Coherent Detection and Sis Mixers
نویسنده
چکیده
Submillimeter spectroscopy is a unique and very rich source of astrophysical information. While many important results have been obtained using ground based telescopes, the Kuiper Airborne Observatory, ISO, and SWAS, this field will soon experience rapid growth and development due to projects such as SOFIA, ALMA, and the Herschel Space Observatory (HSO). High spectral resolution is and will continue to be important for many observations. This paper discusses the relative merits of coherent and direct detection for high resolution spectroscopy. In addition, the paper gives a brief review of the status of coherent detection, and superconducting tunnel junction (SIS) mixers in particular. Coherent detection can be expected to play a key role in submillimeter and far–infrared astrophysics well into the future.
منابع مشابه
Saturation by Noise and CW Signals in SIS Mixers
In ALMA Memo 321, Plambeck points out that saturation (gain compression) is likely to be a significant factor limiting the calibration accuracy of ALMA observations. In this memo, saturation by broadband noise and CW signals is analyzed for representative SIS receivers operating at different frequencies. Many SIS mixers in current use are expected to exhibit a significant degree of gain compres...
متن کاملTHz SIS mixers with normal-metal Al tuning circuits
Nb-based superconductor–insulator–superconductor (SIS) mixers with Nb tuning circuits have demonstrated good results up to the Nb gap frequency. Above the gap frequency the performance is expected to degrade quickly because RF loss in Nb becomes significant. In this paper we present the results of an effort to extend Nb-based SIS mixers to THz frequencies by employing lower-loss normal-metal Al...
متن کاملA Superconducting 180° IF Hybrid for Balanced SIS Mixers
A compact 180° hybrid has been developed for use in balanced SIS mixers. The lumped-element circuit uses superconducting Nb conductors on a 1.4 mm x 0.5 mm quartz substrate and operates over 4-12 GHz. Index TermsSuperconducting microwave devices, microwave integrated circuits, hybrid junctions, lumpedelement microwave circuits, superconductor-insulatorsuperconductor mixers.
متن کاملCharacterization of submillimetre quasi-optical twin-slot double-junction SIS mixers
We report on the continuing development of submillimetre quasi-optical slot antenna SIS mixers, which use two-junction tuning circuits. Direct and heterodyne Fourier transform spectrometer measurements have been performed to compare device performance with predictions. Demonstrated double-sideband receiver noise temperatures of better than 540 K at 808 GHz make these SIS mixers substantially be...
متن کاملCharacterization of Low-Noise Quasi-Optical SIS Mixers for the Submillimeter Band - Microwave Theory and Techniques, IEEE Transactions on
AbstructWe report on the development of low-noise quasioptical SIS mixers for the frequency range 400-850 GHz. The mixers utilize twin-slot antennas, two-junction tuning circuits, and Nb-trilayer junctions. Fourier-transform spectrometry has been used to verify that the frequency response of the devices is well predicted by computer simulations. The 400-850 GHz frequency band can be covered wit...
متن کامل