| 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. |
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| 3. |
- Anoshkin, Ilya V., et al.
(författare)
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Freeze-Dried Carbon Nanotube Aerogels for High-Frequency Absorber Applications
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:23, s. 19806-19811
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique for millimeter wave absorber material embedded in a metal waveguide is proposed. The absorber material is a highly porous carbon nanotube (CNT) aerogel prepared by a freeze-drying technique. CNT aerogel structures are shown to be good absorbers with a low reflection coefficient, less than -12 dB at 95 GHz. The reflection coefficient of the novel absorber is 3-4 times lower than that of commercial absorbers with identical geometry. Samples prepared by freeze-drying at -25 degrees C demonstrate resonance behavior, while those prepared at liquid nitrogen temperature (-196 degrees C) exhibit a significant decrease in reflection coefficient, with no resonant behavior. CNT absorbers of identical volume based on wet-phase drying preparation show significantly worse performance than the CNT aerogel absorbers prepared by freeze-drying. Treatment of the freeze-dried CNT aerogel with n- and p-dopants (monoethanolamine and iodine vapors, respectively) shows remarkable improvement in the performance of the waveguide embedded absorbers, reducing the reflection coefficient by 2 dB across the band.
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| 4. |
- Arsanjani, Arash, et al.
(författare)
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A Silicon Micromachined Cascaded Singlet Filtering Antenna at 270 GHz
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper discusses the steps and challenges of implementing a cascaded singlet filtenna using silicon deep reactive ion etching (DRIE) technology. Two fourth-order filtennas with a center frequency of 270~GHz, 14~GHz bandwidth, and a 20~dB inband return loss are fabricated and measured to verify the proposed concept. The measured single-slot and dual-slot filtenna have a peak radiation gain of X~dBi, and Y~dBi at 270~GHz, respectively. Moreover, the challenges and details of silicon micromachining in fabricating these antennas are discussed.Comprehensive details regarding the synthesis procedure, confirmation via simulation, and measurement outcomes are thoroughly explained.
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| 5. |
- Baghchehsaraei, Zargham, 1982-, et al.
(författare)
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Integration of microwave MEMS devices into rectangular waveguide with conductive polymer interposers
- 2013
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:12, s. 125020-
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates a novel method of integrating microwave microelectromechanical systems (MEMS) chips into millimeter-wave rectangular waveguides. The fundamental difficulties of merging micromachined with macromachined microwave components, in particular, surface topography, roughness, mechanical stress points and air gaps interrupting the surface currents, are overcome by a double-side adhesive conductive polymer interposer. This interposer provides a uniform electrical contact, stable mechanical connection and a compliant stress distribution interlayer between the MEMS chip and a waveguide frame. The integration method is successfully implemented both for prototype devices of MEMS-tuneable reflective metamaterial surfaces and for MEMS reconfigurable transmissive surfaces. The measured insertion loss of the novel conductive polymer interface is less than 0.4 dB in the E-band (60-90 GHz), as compared to a conventional assembly with an air gap of 2.5 dB loss. Moreover, both dc biasing lines and mechanical feedthroughs to actuators outside the waveguide are demonstrated in this paper, which is achieved by structuring the polymer sheet xurographically. Finite element method simulations were carried out for analyzing the influence of different parameters on the radio frequency performance.
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| 6. |
- Baghchehsaraei, Zargham, et al.
(författare)
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MEMS 30μm-thick W-band waveguide switch
- 2012
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Ingår i: European Microwave Week 2012. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1055-1058, s. 675-678, s. 1055-1058
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Konferensbidrag (refereegranskat)abstract
- This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.
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| 7. |
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| 8. |
- Baghchehsaraei, Zargham, et al.
(författare)
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MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch
- 2013
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Ingår i: International Journal of Microwave and Wireless Technologies. - 1759-0787. ; 5:3, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents for the first time a novel concept of a microelectromechanical systems (MEMS) waveguide switch based on a reconfigurable surface, whose working principle is to block the wave propagation by short-circuiting the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. The reconfigurable surface is only 30 mu m thick and consists of up to 1260 micro-machined cantilevers and 660 contact points in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. Measurements of fabricated prototypes show that the devices are blocking wave propagation in the OFF-state with over 30 dB isolation for all designs, and allow for transmission of less than 0.65 dB insertion loss for the best design in the ON-state for 60-70 GHz. Furthermore, the paper investigates the integration of such microchips into WR-12 waveguides, which is facilitated by tailor-made waveguide flanges and compliant, conductive-polymer interposer sheets. It is demonstrated by reference measurements where the measured insertion loss of the switches is mainly attributed to the chip-to-waveguide assembly. For the first prototypes of this novel MEMS microwave device concept, the comb-drive actuators did not function properly due to poor fabrication yield. Therefore, for measuring the OFF-state, the devices were fixated mechanically.
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| 9. |
- Baghchehsaraei, Zargham, et al.
(författare)
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Mems-reconfigurable millimeter-wave surfaces for waveguide switches, irises and resonators
- 2014
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Ingår i: The GigaHertz 2014 Symposium.
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Konferensbidrag (refereegranskat)abstract
- This paper presents a concept and prototypes of transmissive millimeter-wave surfaces, which are reconfigurable by integrated micro-electromechanical (MEMS) actuators. The surfaces consist of small vertical elements which can be configured so that they are vertically connected and thus they short-circuit the electrical field lines in the waveguide, which results in total blocking of the wave propagation, or that they are not connected which results in full wave propagation through the surface.
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| 10. |
- Baghchehsaraei, Zargham, et al.
(författare)
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MEMS-reconfigurable wavguide iris for switchable V-band cavity resonators
- 2014
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Ingår i: 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS). - : IEEE. - 9781479935086 ; , s. 206-209
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Konferensbidrag (refereegranskat)abstract
- This paper presents for the first time a novel MEMS-reconfigurable inductive iris based on a 30-μm thick reconfigurable transmissive surface and reports on its application to create a switchable cavity resonator in a WR-12 rectangular waveguide (60-90 GHz). The reconfigurable surface incorporates 252 simultaneously switched contact points for activating (ON state) and deactivating (OFF state) the inductive iris by a 24 μm lateral displacement of two sets of distributed vertical cantilevers. In the ON state, these contact points are short-circuiting the electric field lines of the TE10 waveguide mode on the cross-sectional areas of a symmetric inductive waveguide iris, and are not interfering with the wave propagation in the OFF state. Thus, this novel concept allows for completely switching the inductive iris ON or OFF. The inductive iris has an insertion loss of better than 1.0 dB in the OFF state, of which 0.8 dB is attributed to the measurement setup alone. In the ON state the measured performance of the switchable iris is in good agreement with the simulation results. Furthermore, a novel, switchable cavity resonator was implemented based on such a MEMS-reconfigurable iris, and was characterized to a Q-factor of 186.13 at the resonance frequency of 68.87 GHz with the iris switched ON, and an OFF-state insertion loss of less than 2 dB (including the measurement setup) without any resonance, which is for the first time reported in this paper.
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