| 1. |
- Ala-Laurinaho, J., et al.
(författare)
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TUMESA - MEMS tuneable metamaterials for smart wireless applications
- 2012
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Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012. - : IEEE. - 9782874870286 ; , s. 95-98
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Konferensbidrag (refereegranskat)abstract
- This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.
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| 2. |
- Chicherin, Dmitry, et al.
(författare)
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All five-loop planar four-point functions of half-BPS operators in N = 4 SYM
- 2018
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 11, s. 1-26
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Tidskriftsartikel (refereegranskat)abstract
- We obtain all planar four-point correlators of half-BPS operators in N = 4 SYM up to five loops. The ansatz for the integrand is fixed partially by imposing lightcone OPE relations between different correlators. We then fix the integrated correlators by comparing their asymptotic expansions with simple data obtained from integrability. We extract OPE coefficients and find a prediction for the triple wrapping correction of the hexagon form factors, which contributes already at the five-loop order.
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| 3. |
- Chicherin, Dmitry, et al.
(författare)
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Analog-type millimeter-wave phase shifters based on MEMS tunable high-impedance surface and dielectric rod waveguide
- 2011
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Ingår i: International Journal of Microwave and Wireless Technologies. - : Cambridge University Press and the European Microwave Association. - 1759-0787. ; 3:5, s. 533-538
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Tidskriftsartikel (refereegranskat)abstract
- Millimeter-wave phase shifters are important components for a wide scope of applications. An analog-type phase shifter for W-band has been designed, analyzed, fabricated, and measured. The phase shifter consists of a reconfigurable high-impedance surface (HIS) controlled by micro-electromechanical system (MEMS) varactors and placed adjacent to a silicon dielectric rod waveguide. The analog-type phase shift in the range of 0–32° is observed at 75 GHz whereas applying bias voltage from 0 to 40 V to the MEMS varactors. The insertion loss of the MEMS tunable HIS is between 1.7 and 5 dB, depending on the frequency.
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| 4. |
- Chicherin, Dmitry, et al.
(författare)
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MEMS based high-impedance surface for millimetre wave dielectric rod waveguide phase shifter
- 2010
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Ingår i: European Microwave Week 2010, EuMW2010. - 9782874870163 ; , s. 950-953
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Konferensbidrag (refereegranskat)abstract
- Analogue type millimetre wave phase shifter based on a dielectric rod waveguide with adjacent MEMS tuneable high-impedance surface is proposed. Applying bias voltage to the MEMS varactors of the high-impedance surface allow controlling its effective impedance and consequently the phase factor of the propagation constant inside the waveguide. The measured phase difference between the phase shifter with adjacent high-impedance surface and phase shifter with low impedance surface is up to 378°. The insertion loss of the high-impedance surface as phase shifting element at 80-90 GHz is 0.5-2.7 dB depending on the distance to the dielectric rod waveguide.
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| 5. |
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| 6. |
- Chicherin, Dmitry, et al.
(författare)
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MEMS tunable metamaterials surfaces and their applications
- 2010
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Ingår i: APMC 2010. - 9781424475902 - 9784902339215 ; , s. 239-242
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Konferensbidrag (refereegranskat)abstract
- Microelectromechanical systems (MEMS) are proposed as a technological solution for fabrication of metamaterials. This enables tunability of metamaterials effective properties and allows using metamaterials in wide range of applications. Low loss of the MEMS devices allows the metamaterials application to be extended to millimeter and submillimeter wave frequencies without compromising on performance. Electronic beam steering by MEMS tunable metamaterials at millimeter wavelength is considered and a prototype of a W band analog tunable phase shifter is demonstrated. The insertion loss of the fabricated MEMS tunable metamaterials surface varies from 0.7 dB to a maximum of 3.5 dB (at a resonance frequency). MEMS varactors have shown reliable and repeatable analog operation over 108 cycles.
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| 7. |
- Chicherin, Dmitry, et al.
(författare)
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Micro-fabricated High-impedance Surface for Millimeter Wave Beam Steering Applications
- 2008
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Ingår i: 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES. - NEW YORK : IEEE. - 9781424421190 ; , s. 574-576
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Konferensbidrag (refereegranskat)abstract
- A multi-layer high-impedance surface has been micro-fabricated and measured in W band. It consists of an array of capacitors placed on a dielectric substrate with a ground plane. Reconfigurability of the effective surface impedance of this structure can be enabled by applying control voltage to the tunable capacitors. Tunable impedance surfaces can be used in phase shifters for a phased array antenna, and directly as a smart beam steering surface.
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| 8. |
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| 9. |
- Du, Zhou, et al.
(författare)
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Reflection phase characterization of the MEMS-based high impedance surface
- 2012
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Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 42nd European Microwave Conference, EuMC 2012<em></em>. - : IEEE. - 9782874870279 ; , s. 617-620
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Konferensbidrag (refereegranskat)abstract
- The reflection properties of the MEMS-based HIS illuminated from oblique angles of incidence have been characterized numerically, and a quasi-optical measurement setup has been built for experimental characterization. The resonance frequency and the relative bandwidth are slightly increasing with the increase of the angle of incidence. The comparison between the simulated and measured results is discussed.
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| 10. |
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