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- 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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| 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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| 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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