| 1. |
- A. Mouris, Boules, et al.
(författare)
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A Dual-Polarized Multi-Antenna Structure for Simultaneous Transmission of Wireless Information and Power
- 2019
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Ingår i: 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, APSURSI 2019 - Proceedings. - : IEEE. ; , s. 1805-1806
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Konferensbidrag (refereegranskat)abstract
- In this paper, a dual-polarized multi-antenna structure is designed at 2.45 GHz with the goal of allowing simultaneous transmission of wireless information and power. Differential feeding was used to minimize the mutual coupling due to radiation leakage in addition to a mushroom-type EBG structure for suppressing the surface waves. Simulation results for the proposed structure show a mutual coupling level lower than -40 dB between the information transmitting antenna and the power transmitting antennas for both polarizations. The isolation level between the antennas is improved by at least 22 dB and 14 dB for the E-plane and H-plane coupling, respectively.
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| 2. |
- Bantavis, P. I., et al.
(författare)
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A Cost-Effective Wideband Switched Beam Antenna System for a Small Cell Base Station
- 2018
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-926X .- 1558-2221. ; 66:12, s. 6851-6861
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Tidskriftsartikel (refereegranskat)abstract
- A wideband switched beam antenna array system operating from 2 to 5 GHz is presented. It is comprised of a 4 × 1 Vivaldi antenna elements and a 4 × 4 Butler matrix beamformer driven by a digitally controlled double-pole four-throw RF switch. The Butler matrix is implemented on a multilayer structure, using 90° hybrid couplers and 45° phase shifters. For the design of the coupler and phase shifter, we propose a unified methodology applied, but not limited, to elliptically shaped geometries. The multilayer realization enables us to avoid microstrip crossing and supports wideband operation of the beamforming network. To realize the Butler matrix, we introduce a step-by-step and stage-by-stage design methodology that enables accurate balance of the output weights at the antenna ports to achieve a stable beamforming performance. In this paper, we use a Vivaldi antenna element in a linear four-element array, since such element supports wideband and wide-scan angle operation. A soft condition in the form of corrugations is implemented around the periphery of the array, in order to reduce the edge effects. This technique improved the gain, the sidelobes, and helped to obtain back radiation suppression. Finally, impedance loading was also utilized in the two edge elements of the array to improve the active impedance. The proposed system of the Butler matrix in conjunction with the constructed array can be utilized as a common RF front end in a wideband air interface for a small cell 5G application and beyond as it is capable to simultaneously cover all the commercial bands from 2 to 5 GHz.
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| 3. |
- Bantavis, P. I., et al.
(författare)
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A Wideband Switched Beam Antenna System for 5G Femtocell Applications
- 2017
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Ingår i: 2017 IEEE Antennas and Propagation Society International Symposium, Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538632840 ; , s. 929-930
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Konferensbidrag (refereegranskat)abstract
- This work introduces a wideband switched beam system for femtocell 5G base stations. The system consists of a 4 x 1 Vivaldi linear array and a 4 x 4 Butler matrix able to operate from 1.9-5.1 GHz. A soft surface is introduced along the outer edges of the vivaldi elements of the array for side lobes and back radiation suppression.
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| 4. |
- Björkqvist, Oskar, et al.
(författare)
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A Novel Efficient Multiple Input Single Output RF Energy Harvesting Rectification Scheme
- 2017
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Ingår i: 2017 IEEE Antennas and Propagation Society International Symposium, Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538632840 ; , s. 1605-1606
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Konferensbidrag (refereegranskat)abstract
- In this work an implementation of an ambient radio frequency harvesting system utilizing multiple input single output approach is demonstrated. Measurements of typical ambient radiation have been conducted with respect to power levels and frequency to determine which communication signals are suitable for harvesting. The measurement campaign showed that the WiFi frequency band at 2.45 GHz is a good candidate for indoors applications. A Greinacher voltage doubler is used for the rectification. A multiple input single output - MISO scalable scheme approach is implemented that is able to provide a DC differential output voltage. Simulated and experimental results proved the MISO rectenna to be an efficient scheme for RF harvesting.
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| 5. |
- Björkqvist, Oskar, et al.
(författare)
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Wireless Sensor Network Utilizing Radio-Frequency Energy Harvesting for Smart Building Applications
- 2018
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Ingår i: IEEE Antennas & Propagation Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1045-9243 .- 1558-4143. ; 60:5, s. 124-136
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Dahlberg, Oskar, et al.
(författare)
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A Novel 32 Port Cube MIMO Combining Broadside and Endfire Radiation Patterns for Full Azimuthal Coverage - A Modular Unit Approach for a Massive MIMO System
- 2017
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Ingår i: 2017 IEEE Antennas and Propagation Society International Symposium, Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538632840 ; , s. 1641-1642
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Konferensbidrag (refereegranskat)abstract
- In this paper we propose a novel 32 antenna port multiple-input-multiple-output (MIMO)-cube. The total volume of the cube is 320 x 320 x 120 mm(3) . On two faces, endfire radiating linear tapered slot antennas (LTSAs) are placed and on the remaining sides, a mix of both LTSAs and broadside patch antennas are placed. In total 16 LTSAs and 8 dual polarized patches are used. The LTSA is designed to operate at the GSM and 3G bands, from 1.7 to 2.3 GHz. A corrugation pattern is introduced along the edges of the LTSAs covering one face to increase directivity and decrease sidelobes. The LTSAs are placed in two different orientations in order to receive two polarisations. The patch antenna is dual band and dual polarized. It operates in the frequency bands 2.4-2.5 and 5.45-5.6 GHz where Wi-Fi communication is made. The spatial placement, with antennas on all sides of the cuboid, ensures full azimuthal coverage despite the high directivity of the antennas. Using different antennas on different faces of the cube further optimizes the volume efficiency of the cube for azimuthal coverage.
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| 7. |
- Fakoukakis, F. E., et al.
(författare)
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Ultra-Wideband butler matrix Fed MIMO antennas
- 2015
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Konferensbidrag (refereegranskat)abstract
- This work elaborates on the design of an Ultra-Wideband (UWB) Butler matrix fed antenna array, implementing a Multiple Input-Multiple Output (MIMO) configuration. The system aims at applications in future Long Term Evolution (LTE) and multifunctional Radar systems. Specifically, based on the results of our previous works, the research is extended towards the implementation of a MIMO beamforming scheme. Different beamforming scenarios are applied, in order to maximize system performance and minimize noise and interference. A comprehensive analysis and design procedure is presented, along with system simulation results.
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| 8. |
- Jonsson, B. Lars G., et al.
(författare)
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Array Antenna Limitations
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 12, s. 1539-1542
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Tidskriftsartikel (refereegranskat)abstract
- This letter defines a physical-bound-based array figure of merit for both single and multiband array antennas. It provides a measure to compare their performance with respect to return loss, bandwidth(s), thickness of the array over the ground plane, and scan range. The result is based on a sum-rule result of Rozanov-type for linear polarization. For single-band antennas, it extends an existing limit for a given fixed scan-angle to include the whole scan range of the array, as well as the unit-cell structure in the bound. The letter ends with an investigation of the array figure of merit for some wideband and/or wide-scan antennas with linear polarization. We find arrays with a figure of merit >0.6 that empirically defines high-performance antennas with respect to this measure.
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| 9. |
- Jonsson, B. Lars G., et al.
(författare)
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On methods to estimate bandwidth performance for array antennas with ground plane
- 2014
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Ingår i: 2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014. - 9781467352253
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Konferensbidrag (refereegranskat)abstract
- Array antenna impedance bandwidth performance is a critical factor for antenna design, in particular for arrays in radar application and more recently for array antennas in communication systems. A priori methods to quantify bandwidth include stored energy-based estimates through the quality factor antenna Q, and sum-rule based estimates based on the antenna as a scattering object. A recently introduced, array figure of merit, uses a square window or walltype estimate on the return-loss to obtain bounds in terms of return-loss level, bandwidth, scan-range and unit-cell specific geometrical and material information, it is based on a fundamental physics result, linking bandwidth to essentially the thickness of the array. An alternative approach is based on the Bode-Fano theory, resulting in bandwidth measures in terms of one or several quality factors. Both methods apply both to single and multi-band array antennas. Here we present these methods and make a comparison between the two approaches.
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| 10. |
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