as for 5G point-to-point communications.

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