SwePub - sökning: WFRF:(Zetterström Oskar)

Numrering	Referens	Omslagsbild	Hitta
1.	Björkqvist, Oskar, et al. (författare) Additive manufactured dielectric Gutman lens 2019 Ingår i: Electronics Letters. - : Institution of Engineering and Technology. - 0013-5194 .- 1350-911X. ; 55:25, s. 1318-1320 Tidskriftsartikel (refereegranskat)abstract 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.
2.	Algaba-Brazalez, A., et al. (författare) Compact Polarization Transformation in a Geodesic Luneburg Lens Antenna 2021 Ingår i: 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.. ; , s. 1992-1993 Konferensbidrag (refereegranskat)abstract 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°.
3.	Algaba-Brazalez, Astrid, et al. (författare) Crossover level improvement between beams in a geodesic lens antenna based on a generalized Luneburg lens 2022 Ingår i: 2022 16th European Conference on Antennas and Propagation (EuCAP). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract 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.
4.	Ansari, Maral, et al. (författare) A Lightweight Metalized-Insert Luneburg Lens 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract 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.
5.	Börjesson Axén, Jenny, et al. (författare) Short-Term Impact of AC Harmonics on Aging of NiMH Batteries for Grid Storage Applications 2021 Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:5 Tidskriftsartikel (refereegranskat)abstract Batteries in energy storage systems are exposed to electrical noise, such as alternating current (AC) harmonics. While there have been many studies investigating whether Lithium-ion batteries are affected by AC harmonics, such studies on Nickel Metal Hydride (NiMH) batteries are scarce. In this study a 10 Ah, 12 V NiMH battery was tested with three different harmonic current frequency overlays during a single charge/discharge cycle: 50 Hz, 100 Hz, and 1000 Hz. No effect on battery internal temperature or gas pressure was found, indicating that NiMH battery aging is not affected by the tested harmonic AC frequencies. This can reduce the cost of energy storage systems, as no extra filters are needed to safeguard the batteries. Instead, the capacitive properties of the batteries give the possibility to use the battery bank itself as a high pass filter, further reducing system complexity and cost.
6.	Castillo Tapia, Pilar, et al. (författare) Azimuth and Elevation Scanning with Stacked Modulated Geodesic Luneburg Lenses 2022 Ingår i: 2022 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 5-6 Konferensbidrag (refereegranskat)abstract 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.
7.	Castillo Tapia, Pilar, et al. (författare) Two-Dimensional Beam Steering Using a Stacked Modulated Geodesic Luneburg Lens Array Antenna for 5G and Beyond 2023 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:1, s. 487-496 Tidskriftsartikel (refereegranskat)abstract 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.
8.	Chen, Qiao, et al. (författare) Glide-Symmetric Holey Leaky-Wave Antenna With Low Dispersion for 60 GHz Point-to-Point Communications 2020 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 68:3, s. 1925-1936 Tidskriftsartikel (refereegranskat)abstract 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.
9.	Chen, Qiao, et al. (författare) Prism-based Leaky-Lens Antennas at 60 GHz for 5G Point-to-Point Communication Links 2020 Ingår i: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - : IEEE. Konferensbidrag (refereegranskat)abstract 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.
10.	Clendinning, Sarah, et al. (författare) Ray Tracing Model for Non-Rotationally Symmetric Geodesic Lens Antennas with Full Beam Scanning Range in the Azimuthal Plane 2023 Ingår i: The 13th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2023. - : META Conference. ; , s. 1050-1051 Konferensbidrag (refereegranskat)abstract This presentation discusses a ray tracing model developed to determine the radiation pattern of geodesic lens antennas with non-rotationally symmetric footprints, where the geometry of the lens is defined using spline functions. The shape of this footprint and lens height profile can be modified by changing parameters in the defined functions. The code features a significant modification to work previously published by the authors to account for the non-rotationally symmetric design. The model runs significantly faster than commercially available software.
11.	Clendinning, Sarah, et al. (författare) Reducing the Refractive Index Range of GRIN Lenses Through the Integration of a Reflectarray 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract This paper presents a half-lens antenna integrated with a reflectarray. The combination of the half-lens and the reflectarray provides additional design freedom. In this work, this design freedom is used to reduce the refractive index range required to produce a planar wavefront using a half-lens, as compared to the half-Luneburg lens. Specifically, we demonstrate that the properties of a half-Luneburg lens can be mimicked with a lens that has reduced the maximum refractive index by 30% by integrating the reflectarray with the lens.
12.	Clendinning, Sarah, et al. (författare) Tailoring the Performance of Geodesic Lens Antennas By Defining their Footprint 2024 Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract This paper discusses non-rotationally symmetric geodesic lens antennas. By defining the shape of the lens footprint, additional degrees of freedom are introduced into the design process, allowing for further tailoring of the electromagnetic performance of the lens while simultaneously reducing the volume occupied by the lens. An in-house ray-tracing model for geodesic lenses has been modified to analyze this class of lenses. Examples showing the effect of modifying the lens profile are presented, with a more detailed discussion on profile presenting improved side-lobe levels at the extreme ports. The examples presented operate at 30 GHz.
13.	Ebrahimpouri, Mahsa, 1989-, et al. (författare) Experimental Validation of a Bespoke Lens for a Slot log-spiral Feed Annan publikation (populärvet., debatt m.m.)
14.	Ebrahimpouri, Mahsa, et al. (författare) Experimental Validation of a Bespoke Lens for a Slot Log-Spiral Feed 2020 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 19:4, s. 557-560 Tidskriftsartikel (refereegranskat)abstract In this letter, we experimentally validate the concept of bespoke lenses for the specific design of a log-spiral feed. Bespoke lenses are designed using the concept of quasi-conformal transformation optics (QCTO) to enhance the radiation properties for a given feeding. Our experimental results demonstrate that the antenna with its bespoke lens has higher gain, lower cross polarization, lower sidelobes, and lower axial ratio than that with a conventional hyperhemispherical lens.
15.	Eskandari, Hossein, et al. (författare) Design of an Impedance-Matched Horn Antenna with Enhanced Directivity Using Conformal Transformation Optics 2020 Ingår i: 2020 14th European Conference on Antennas and Propagation (EuCAP). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract In this work, conformal transformation optics is employed to enhance the directivity of a horn antenna. The phase error at the horn's aperture is mitigated using a dielectric graded-index lens designed by the conformal transformation. The design not only leads to a negligible phase error at the aperture but also has an excellent impedance match to the vacuum. Simulation results show that for a typical horn antenna with length and aperture width equal to ten wavelengths, our method can enhance the directivity more than 5 dB.
16.	Eskandari, Hossein, et al. (författare) H-plane horn antenna with enhanced directivity using conformal transformation optics 2021 Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1 Tidskriftsartikel (refereegranskat)abstract Conformal transformation optics is employed to enhance an H-plane horn's directivity by designing a graded-index all-dielectric lens. The transformation is applied so that the phase error at the aperture is gradually eliminated inside the lens, leading to a low-profile high-gain lens antenna. The physical space shape is modified such that singular index values are avoided, and the optical path inside the lens is rescaled to eliminate superluminal regions. A prototype of the lens is fabricated using three-dimensional printing. The measurement results show that the realized gain of an H-plane horn antenna can be improved by 1.5-2.4 dB compared to a reference H-plane horn.
17.	Hamarneh, Ramez, et al. (författare) Glide-Symmetric Luneburg Lens Using Substrate-Integrated-Holes for 5G Communications at Ka-Band 2020 Ingår i: Proceedings 14th European Conference on Antennas and Propagation (EuCAP). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract Here, we propose a cost-effective implementation of a planar metasurface Luneburg lens operating at Ka-band. The lens is implemented in a parallel plate structure. The required graded refractive index is realized through spatially varying the dimensions of an array of inclusions placed in both plates of the parallel plate waveguide. More specifically, the inclusions are square holes printed on a substrate which is attached to a ground plane. Each square is surrounded by metallic vias which are connected to the ground plane. The inclusions in both plates are arranged to possess glide symmetry. Waveguide feeds are integrated in the parallel plate waveguide. The lens is terminated with a flare to achieve an efficient radiation to free space.
18.	Liao, Qingbi, et al. (författare) Generalized Ray-tracing Model for Modified Geodesic Luneburg Lens Antennas 2021 Ingår i: 2020 international symposium on antennas and propagation (isap). - : IEEE. ; , s. 193-194 Konferensbidrag (refereegranskat)abstract In this paper, we present an accurate and efficient ray-tracing model for calculating the radiation pattern of rotationally symmetric geodesic lenses. The performance of the ray-tracing model is compared to full-wave simulations, CST and HFSS, through the radiation patterns of a modified geodesic Luneburg lens antenna. The modified geodesic Luneburg lens profile has two parts, one is the original geodesic curve using geometrical optics, and one is a transition for reducing reflections. The radiation pattern from the ray-tracing model has a good agreement with the results from the full-wave simulations. However, the ray-tracing is significantly faster than the full-wave simulators.
19.	Liao, Qingbi, et al. (författare) Generalized Ray-tracing Model for ModifiedGeodesic Luneburg Lens Antennas 2021 Konferensbidrag (refereegranskat)
20.	Lundgren, Johan, et al. (författare) Fully Metallic Dual-Band Linear-to-Circular Polarizer for K/K-a-band 2021 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 20:11, s. 2191-2195 Tidskriftsartikel (refereegranskat)abstract A dual-band polarizer is presented that converts linear polarization into circular polarization with orthogonal handedness in the satcom bands 19.7-20.2 GHz and 29.5-30 GHz. The polarizer consists of three identical cascaded perforated metallic screens, whose perforations are periodically repeated crosses of two sizes. Unlike previously reported dual-band polarizers, our design is fully metallic, which results in low losses and makes it suitable for space applications. A prototype of the polarizer with 20 x 20 unit cells is manufactured, and the measurement results agree well with the simulated results. In the nominal satcom bands, the measured axial ratio and the insertion loss are better than 1.7 and 0.67 dB. In the bands 18.9-20.3 GHz and 29.1-30.1 GHz, the measured axial ratio and insertion loss are below 3 and 1 dB.
21.	Monje Real, Alberto, et al. (författare) Holey Glide-Symmetric Filters for 5G at Millimeter-Wave Frequencies 2020 Ingår i: IEEE Microwave and Wireless Components Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1531-1309 .- 1558-1764. ; 30:1, s. 31-34 Tidskriftsartikel (refereegranskat)abstract A fully metallic glide-symmetric waveguide filter with transmission in Ka -band and attenuation at its second harmonic is proposed. The filter is low-loss and cost-effective for high frequencies, and it can be easily integrated with an antenna. Glide symmetry and the possibility of breaking this symmetry provide an additional degree of freedom for passband and stopband control. A new kind of 2-D glide symmetry, referred to as braided glide symmetry, is presented, showing an increased attenuation per unit cell
22.	Monje Real, Alberto, et al. (författare) Holey Glide-Symmetric Waveguide Filters for 5G Communication Systems at Millimetre Wave Frequencies 2020 Ingår i: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract In this paper, we present a holey, fully-metallic, glide symmetric waveguide filter. This solution is low-loss, cost-effective, robust and suitable for applications at millimetre wave frequencies (e.g. Ka band). We also explore here the possibility to break the glide symmetry as an additional degree of freedom to control the pass and stopbands. Finally, a denser kind of glide symmetry, named braided glide symmetry, is introduced to enhance the attenuation per unit cell.
23.	Petek, Martin, et al. (författare) Fully-Metallic Rinehart-Luneburg Lens at 60 GHz 2020 Ingår i: Proceedings 14th European Conference on Antennas and Propagation (EuCAP). - : Institute of Electrical and Electronics Engineers (IEEE). - 9788831299008 Konferensbidrag (refereegranskat)abstract In this paper, we present the design of a Rinehart-Luneburg lens antenna operating from 56 to 62 GHz. At these high frequencies, dielectric materials introduce high losses, so fully-metallic solutions are typically preferred. The required refractive index of the Luneburg lens is realized by deforming the parallel plate waveguide following the concept of geodesic surfaces. Despite the high frequency, the achieved radiation efficiency is roughly 90%. Thirteen antenna ports are angularly placed along the contour of the lens to enable an electronical beam switching of +/-55 degrees with equally spaced steps and an interleaving dip loss of 6 dB.
24.	Poyanco, Jose-Manuel, et al. (författare) Two-Dimensional Glide-Symmetric Dielectric Structures for Planar Graded-Index Lens Antennas 2021 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 20:11, s. 2171-2175 Tidskriftsartikel (refereegranskat)abstract In this letter, we propose and study a 2-D glide-symmetric dielectric periodic structure. We demonstrate that glide symmetry broadens the bandwidth of operation and achieves lower effective refractive indices when compared to non-glide configurations. These two properties are beneficial for producing graded-index lens antennas. To demonstrate the potential of the proposed unit cell, we designed a Luneburg lens operating in the K- and K-a-bands. The lens was manufactured with conventional additive manufacturing and it has a potential use for future wireless communications given its low-cost and low-profile.
25.	Quevedo-Teruel, Oscar, et al. (författare) Luneburg lenses for the new generation of communication systems 2021 Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021. - : Institute of Electrical and Electronics Engineers Inc.. Konferensbidrag (refereegranskat)abstract Similar to reflectors, lenses can be used to increase the directivity of conventional antennas. The Luneburg lens is a convenient solution that permits multiple/steerable beams with no scan losses. This feature is desirable for antennas in both ground and satellite communications. Depending on the practical needs and physical constraints, Luneburg lenses can be implemented in three- and two-dimensional versions. In the case of three-dimensional lenses, the research has been recently focused in additive manufacturing, which can drastically reduce their cost of implementation. Differently, in two-dimensional versions, the research has been aimed at reducing the use of dielectrics, so losses are reduced, specially in the millimetre wave band. In this contribution, we discuss some relevant implementations of Luneburg lens antennas, and we summarize their use for communications systems.
26.	Saporetti, M. A., et al. (författare) X/Ku/Ka-band high Gain Reflector Antenna Intercomparison Campaign Results 2021 Ingår i: 2021 Antenna Measurement Techniques Association Symposium (AMTA). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract Antenna measurement Intercomparison Campaigns represent a successful activity within the working group on antenna measurement of the European Association on Antennas and Propagation [1] since the group foundation in 2005. These campaigns, constitute an important resource for participating facilities to demonstrate their measurement proficiency, useful internally but also towards obtaining or maintaining official accreditations. In this paper we present the completion of a campaign involving a high gain X/Ku/Ka-band reflector, MVG SR40 fed by an MVG SH4000 Dual Ridge Horn. Preliminary results were shown in [2]. Results from seven facilities are compared through plots of gain/directivity patterns. The data is used to generate reference patterns and establish accurate gain performance data based on the uncertainty estimates provided by each facility. Statistical analysis of the measured data such as Equivalent Noise Level and Birge ratio of each measurement with respect to the established reference will also be shown.
27.	Vidarsson, Freysteinn Vidar, et al. (författare) Achieving Full Azimuth Coverage in a Planar Lens Antenna 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract In this paper we present a lens antenna that can scan in the whole azimuthal plane. This is achieved by using two planar generalized Luneburg lenses that are connected through multiple 3 dB 90 degrees hybrid couplers. The antenna is designed for the 3GPP n260 band operating from 37 to 40 GHz making it suitable for indoor 5G coverage. Simulation results of the antenna are presented to illustrate that it can scan in the full azimuth plane.
28.	Vidarsson, Freysteinn Vidar, et al. (författare) Conformal Parallel Plate Waveguide Polarizer Integrated in a Geodesic Lens Antenna 2022 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 70:11, s. 10327-10337 Tidskriftsartikel (refereegranskat)abstract Here, we propose a low-profile polarizing technique integrated in a parallel plate waveguide (PPW) configuration, compatible with fully metallic geodesic lens antennas. The geodesic shape of the antenna is chosen to resemble the operation of a Luneburg lens. The lens is fed with 11 waveguide ports with 10 degrees separation producing 11 switchable beams in an angular range of +/- 50 degrees. Two metallic polarizing screens are loaded into the aperture of the antenna to rotate the electric field from a vertical linear polarization, which is the polarization of the transverse electromagnetic (TEM) mode supported in the lens, to a +45 degrees linear polarization. Since the polarizing unit cells are integrated into the aperture of the antenna, the final design is compact. In addition, the size of the polarizing unit cells is about 0.55 lambda at the central frequency of operation making the antenna suitable to produce an array formed of stacked lenses. A prototype of the antenna in the Ka-band was manufactured and tested, verifying the performance obtained in simulations.
29.	Vidarsson, Freysteinn Vidar, et al. (författare) Full azimuthal coverage in planar lens antennas 2022 Ingår i: 2022 International Symposium On Antennas And Propagation (ISAP). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 9-10 Konferensbidrag (refereegranskat)abstract This paper describes the design of a generalized Luneburg lens antenna that can scan 360 degrees in azimuth. The full azimuth scanning is achieved by deploying two identically stacked lenses and 3 dB 90 degrees hybrid couplers. The antenna operates in the n260 band, from 37-40 GHz. Simulation results of the integrated antenna system are presented illustrating that the antenna can scan 360 degrees in the azimuth plane.
30.	Wang, Hairu, et al. (författare) Analysis of the Dispersion Diagrams of 3D Cubic Periodic Arrangements of Metallic Spheres 2024 Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract This paper investigates the dispersion properties exhibited by three different three-dimensional (3D) periodic arrangements of metallic spheres with the following underlying lattices: simple cubic (sc), body-centered cubic (bcc) and face-centered cubic (fcc) lattice. Their Brillouin zone (BZ) and the corresponding irreducible BZ are introduced. We then examine the dispersion properties along the edges of their respective irreducible BZs. The findings demonstrate that structures with a non-sc arrangement and higher symmetry can improve design versatility while simultaneously reducing the anisotropy of the structure and broadening the operating frequency range. These advantages are beneficial for the development of 3D graded-index (GRIN) lenses.
31.	Wang, Hairu, et al. (författare) Study and Characterization of 3D Periodic Structures with Higher Symmetries 2023 Ingår i: 2023 International Conference On Electromagnetics In Advanced Applications, Iceaa. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 56-56 Konferensbidrag (refereegranskat)abstract Periodic structures are widely used in the design of microwave devices, such as filters and lenses [1, 2]. By altering the periodic element arrangements or their geometric parameters, the wave propagation properties through the structure can be manipulated to realize different functions. The dispersion diagram, which describes the relationship between wavevector components and frequency, is commonly employed to analyze the behavior of the phase/group velocities in periodic structures. In the engineering community, two-dimensional periodic structures have received significant attention, and structures arranged in rectangular and non-rectangular lattices have been investigated [3]. Additionally, three-dimensional (3D) periodic structures arranged in a simple cubic lattice have been studied, but limited efforts have been invested into other lattice arrangements possible in 3D periodic structures. In this contribution, we investigate the dispersion properties of 3D periodic structures with different lattice arrangements and provide detailed analysis steps. Specifically, the simple cubic, body-centered cubic, and face-centered cubic lattices are taken as examples to demonstrate our proposed analysis. Figure 1 illustrates these lattices and their respective smallest geometrical unit cells [4]. The setting of lattice points represents the underlying geometry of periodic structures. In this study, the connection between the lattices in the real and wavevector space is also shown. The smallest unit cell in the wavevector space that describes the full symmetry of the lattice is known as the Brillouin zone (BZ). By considering the symmetry of the smallest unit cell and the real periodic element, the BZ can be reduced further to the irreducible BZ to simplify the analysis. The dispersion properties of periodic structures can then be analyzed by checking the dispersion diagrams within the irreducible BZ, or even solely along its boundaries. We further compare the dispersion diagrams of the different periodic structures to illustrate some interesting properties of the structures. The extension of this study to more complex lattices is also discussed. The analysis and results shown here facilitate the study of 3D periodic structures and can be used in the antenna design process.
32.	Wang, Hairu, et al. (författare) Three-Dimensional Broadband and Isotropic Double-Mesh Twin-Wire Media for Meta-Lenses 2021 Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 11:15 Tidskriftsartikel (refereegranskat)abstract Lenses are used for multiple applications, including communications, surveillance and security, and medical instruments. In homogeneous lenses, the contour is used to control the electromagnetic propagation. Differently, graded-index lenses make use of inhomogeneous materials, which is an extra degree of freedom. This extra degree of freedom enables the design of devices with a high performance. For instance, rotationally symmetric lenses without spherical aberrations, e.g., the Luneburg lens, can be designed. However, the manufacturing of such lenses is more complex. One possible approach to implement these lenses is using metamaterials, which are able to produce equivalent refractive indices. Here, we propose a new type of three-dimensional metamaterial formed with two independent sets of wires. The double-mesh twin-wire structure permits the propagation of a first mode without cut-off frequency and with low dispersion and high isotropy. These properties are similar to periodic structures with higher symmetries, such as glide symmetry. The variations of the equivalent refractive index are achieved with the dimension of the meandered wires. The potential of this new metamaterial is demonstrated with simulated results of a Luneburg meta-lens.
33.	Yang, Shiyi, et al. (författare) Dispersion Analysis of Metasurfaces With Hexagonal Lattices With Higher Symmetries 2023 Ingår i: IEEE Journal of Microwaves. - : Institute of Electrical and Electronics Engineers (IEEE). - 2692-8388. ; 3:4, s. 1154-1165 Tidskriftsartikel (refereegranskat)abstract This article investigates the dispersion properties of metasurfaces with hexagonal lattices, including potential higher symmetric configurations. We explore the relationships between the periodicity of hexagonal lattices and their dispersion properties, paying special attention to how hexagonal periodic structures can be analyzed with either a hexagonal primitive unit cell or a rectangular supercell. We also study the possibility of introducing higher symmetries into hexagonal periodic structures, including glide symmetry and mirrored half-turn symmetry. To complement and validate the analysis, we designed a graded-index Luneburg lens antenna with a dielectric-filled hexagonal holey structure working in the Ka-band. The antenna generates steerable highly directive beams from 26 GHz to 30 GHz, which corroborates our analysis. Our findings provide valuable insight into the dispersion properties of hexagonal-lattice metasurfaces and demonstrate the feasibility of using such structures in practical applications.
34.	Yang, Shiyi, et al. (författare) Dispersion Diagram Analysis of a Two-Dimensional Hexagonal Periodic Structure 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract This paper focuses on the analysis of the dispersion diagram of a two-dimensional hexagonal periodic structure. The periodic inclusions are placed in a parallel plate waveguide environment and are circular holes located at the vertices of the hexagonal unit cells. The connection between the geometry of the periodic structure and the dispersion diagram is discussed. The wavevector information in the Brillouin zone is illustrated using the reciprocal lattice, from which the shape of the irreducible zone can be derived. The results give insight into the characteristics of the wave propagation characteristic of hexagonal units.
35.	Yang, Shiyi, et al. (författare) Hexagonal higher-symmetric dielectric periodic structures for planar graded-index lenses 2023 Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 123:1 Tidskriftsartikel (refereegranskat)abstract We investigate dispersion properties of a hexagonal dielectric periodic structure that can be used to engineer dielectric graded-index lenses. The connection between the geometry of the hexagonal periodic structure and its symmetries is explained. Furthermore, we demonstrate that a hexagonal structure with increased symmetry is more isotropic than its conventional counterpart. To validate our analysis, we designed, manufactured, and measured a planar Luneburg lens antenna. The antenna has a neat fan-shaped beam from 23 to 31 GHz. The results validate the broadband operation of the periodic structure and could be of interest for the design of cost-effective antennas.
36.	Yang, Shiyi, et al. (författare) Understanding the Dispersion Diagrams of Two-Dimensional Supercells 2022 Ingår i: PROCEEDINGS OF THE 2022 21ST MEDITERRANEAN MICROWAVE SYMPOSIUM (MMS 2022). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 438-441 Konferensbidrag (refereegranskat)abstract This paper discusses the dispersion diagrams of holey periodic metasurfaces, which have been computed by analyzing either the primitive unit cell or a supercell of the structure. Particularly, the connection of the dispersion diagram of the supercell to the standard diagram of the primitive unit cell is investigated. The appearance of additional "anomalous" modes is explained and exemplified in the case of a rectangular supercell composed of two or three square unit cells.
37.	Zeng, Xianliang, et al. (författare) Fully Metallic Glide-Symmetric Leaky-Wave Antenna at K-a-Band With Lens-Augmented Scanning 2022 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 70:8, s. 7158-7163 Tidskriftsartikel (refereegranskat)abstract A fully metallic leaky-wave antenna (LWA) with enhanced scanning rate is presented. The leaky waveguide is implemented in groove gap waveguide technology and is periodically loaded to produce backward radiation. Furthermore, glide-symmetric pins are placed inside the leaky waveguide to increase the dispersion. A parallel-plate waveguide metasurface prism lens is used to disperse the backward radiation and increase the scanning rate of the LWA. The designed antenna can steer the radiation from -26 degrees to 26 degrees from 27 to 35 GHz, and an average total efficiency of 74% is achieved. A prototype of the designed antenna is manufactured, and measurements corroborate the simulated results. The proposed concept is applicable to other frequency-scanning antennas and can be used to increase the scanning rate in radar and imaging systems.
38.	Zetterström, Oskar, et al. (författare) A 28-port MIMO Cube for Micro Base Station Applications 2020 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-926X .- 1558-2221. ; 68:5, s. 3443-3452 Tidskriftsartikel (refereegranskat)abstract A novel multi-band, dual-polarized, 28-port multiple-input multiple-output (MIMO) cube is presented. The cube structure enables dense placement of the antennas, whilst still allowing for low correlation between the individual antenna ports. The total size of the cube is roughly 2×2×7 λ30, where λ0 is the wavelength at the lowest used frequency. The novelty of the design lies in the use of a combination of orthogonally polarized endfire and broadside radiating antenna elements. Full use of all facets of the cube is achieved without the need to sacrifice bottom or top facets for mounting. Therefore, full azimuthal coverage for communication in two orthogonal polarizations is readily achieved. The system operates in both cellular and Wi-Fi 2:4, 5:5 GHz bands, with a targeted \|S11\| below –10 dB. The MIMO performance of the system is evaluated in two environments: the Rich Isotropic Multipath environment and the Random Line-of-Sight environment. These two scenarios represent the edge environments of any real-life propagation scenario in terms of the directional distribution of outgoing or incoming waves at a MIMO transceiver. The intended application of the system is micro base stations and repeaters, with possible extension to massive MIMO.
39.	Zetterström, Oskar, et al. (författare) Additively Manufactured Half-Gutman Lens Antenna for Mobile Satellite Communications 2023 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 22:4, s. 759-763 Tidskriftsartikel (refereegranskat)abstract In this letter, we present an additively manufactured half-Gutman lens antenna operating at 30 GHz. The hemispherical lens allows for a compact beamformer while maintaining the wide scanning capabilities of Gutman lenses. This solution further enables to better integrate the feed system when compared to a more conventional half-Luneburg lens antenna design as the focal arc is moved inside the lens. The graded-index of the lens is implemented with a periodic structure arranged in a body-centred cubic (BCC) lattice. We demonstrate that the BCC structure provides attractive properties for the design of inhomogeneous dielectric lenses. Importantly, the BCC structure can be used to alleviate the manufacturing constrains compared to conventional periodic structures. The lens is fed by a dielectric-loaded square waveguide. The proposed antenna produces a directive beam with a simulated and measured peak gain of 26.2 and 25.3 dBi. The antenna can steer its beam in a 50 degrees range in elevation with measured scan loss and sidelobe levels below1 dB and-10 dB, which agree with the simulated values. The measured cross polarization discrimination is better than 20 dB. The proposed antenna is intended for the ground segment of the emerging low-Earth-orbit satellite communication applications.
40.	Zetterström, Oskar (författare) Antennas Based on Rotationally Symmetric Lenses for High-Frequency Wireless Applications 2024 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract This thesis investigates lens antennas for future wireless applications. The aim is to provide robust and cost-effective antenna solutions with wide-angle beam steering capabilities. The wide-angle beam steering is obtained using rotationally symmetric inhomogeneous lenses, such as the Luneburg lens. The derivation of the inhomogeneous refractive index using geometrical optics is outlined. Parallel plate waveguide (PPW) lens antennas and volumetric lens antennas are investigated. The studied PPW lens antennas are designed to be robust to manufacturing and assembly errors while enabling a high radiation efficiency and wide-angle steering of a fan-shaped beam. The refractive index distribution is mimicked using quasi-periodic structures or by shaping the PPW. Specifically, two robust and cost-effective glide-symmetric quasi-periodic structures are proposed. First, glide-symmetric substrate-integrated holes (SIHs) are proposed, since they enable a larger PPW spacing compared to previously reported fully-metallic designs. This large PPW spacing translates into a robust antenna solution, and the SIH structure can be cost-effectively manufactured. The presence of the dielectric introduces losses, but it is shown that these added losses are sufficiently low for many applications at Ka-band. Secondly, a glide-symmetric perforated dielectric slab is proposed to enable an even larger PPW spacing. The slab is produced using additive manufacturing and it is shown that by arranging the perforations glide-symmetrically, a wider range of effective refractive indices can be accurately realized. Again, it is shown that the added losses due to the dielectric are sufficiently low for practical applications at Ka-band. Fully-metallic (and therefore highly efficient) PPW lens antennas can be based on geodesic lenses. These lenses do not require the realization of any small features and can therefore be robust. A geodesic lens antenna demonstrator at V-band is presented, and techniques of reducing the sensitivity to manufacturing errors are proposed. These techniques are later used in the design of a geodesic lens antenna with reduced gain variation within the beam steering range compared to the reference works. This geodesic lens is based on the generalized Luneburg lens. Providing a low gain variation in the steering range ensures a good quality of service to all end users. Additive manufacturing provides attractive opportunities for the realization of volumetric inhomogeneous lens antennas capable of producing directive pencil beams that can be steered in a wide angular range. However, the effective refractive index range of quasi-periodic dielectric structures is often limited by the smallest realizable geometrical detail, and the reported volumetric inhomogeneous lenses are often truncated, which impacts their focusing properties. In this thesis, the impact of the lattice arrangements is discussed and it is demonstrated that by using highly symmetric lattice arrangements, the realizable effective refractive index range can be increased. Furthermore, a new lens, accounting for the manufacturing constraints, is also proposed. This lens operates similarly to the Luneburg lens, but it has a refractive index distribution that can be tuned to alleviate the manufacturing.
41.	Zetterström, Oskar, et al. (författare) Collimating Truncated Virtual Image Lens 2024 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 72:5, s. 3928-3937 Tidskriftsartikel (refereegranskat)abstract The Luneburg lens is of significant interest for microwave and optical devices due to its wide-angle focusing properties. However, the inhomogeneous refractive index of the lens is restrictive and can be difficult to realize, especially at high frequency (typically millimeter-waves and above). Here, we present an inhomogeneous lens referred to as the collimating truncated virtual image lens, which is derived as a combination of the recently proposed virtual image lens and a conventional extended hemispherical lens. We investigate the operation of the proposed lens and we demonstrate that it provides similar focusing properties as the Luneburg lens, but with a flexible refractive index profile. This flexibility can be used to alleviate the strict manufacturing constraints typically associated with the Luneburg lens. We validate the properties of the proposed lens with a demonstrator at millimeter-wave frequencies showing that an antenna based on the proposed lens can obtain similar directivity and sidelobe levels to those obtained in an ideal Luneburg lens antenna, while the proposed lens is easier to realize. The collimating truncated virtual image lens is attractive for instruments and antennas at high frequency.
42.	Zetterström, Oskar, et al. (författare) Compact Half-Luneburg Lens Antenna Based on a Glide-Symmetric Dielectric Structure 2022 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 21:11, s. 2283-2287 Tidskriftsartikel (refereegranskat)abstract In this letter, we present a planar half-Luneburg lens antenna based on a glide-symmetric dielectric structure. The proposed half-Luneburg lens antenna provides a compact alternative to planar beamformers such as conventional Luneburg and Rotman lenses, as well as pillbox antennas. Importantly, we demonstrate that the peak gain of the half-Luneburg lens antenna is less than 1 dB lower than the peak gain of a conventional Luneburg lens antenna, despite being almost half the size. The proposed antenna can steer its beam in a 50 degrees range with scan losses lower than 2 dB and side lobe levels below -10 dB. The proposed design is validated experimentally with a robust and cost-effective implementation using additive manufacturing.
43.	Zetterström, Oskar, et al. (författare) Comparison and Limitations of Measurement Techniques forBody Absorption in mm-Waves : Project report 2022 Rapport (övrigt vetenskapligt/konstnärligt)abstract Wireless communications are rapidly evolving. In particular, users are demanding new services in the present networks that require higher data transfer. The new generation of mobile communications, 5G, started to be deployed at the end of 2019. However, this first implementation of 5G will only cover part of the needs of users. Further research to increase the rates of wireless communications is currently needed to cover the expectations in the near future. Since most of the low frequency spectrum is already crowded, the only possibility is increasing the operational frequency to the millimetre-wave (mm-wave) regime where narrow bands permit largerdata transfer and short delays. As all the devices radiating radio frequency electromagnetic fields (EMFs), the mm-wave devices need to be assessed to show the compliance with EMF exposure limits specified by standards and regulations. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) is an international association whose EMF guidelines from 1998 have been adopted in standards and regulations in many countries worldwide. On March 11, 2020, ICNIRP released new guidelines for exposure to RF EMF in the frequency range 100 kHz to 300 GHz. One difference between the new and the previous guidelines from 1998 is the basic restrictions on the whole-body exposure. The whole-body exposure basic restriction in ICNIRP (1998) was set in terms of the quantity “SAR” (Specific Absorption Rate). This is also the case for ICNIRP (2020). However, whereas this restriction only applied upto 10 GHz in ICNIRP (1998), it is applicable across the entire 100 kHz to 300 GHz range in ICNIRP (2020). This will ensure that exposures from new technologies donot lead to an excessive temperature rise deep in the body. The whole-body averaged SAR is defined as the total absorbed power divided by the whole-body mass. For frequencies below 10 GHz, the whole-body SAR measurement procedure explained in EMF exposure assessment standards requires measuring the field strength inside a tissue-equivalent liquid (a human phantom) to obtainthe total absorbed power. However, this method is very difficult to use for high frequency EMF waves (such as mm-waves) since the penetration depth is superficial. Within this project, we study alternatives for measuring the whole-body averaged SAR at mm-waves. In this report, we outline various methods for estimating the SAR reported in the literature. From this literature review, we identify promising techniques. We provide a critical assessment of two of the promising techniquesusing numerical simulations.
44.	Zetterström, Oskar, et al. (författare) Compressed Lenses via Transformation Optics for Mobile Satellite Communications 2020 Ingår i: Proceedings 14th European Conference on Antennas and Propagation (EuCAP). - : Institute of Electrical and Electronics Engineers (IEEE). Konferensbidrag (refereegranskat)abstract In this paper, the design of a volumetric Luneburg lens antenna is described. Transformation optics is used to compress the height of the lens. A moderate compression of 30% is applied to facilitate an all-dielectric realization. A gain of almost 20 dBi is obtained in simulations with a lens diameter of 4 free space wavelengths before compression. The gain of the compressed lens is 1 dB lower and 2 dB higher, compared to conventional Luneburg lenses with the same diameter and height, respectively. The antenna is intended for satellite communications on -the -move through low Earth orbit constellations.
45.	Zetterström, Oskar, et al. (författare) Discussion on Forward and Backward Modes in Periodic Bounded Structures 2023 Ingår i: 2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP. - : IEEE. Konferensbidrag (refereegranskat)abstract We discuss forward and backward modes in one-dimensional (1-D) periodic bounded structures. First, it is shown that the conventional definition of the phase speed can incorrectly identify the forward/backward nature of modes. Therefore, we propose an alternative definition of the phase speed for modes in bounded periodic structures and demonstrate that this definition correctly identifies the nature of modes in a 1-D periodic corrugated parallel plate waveguide. The proposed phase speed is analyzed through simulations with commercial software and a circuit model.
46.	Zetterström, Oskar, et al. (författare) Dispersion Analysis of Periodically Loaded Transmission Lines with Twist Symmetry Using the Mode-Matching Technique 2020 Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 10:17 Tidskriftsartikel (refereegranskat)abstract A mode-matching formulation is presented and used to analyze the dispersion properties of twist-symmetric transmission lines. The structures are coaxial lines periodically loaded with infinitely thin screens, which are rotated with respect to each other to possess twist symmetry. The results obtained using the proposed formulation are in good agreement with those of commercial simulators. Furthermore, using the presented mode-matching formulation, it is demonstrated that the propagation characteristics in the twist-symmetric structures are linked to the scattering and coupling of the higher order modes. The physical insight offered by this analysis is valuable for the design of various electromagnetic devices, such as filters, antennas, and phase-shifters.
47.	Zetterström, Oskar, et al. (författare) Experimental Validation of a Metasurface Luneburg Lens Antenna Implemented With Glide-Symmetric Substrate-Integrated Holes 2021 Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 20:5, s. 698-702 Tidskriftsartikel (refereegranskat)abstract In this letter, we present the experimental validation of a K-a-band Luneburg lens antenna based on a novel cost-effective metasurface. The metasurface is composed of a parallel plate waveguide (PPW) loaded with quasi-periodic inclusions in both conductors. The inclusions are square holes printed on a substrate, with vias placed around the holes. The vias connect the printed layer of the substrate to the ground. This configuration is named substrate-integrated hole (SIH). It is demonstrated that the SIH metasurface can obtain a higher effective refractive index, compared to the conventional holey metasurface. To further increase the effective refractive index, the SIHs in the two conductors of the PPW are glide-symmetrically arranged. The refractive index distribution of the Luneburg lens is realized by locally tuning the dimensions of the SIHs. The lens is fed with 11 waveguide feeds with an angular separation of 10 degrees. Thus, the antenna can steer its radiation in a 100 degrees angular range. A flare is integrated with the PPW to match the antenna to the free-space impedance. Since the wave propagates mainly in the PPW air gap, the dielectric losses are low. The measured radiation efficiency of the antenna is roughly 80%.
48.	Zetterström, Oskar, et al. (författare) Glide-Symmetric Luneburg Lens Based on Substrate-Integrated-Holes 2021 Ingår i: The 11th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2021. - : META Conference. ; , s. 609-610 Konferensbidrag (refereegranskat)abstract We propose a novel parallel plate waveguide (PPW) metasurface. The PPW is periodically loaded with glidesymmetrically arranged dielectric-filled cavities in both conductors. By filling the cavities with dielectric, the equivalent refractive index increases. To facilitate the manufacturing using conventional methods, the walls of the cavities are implemented with metallic vias and the proposed structure is used to design a Luneburg lens. Compared to previous works on holey metasurfaces, the designed lens is cheaper and more resilient to manufacturing errors.
49.	Zetterström, Oskar, et al. (författare) Higher Symmetries in Hexagonal Periodic Structures 2024 Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788831299091 Konferensbidrag (refereegranskat)abstract We study higher-symmetric periodic structures with hexagonal lattice arrangement. We define three ways to synthesize a glide symmetry in a hexagonal lattice. If the periodic motifs have sufficient symmetry, the three resulting structures are related through a rotation. Furthermore, we define two ways of synthesizing a mirrored half-turn symmetry in a hexagonal lattice. Again, if the periodic motifs have sufficient symmetry, the two resulting structures are related through a rotation. We analyze a structure with mirrored half-turn symmetry and compare its response to that of a periodic structure with conventional hexagonal symmetry. The mirrored half-turn-symmetric structure provides a higher effective refractive index for the same geometrical dimensional. As a result, the higher-symmetric structure is useful for devices in future wireless applications.
50.	Zetterström, Oskar, et al. (författare) Metasurface Luneburg Lens Antenna Implemented with Substrate-Integrated-Holes at Ka-Band 2021 Ingår i: 2021 15Th European Conference On Antennas And Propagation (EUCAP). - : IEEE. Konferensbidrag (refereegranskat)abstract In this work, we study the substrate-integrated-holes (SIHs) metasurface. This metasurface consists of dielectric-filled cavities in the two conductors of a parallel plate waveguide (PPW). The accurate control of the effective refractive index in the SIH structure is demonstrated. Additionally, we design a metasurface Luneburg lens operating at 28 GHz based on the studied structure. The lens is fed with 11 waveguides with an angular spacing of 10 degrees, and thus, 100 degrees beam steering is obtained. A flare is used to match PPW to free-space. Since the wave propagates mainly in the air in the studied metasurface, low losses are obtained in the designed lens.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "WFRF:(Zetterström Oskar) "

Avgränsa träffmängd

År