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4 results on '"Ugras N"'

1. Low-noise slot antenna SIS mixers

Author

Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., Stern, J. A., Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., and Stern, J. A.

Abstract

We describe quasi-optical SIS mixers operating in the submillimeter band (500-750 GHz) which have very low noise, around 5 h/spl nu//k/sub B/ for the double-sideband receiver noise temperature. The mixers use a twin-slot antenna, Nb/Al-Oxide/Nb tunnel junctions fabricated with optical lithography, a two-junction tuning circuit, and a silicon hyperhemispherical lens with a novel antireflection coating to optimize the optical efficiency. We have flown a submillimeter receiver using these mixers on the Kuiper Airborne Observatory, and have detected a transition of H/sub 2//sup 18/O at 745 GHz. This directly confirms that SIS junctions are capable of low-noise mixing above the gap frequency.

Published
1995

2. Low-noise slot antenna SIS mixers

Author

Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., Stern, J. A., Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., and Stern, J. A.

Abstract

We describe quasi-optical SIS mixers operating in the submillimeter band (500-750 GHz) which have very low noise, around 5 h/spl nu//k/sub B/ for the double-sideband receiver noise temperature. The mixers use a twin-slot antenna, Nb/Al-Oxide/Nb tunnel junctions fabricated with optical lithography, a two-junction tuning circuit, and a silicon hyperhemispherical lens with a novel antireflection coating to optimize the optical efficiency. We have flown a submillimeter receiver using these mixers on the Kuiper Airborne Observatory, and have detected a transition of H/sub 2//sup 18/O at 745 GHz. This directly confirms that SIS junctions are capable of low-noise mixing above the gap frequency.

Published
1995

3. Submillimeter spectroscopy of interstellar hydrides

Author

Haas, Michael R., Davidson, Jacqueline A., Erickson, Edwin F., Zmuidzinas, J., Blake, G. A., Carlstrom, J., Keene, J., Miller, D., Schilke, P., Ugras, N. G., Haas, Michael R., Davidson, Jacqueline A., Erickson, Edwin F., Zmuidzinas, J., Blake, G. A., Carlstrom, J., Keene, J., Miller, D., Schilke, P., and Ugras, N. G.

Abstract

We discuss airborne observations of rotational transitions of various hydride molecules in the interstellar medium, including H_2^(18)O and HCI. The detection of these transitions is now feasible with a new, sensitive submillimeter receiver which has been developed for the NASA Kuiper Airborne Observatory (KAO) over the past several years.

Published
1995

4. Low-noise slot antenna SIS mixers

Author

Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., Stern, J. A., Zmuidzinas, J., Ugras, N. G., Miller, D., Gaidis, M., LeDuc, H. G., and Stern, J. A.

Abstract

We describe quasi-optical SIS mixers operating in the submillimeter band (500-750 GHz) which have very low noise, around 5 h/spl nu//k/sub B/ for the double-sideband receiver noise temperature. The mixers use a twin-slot antenna, Nb/Al-Oxide/Nb tunnel junctions fabricated with optical lithography, a two-junction tuning circuit, and a silicon hyperhemispherical lens with a novel antireflection coating to optimize the optical efficiency. We have flown a submillimeter receiver using these mixers on the Kuiper Airborne Observatory, and have detected a transition of H/sub 2//sup 18/O at 745 GHz. This directly confirms that SIS junctions are capable of low-noise mixing above the gap frequency.

Published
1995

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