| 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. |
- Anoshkin, Ilya, 1980-, et al.
(författare)
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Single walled carbon nanotube quantification method employing the Raman signal intensity
- 2017
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Ingår i: Carbon. - United Kingdom : Elsevier BV. - 0008-6223 .- 1873-3891. ; 116, s. 547-552
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Tidskriftsartikel (refereegranskat)abstract
- A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.
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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. |
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| 5. |
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| 6. |
- 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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| 7. |
- Khanal, S, et al.
(författare)
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Thermal Characterization of THz Schottky Diodes Using Transient Current Measurements
- 2014
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:2, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new method for thermal characterization of THz Schottky diodes. The method is based on the transient current behavior, and it enables the extraction of thermal resistances, thermal time-constants, and peak junction temperatures of THz Schottky diodes. Many typical challenges in thermal characterization of small-area diode devices, particularly those related to self-heating and electrical transients, are either avoided or mitigated. The method is validated with measurements of commercially available single-anode Schottky varactor diodes. A verification routine is performed to ensure the accuracy of the measurement setup, and the characterization results are compared against an in-house measurement-based method and against simulation results of two commercial 3-D thermal simulators. For example, characterization result for the total thermal resistance of a Schottky diode with an anode area of 9 $muhbox{m}^{2}$ is within 10% of the average value of 4020 K/W when using all four approaches. The new method can be used to measure small diode devices with thermal time constants down to about 300 ns with the measurement setup described in the paper.
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| 8. |
- Lioubtchenko, Dmitri V., et al.
(författare)
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Millimetre-wave phase shifter based on dielectric rod waveguide
- 2008
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Ingår i: 38th European Microwave Conference, EuMC 2008; Amsterdam; Netherlands; 27 October 2008 through 31 October 2008. - 9782874870064 ; , s. 1204-1206
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Konferensbidrag (refereegranskat)abstract
- In this work we propose a novel millimetre-wave phase shifter targeted on thin ferroelectric film technology. Architecture of the phase shifter is proposed to use a dielectric rod waveguide with a periodic printed array of electrically small dipoles loaded with a ferroelectric varactor (pin diode, Schottky diode, etc.) with the function of control the phase of the propagating wave. The proposed architecture of the phase shifter is verified by measuring two prototypes, where the tuneable elements (ferroelectric varactor) are replaced by non-tuneable capacitors with 10 fF and 15 fF respectively. The measurements revealed a considerable phase shift and small insertion losses. It is demonstrated that the proposed periodic structure using the dielectric rod waveguide allows to fully realize a potential of known tuneable elements at millimetre-wavelengths.
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| 9. |
- Rivera-Lavado, Alejandro, et al.
(författare)
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Planar Lens–Based Ultra-Wideband Dielectric Rod Waveguide Antenna for Tunable THz and Sub-THz Photomixer Sources
- 2019
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Ingår i: Journal of Infrared, Millimeter and Terahertz Waves. - : Springer. - 1866-6892 .- 1866-6906. ; 40:8, s. 838-855
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Tidskriftsartikel (refereegranskat)abstract
- In this manuscript, the use of dielectric rod waveguide antenna (DRW) with an embedded planar lens is proposed as a highly directional alternative to an electrically large hyper-hemispheric silicon lens for emission at millimeter and sub-millimeter wave frequencies. DRW antennas radiate properly if only the fundamental mode is excited to the structure. Since photomixer-based terahertz sources excite many modes, single-lobe radiation patterns are obtained only for lower frequencies of their potential working band. The use of embedded planar lenses is proposed for rectifying the wavefront phase and suppressing such higher-order modes in DRW, allowing an ultra-wideband operation.
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| 10. |
- Räisänen, Antti, et al.
(författare)
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A single barrier varactor quintupler at 170 GHz
- 1995
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 43:3, s. 685-688
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Tidskriftsartikel (refereegranskat)abstract
- InGaAs-InAlAs single-barrier varactor (SBV) diodes are tested as frequency quintuplers. The diodes were tested in a crossed-waveguide structure and provided output frequencies between 148 and 187 GHz. The highest observed flange-to-flange efficiency was 0.78% at an output frequency of 172 GHz. This is nearly four times greater than the best quintupler efficiency obtained for previous SBV varactors made from the GaAs-AlGaAs materials system.
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