| 1. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
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A novel catadioptric dielectric lens for microwave and terahertz applications
- 2008
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Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 50:2, s. 416-419
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Tidskriftsartikel (refereegranskat)abstract
- A novel dielectric catadioptric lens, suitable for near-field sensing and imaging, is presented. The focusing property and the far-field pattern of the lens are investigated using a 3D full-wave electromagnetic solver. Furthermore, the proposed catadioptric lens has been designed and fabricated from Delrin. Simulations and measurements of the far-field at 5 GHz and return loss versus frequency using a Bow-tie slot feeding antenna are presented.
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| 2. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
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Catadioptric Microlenses for Submillimeter and Terahertz Applications
- 2006
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Ingår i: 17th International Symposium on Space THz Technology – ISSTT 2006.
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Konferensbidrag (refereegranskat)abstract
- Existing dielectric lens geometries are optimized for remote sensing applications in order to produce a predetermined Gaussian beam in the far field that is matched to a radioastronomic setup. In this work, an optics suitable forobject investigation in a point-to-point transmission setup is presented. Here it is required to create a focus point outside the lens with as low radiation leakage as possible. For this, a catadioptric dielectric lens is proposed. This paper presents the theoretical performance of the focusing property of catadioptric lens investigated at 50 GHz and 228 GHz having er = 11.7. 3D simulation results of the catadioptric lens also show a focus point. Imaging property of catadioptric and extended hemispherical lenses are presented and compared at 50GHz. A Transient analysis of the lens is also presented.
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| 3. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
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VO2 TES as Room Temperature THz Detectors
- 2006
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Ingår i: 17th International Symposium on Space THz Technology – ISSTT 2006.
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Konferensbidrag (refereegranskat)abstract
- Abstract VOx materials hold very high potential to be used as room temperature bolometer. A brief review on room temperature bolometers and VOx characteristics is presented. The hysteretic metal-insulator transition behavior of a VOxmicrobolometer has been investigated. An algebraic hysteresis model has been used to model the resistance-temperature characteristic of the bolometer. The magnetic limiting loop proximity (L2 P) hysteresis theory is modified to represent the VOx major and minor hysteresis loops. The responsivity of the bolometer is also calculated. Loop accommodation process is explained. Nonsymmetrical hysteretic behavior has also been discussed.
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| 4. |
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| 5. |
- Baubert, Jean, 1976, et al.
(författare)
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IF Gain Bandwidth of membrane-based NbN Hot Electron Bolometers for SHAHIRA
- 2005
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Ingår i: IEEE Applied Superconductivity. ; 15:2, s. 505-510
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Tidskriftsartikel (refereegranskat)abstract
- SHAHIRA (Submm Heterodyne Array for HIghspeedRadio Astronomy) is a project supported by the EuropeanSpace Agency (ESA) and is designed to fly on the SOFIA observatory.A quasi-optic design has been chosen for 2.5/2.7 THz and4.7 THz, for hydroxyde radical OH, deuterated hydrogen HD andneutral atomic oxygen OI lines observations. Hot electron bolometers(HEBs) have been processed on 1 um thick SiO2 Si3N4stress-less membranes. In this paper we analyse the intermediatefrequency (IF) gain bandwidth from the theoretical point of view,and compare it to measurements.
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| 8. |
- de Graauw, Th., et al.
(författare)
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The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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| 9. |
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International Symposium on Space Terahertz Technology
- 2006
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- The 16th International Symposium on Space Terahertz Technology was held at Chalmers, Göteborg, Sweden on May 2-4, 2005. This was the fi rst time the ISSTT meeting was held outside the US. More than 150 delegates from Europe, US and Asia attended and 147 scientifi c papers were presented. The meeting was organised by research groups at the microwave electronics laboratory, MC2, and GARD, Onsala space observatory. The programme was divided into 11 oral sessions with 63 papers (5 invited) and one poster session with 83 papers. Latest result on terahertz technologies for space applications were presented such as sensitive superconducting electronics (HEB/SIS), detectors, sources and systems. New applications of terahertz technology, e.g. for biotechnology, were also presented by Peter Siegel, Caltech (invited talk). Furthermore, we offered lab tours through MC2, conference dinner at Elfsborgs Fästning and fi nally a trip to Onsala space observatory. The symposium was sponsored by the Swedish Research Council (VR), IEEE Sweden Section, Swedish Space Corporation, Ericsson AB, COMSOL AB and our exhibitors: Omnisys Instruments AB, SAAB Ericsson Space AB, and European Southern Observatory (ESO). I would like to thank these organisations for their support. I would also like to thank everyone who helped to make the Symposium a success: international steering committee for advice and for reviewing abstracts; local organising committee; Eva Hellberg and Peter Jönsson for WEB support; Monica Hansen-Torvaldsson, Catharina Forssén, and Ingrid Collin for help with registrations and payments; Chalmers president Jan-Eric Sundgren and Erik Kollberg for opening the meeting; staff at Chalmers Conference Center; the session chairmen; and everyone who attended or contributed a presentation. Also an additional thanks to Mattias Ingvarson for putting this proceeding together.
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| 13. |
- Merkel, Harald Franz Arno, 1966, et al.
(författare)
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Quantum Noise in Resistive Mixers
- 2006
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Ingår i: 17th International Symposium on Space Terahertz Technology ISSTT 2006.
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Konferensbidrag (refereegranskat)abstract
- Derivation of the quantum noise of a mixer using second order quantization methods.
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| 14. |
- Merkel, Harald Franz Arno, 1966, et al.
(författare)
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Twodimensionally distributed Model for HEB based on Random Phase Transitions
- 2006
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Ingår i: 17th International Symposium on Space Terahertz Technology ISSTT 2006.
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Konferensbidrag (refereegranskat)abstract
- According to AFM measurements, ultrathin NbN films are not smooth but exhibit a more or less random distribution of microcrystallites. This gives rise to a superconducting to normal conducting phase transition that follows a first order percolation phase transition. Such a phase transition is easily described by a single critical exponent justifying the assumption of a simple, local R(T) curve used in all distributed HEB models.
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