| 1. |
- Arabäck, Niklas, et al.
(författare)
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Serrodyne RF frequency translators for Doppler shift in multipath propagation simulators
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013. ; , s. 985-987
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Konferensbidrag (refereegranskat)abstract
- A frequency translator according to the serrodyne principle, for simulating Doppler shifts within 0-400 Hz, is designed, built, and verified. It is based on commercial analog controlled phase shifters. Serrodyne design aspects as well as control signal hardware and software are described. The design is implemented in a multipath propagation simulator for over-the-air tests of car communication. Measurements on the complete multipath propagation simulator verify the performance of the presented frequency translators.
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| 2. |
- Cheng, Shi, 1980-, et al.
(författare)
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Internal multiple-input, multiple-output antenna arrays for wireless wide area network and wireless local area network operation in seamless full metal cover laptops
- 2014
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Ingår i: IET Microwaves, Antennas & Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 8:2, s. 73-79
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Tidskriftsartikel (refereegranskat)abstract
- A concept for multiple-input, multiple-output antenna arrays, integrated in an ultrathin full metal cover laptop computer, is proposed. The antennas are for octa-band wireless wide area network (WWAN) and triple-band wireless localarea network (WLAN) operation. The proposed solution makes use of the gap between the metallic display lid and keyboard chassis to form notch and slot antenna arrays, thereby removing the need for additional protrusions or openings. Simulated aswell as measured performance is presented. The notch antenna array for WWAN exhibits wide impedance bandwidth, with more than 24 dB isolation from 690 MHz to 3 GHz, and a total efficiency better than −2.5 dB. The slot antenna array forWLAN shows more than 12 dB isolation and a total efficiency of more than −3 dB. Both arrays exhibit a very-low envelope correlation coefficient of less than 0.1 within their respective frequency bands.
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| 3. |
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| 4. |
- Hallbjörner, Paul
(författare)
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Design Rules for Multipath Simulator Antenna Array
- 2010
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Rapport (refereegranskat)abstract
- Multipath simulators are a technique for characterizing wireless terminals, such as for instance mobile phones. A multipath simulator distributes the measurement signal over an array of antennas encircling the test object. When building a multipath simulator, the antenna array should be given an optimal design with respect to the characteristics of the test objects, the parameters to be measured, and the desired measurement accuracy. This report presents mathematical relations which can be used for optimizing the antenna array. The relations are mostly derived theoretically using simple assumptions, and in some instances found from numerical simulations. The report assumes an array with the antennas evenly distributed on a circle with the test object at the center, and a measurement signal power which is uniformly distributed over the array. Considered measured quantities include power, correlation coefficient, and the statistical distribution of amplitudes.
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| 5. |
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| 6. |
- Hallbjörner, Paul, et al.
(författare)
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Improvement in 77 GHz Radar Cross Section of Road Work Jacket and Side Screen by Use of Planar Flexible Retrodirective Reflectors
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. ; 12, s. 1085-1088
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Many road vehicles are today equipped with 77-GHz radar systems for improved road safety. Some objects on the roads, e.g., pedestrians, give a poor reflection of the radar signal. Two applications are studied in this letter: jackets with the reflectors integrated in the lining, and plastic side screens of the type used at road work. A special type of radar reflector is designed, which would be suitable for these applications. The reflector used is a thin and flexible retrodirective microstrip patch antenna array. Panels of suitable size containing a number of these reflectors can be applied to the jacket and the side screen. The improvement in radar cross section is measured. Various design aspects of the chosen reflector, and a comparison to alternative techniques, are discussed.
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| 8. |
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| 9. |
- Hallbjörner, Paul, 1966, et al.
(författare)
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Low-Profile 77-GHz Lens Antenna With Array Feeder
- 2012
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 11, s. 205-207
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Tidskriftsartikel (refereegranskat)abstract
- A 77-GHz lens antenna for automotive radar applications is presented. It consists of a feeder in the formof a 2 x 2 patch array etched from a single layer on a 100-mu m-thick substrate and a commercially available dielectric lens. Compared to previously published lens antennas, the presented design has the advantages of excellent electrical performance and a low profile in combination with a thin lens. Measurements of port impedance match and radiation patterns are presented. Beam tilt by lateral offset of the lens is demonstrated experimentally.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Lindberg, Peter, et al.
(författare)
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Technique of Ground Size Tuning for Isolation between Monopoles in Compact Wireless Terminals
- 2012
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 60:11, s. 5488-5491
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Tidskriftsartikel (refereegranskat)abstract
- Achieving good isolation between two antennas in a wireless terminal is a challenge, especially if it is small compared to the wavelength. This communication presents a technique useful for two monopoles. It is based on placing the monopoles collinearly and tuning the ground plane size to approximately λ/4. Simulations and measurements are presented to illustrate the technique. Different methods of tuning the ground plane size in small terminals are discussed.
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| 18. |
- Nilsson, Mikael, et al.
(författare)
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Multipath propagation simulator for V2X Communication Tests on Cars
- 2013
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Ingår i: 2013 7th European Conference on Antennas and Propagation, EuCAP 2013. - 9788890701832 ; , s. 1342-1346, s. 1342-1346
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Konferensbidrag (refereegranskat)abstract
- Test and evaluation of wireless communication performance with cars can be done in many ways. One approach, for both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) tests, is to use a multipath propagation simulator to achieve realistic signal environments for the different communication systems under test. Multipath propagation simulators have previously been shown to be useful for testing mobile handsets. Specific issues related to tests with cars are the large size of the test object and the disturbances it can cause. In this paper we experimentally study how different design parameters of the multipath propagation simulator affect the received signals. The analysis of the setup as well as the data is performed using the so-called 'Design of Experiments' method.
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| 19. |
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| 20. |
- Sánchez-Heredia, Juan Diego, et al.
(författare)
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Differences in User Influence on MIMO Handset Antenna Performance in Reverberation Chamber
- 2012
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; :2012
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Tidskriftsartikel (refereegranskat)abstract
- User influence on multiple-input multiple-output (MIMO) performance is studied for different dual antenna handsets specially designed to have good and bad MIMO performance. The study reveals that user influence can cause either improvement or degradation for different test objects, including a spread effect over the parameters. Differences in performance between good and bad handsets can be clear when they are measured without user influence, but become small under real person influence. This result illustrates the particular importance of user influence to characterize MIMO handsets.
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| 21. |
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| 23. |
- Valenzuela-Valdés, Juan Fco, et al.
(författare)
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Measuring distributed MIMO system in reverberation chamber
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 12, s. 1586-1589
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Tidskriftsartikel (refereegranskat)abstract
- Reverberation chambers have in recent years been validated as efficient tools for measuring multiple-input-multiple-output (MIMO) systems. Nowadays, cooperative systems are beginning to gain attention as the key to reach high speeds in the wireless environment. These systems often implement the so-called distributed MIMO. A simple method is proposed for characterizing distributed MIMO systems in reverberation chambers. Results for capacity and correlation are shown for three different distributed MIMO systems.
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| 24. |
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| 25. |
- Ödman, Torbjörn, et al.
(författare)
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Experimental study of path loss for UHF band communication near water surface
- 2012
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Ingår i: International Journal on Communications Antenna and Propagation. - 2039-5086. ; 2:3, s. 215-219
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Tidskriftsartikel (refereegranskat)abstract
- The UHF band is often used for communication over water. Presented work quantifies path loss for this scenario. Experimental results are presented within 200 MHz to 1000 MHz, with the antennas positioned up to 2 m above the water surface. Path loss models are created from the measured data.
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| 26. |
- Ödman, Torbjörn, et al.
(författare)
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Vivaldi antenna with low frequency resonance for reduced dimensions
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013. - 9788890701832 ; , s. 2457-2459
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Konferensbidrag (refereegranskat)abstract
- This paper describes a broadband antenna with a design similar to a Vivaldi antenna. The difference is that a resonance is added to get a wider frequency range, which is used to reduce the dimensions of the antenna. The antenna is built and characterized by S11, radiation patterns, and gain.
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