| 1. |
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| 2. |
- 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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| 3. |
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| 4. |
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| 5. |
- Cheng, Shi, et al.
(författare)
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Compact Reflective Microstrip Phase Shifter for Traveling Wave Antenna Applications
- 2006
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1531-1309 .- 1558-1764. ; 16:7, s. 431-433
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Tidskriftsartikel (refereegranskat)abstract
- A varactor diode based microstrip phase shifter for 5.8 GHz is presented. It is designed for use in microstrip traveling Wave antennas where there is a strict limitation on the available space for the phase shifters. To meet all requirements, a reflective type phase shifter is chosen. Such a phase shifter includes a hybrid coupler. A compact branch line coupler is designed to make the phase shifter fit between the radiating elements in the antenna, while maintaining sufficient electrical performance. Phase shifters are designed with different types of stubs connecting the diodes to ground. A phase tuning range of 621 is measured for a phase shifter with parallel open stubs, and 92 degrees with shorted stubs. Insertion loss is in both cases less than 0.6 dB. A complete five-element array antenna is built and characterized. Measurements show beam scanning angles within 32 degrees from broadside.
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| 7. |
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| 8. |
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| 9. |
- Cheng, Shi, et al.
(författare)
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Foldable and stretchable liquid metal planar inverted cone antenna
- 2009
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 57:12, s. 3765-3771
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Tidskriftsartikel (refereegranskat)abstract
- A mechanically flexible planar inverted cone antenna (PICA) for ultrawideband (UWB) applications is presented. It can be both folded and stretched significantly without permanent damage or loss of electrical functionality. The antenna is manufactured with a process in which conductors are realized by injecting room temperature liquid metal alloy into micro-structured channels in an elastic dielectric material. The elastic dielectric material together with the liquid metal enables bending with a very small radius, twisting, and stretching along any direction. Port impedance and radiation characteristics of the non-stretched and stretched antenna are studied in simulations and experiments. The presented antenna has a return loss better than 10 dB within 3-11 GHz and a radiation efficiency of > 70% over 3-10 GHz, also when stretched. Tests verify that stretching up to 40% is possible with maintained electrical performance. The presented antenna is useful for example for body-worn antennas and in applications in harsh environments where mechanical flexibility helps improve durability.
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| 10. |
- Cheng, Shi, 1980-
(författare)
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Integrated Antenna Solutions for Wireless Sensor and Millimeter-Wave Systems
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents various integrated antenna solutions for different types of systems and applications, e.g. wireless sensors, broadband handsets, advanced base stations, MEMS-based reconfigurable front-ends, automotive anti-collision radars, and large area electronics. For wireless sensor applications, a T-matched dipole is proposed and integrated in an electrically small body-worn sensor node. Measurement techniques are developed to characterize the port impedance and radiation properties. Possibilities and limitations of the planar inverted cone antenna (PICA) for small handsets are studied experimentally. Printed slot-type and folded PICAs are demonstrated for UWB handheld terminals. Both monolithic and hybrid integration are applied for electrically steerable array antennas. Compact phase shifters within a traveling wave array antenna architecture, on single layer substrate, is investigated for the first time. Radio frequency MEMS switches are utilized to improve the performance of reconfigurable antennas at higher frequencies. Using monolithic integration, a 20 GHz switched beam antenna based on MEMS switches is implemented and evaluated. Compared to similar work published previously, complete experimental results are here for the first time reported. Moreover, a hybrid approach is used for a 24 GHz switched beam traveling wave array antenna. A MEMS router is fabricated on silicon substrate for switching two array antennas on a LTCC chip. A concept of nano-wire based substrate integrated waveguides (SIW) is proposed for millimeter-wave applications. Antenna prototypes based on this concept are successfully demonstrated for automotive radar applications. W-band body-worn nonlinear harmonic radar reflectors are proposed as a means to improve automotive radar functionality. Passive, semi-passive and active nonlinear reflectors consisting of array antennas and nonlinear circuitry on flex foils are investigated. A new stretchable RF electronics concept for large area electronics is demonstrated. It incorporates liquid metal into microstructured elastic channels. The prototypes exhibit high stretchability, foldability, and twistability, with maintained electrical properties.
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| 11. |
- 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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| 12. |
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| 13. |
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| 14. |
- Cheng, Shi, et al.
(författare)
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T-matched dipole antenna integrated in electrically small body-worn wireless sensor node
- 2009
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Ingår i: IEE Proceedings - Microwaves Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1350-2417 .- 1359-706X. ; 3:5, s. 774-781
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Tidskriftsartikel (refereegranskat)abstract
- A 2.4 GHz antenna for an electrically small body-worn sensor node is presented. Usually, unbalanced antennas are used in such applications. Implementing a balanced antenna in a small node deployed on the body is problematic from the points of view of both design and characterisation. A solution using a T-matched dipole integrated in the node housing is presented. Techniques for characterisation both in free space and on the body are described. Besides antenna port impedance and radiation efficiency, radiated power and radiation patterns of the active antenna fed by a transceiver in a fully functional sensor node are measured. The benefits and drawbacks of the chosen antenna design and characterisation techniques are discussed.
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| 15. |
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| 18. |
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| 19. |
- Hallbjörner, Paul, 1966
(författare)
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Antennas and Antenna Measurement Techniques for Mobile Communication Terminals
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mobile communication is expanding rapidly, finding new uses and pushing the development of terminals. There are many systems in use today, for example mobile phone systems for voice communication, satellite navigation/positioning systems, and short range data communication. Soon new systems for high speed data communication are expected to emerge, and also systems that use much higher frequencies than today. When it comes to the mobile terminals, some general trends in the development are: shrinking size, more advanced antennas with carefully designed radiation characteristics, larger production volumes, and shorter lead times. This dissertation presents three new antenna types for mobile communication terminals, each studied experimentally. These are the dual feed monopole antenna, a broadband dual RC-loaded loop antenna, and the capacitance-short-load antenna, suitable for different applications. The dual feed monopole antenna is with its two ports suitable for example in satellites where redundancy is required. The RC-loaded loop antenna and the capacitance-short-load antenna are suitable in mobile terminals that are very small compared to the wavelength, e.g. ear plugs and wrist watches. The capacitance-short-load antenna is also highly suitable for electrical tunability over a very wide frequency range. Furthermore, reverberation chamber antenna measurement techniques are studied theoretically and experimentally. The studies include measurement of correlation coefficient between antennas, reflective measurements of free-space reflection coefficient and radiation efficiency, models for mechanical and frequency mode stirring efficiency, a chamber with a Rice distributed signal amplitude, a chamber with an anisotropic signal environment, and a finite probability distribution for random signals with limited power. All these studies serve to expand the usefulness of reverberation chambers as a means for fast, accurate, and cheap antenna characterization, in both product development and production. Finally, information retrieval from phaseless radiation measurements is studied theoretically. Phaseless measurements are common when characterizing the radiation properties of complete mobile terminals, for example in production tests.
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| 20. |
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| 21. |
- Hallbjörner, Paul, et al.
(författare)
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Broadband Space-Time Measurements in Reverberation Chamber Including Comparison With Real Environment
- 2009
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 8, s. 1111-1114
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Tidskriftsartikel (refereegranskat)abstract
- Spatial variations of the broadband time-domain impulse response in a reverberation chamber are studied experimentally. The goal is to introduce the technique as a means for characterizing reverberation chambers and to demonstrate typical results and the information that can be extracted. Similar measurements are performed in a lab room for comparison. The results provide new insights regarding the signal environment inside a reverberation chamber and how it compares to real-life environments. The minimum number of signal paths in the chamber is calculated based on the spatial and temporal resolutions used in the characterization.
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| 22. |
- Hallbjörner, Paul, et al.
(författare)
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Circularly polarized traveling-wave array antenna with novel microstrip patch element
- 2007
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 6, s. 572-574
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Tidskriftsartikel (refereegranskat)abstract
- A traveling-wave microstrip array antenna with circular polarization in presented. It uses a novel circularly polarized dual-feed radiating element. The element is a square microstrip patch with a chamfered corner. It is fed by microstrip lines, so radiating element and feed lines can be realized in a single layer. A five-element array is designed and built. Measured performance is presented.
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| 23. |
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| 24. |
- 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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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- 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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| 30. |
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| 31. |
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| 32. |
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| 33. |
- 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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| 34. |
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| 35. |
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| 36. |
- Hallbjörner, Paul, et al.
(författare)
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Modified planar inverted code antenna for mobile communication handsets
- 2007
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 6, s. 472-475
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Tidskriftsartikel (refereegranskat)abstract
- The planar inverted cone antenna (PICA) is an antenna type that shows remarkably wideband performance. In its basic configuration, it is mounted on an infinite ground plane, and protrudes lambda/4 above it. This letter presents a study of the possibilities of integrating a PICA in a mobile terminal handset by modifying the ground plane and the radiating element. Port impedance and radiation performance are studied in both simulations and measurement.
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