Molecular Spectroscopy With a Compact 557-GHz Heterodyne Receiver
P.F.-X. Neumaier1, H. Richter1, J. Stake2, H. Zhao2, A.-Y. Tang2, V. Drakinskiy2, P. Sobis3, A. Emrich3, A. Hülsmann4, T.K. Johansen5, T. Bryllert6, J. Hanning2, V. Krozer7,8, and H.-W. Hübers1,9
Published in:
IEEE Trans. Terahertz Sci. Technol., vol. 4, no. 4, pp. 469-478 (2014).
Abstract:
We report on a heterodyne terahertz spectrometer based on a fully integrated 557-GHz receiver and a digital fast Fourier transform spectrometer. The receiver consists of a chain of multipliers and power amplifiers, followed by a heterostructure barrier varactor tripler that subharmonically pumps a membrane GaAs Schottky diode mixer. All sub-components are newly developed and optimized with regard to the overall receiver performance such as noise temperature, power consumption, weight and physical size. The receiver works at room temperature, has a double sideband noise temperature as low as 2000 K at a maximum power consumption of 4.5 W with an Allan time of 10 s and a sideband gain ratio of 0.52. The performance of the spectrometer is demonstrated by absorption spectroscopy of H2O and CH3OH with an instantaneous bandwidth of 1.5 GHz and a resolution of 183 kHz. Several pressure broadening parameters of methanol absorption lines were determined, that agree with other published data. Using the experimentally determined molecular parameters the CH3OH absorption spectrum could be modeled with very high precision.
1 German Aerospace Center, Institute of Planetary Research, Berlin, 12489, Germany
2 Terahertz and Millimetre Wave Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Göteborg, Sweden
3 Omnisys Instruments AB, Västra Frölunda, 421 32, Sweden
4 Fraunhofer Institute forApplied Solid State Physics IAF, Freiburg, 79108, Germany
5 Technical University of Denmark, DTU Elektro, Kgs. Lyngby, 2800, Denmark
6 Wasa Millimeter Wave AB, SE-412 96 Göteborg, Sweden
7 Goethe Universität, Frankfurt am Main, Frankfurt, Germany
8 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
9 Technische Universität Berlin, Berlin, Germany
Index Terms:
CH3OH, heterodyne receiver, heterostructure barrier varactors, methanol, mHEMT, MMICs, molecular spectroscopy, power amplifiers, Schottky diode, terahertz.
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