A three-position spectral line survey of Sagittarius B2 between 218 and 263 GHz. I. The observational data

We have surveyed the frequency band 218.30-263.55 GHz toward the core positions N and M and the quiescent cloud position NW in the Sgr B2 molecular cloud using the Swedish-ESO Submillimetre Telescope. In total 1730, 660, and 110 lines were detected in N, M, and NW, respectively, and 42 different molecular species were identified. The number of unidentified lines are 337, 51, and eight. Toward the N source, spectral line emission constitutes 22% of the total detected flux in the observed band, and complex organic molecules are the main contributors. Toward M, 14% of the broadband flux is caused by lines, and SO2 is here the dominant source of emission. NW is relatively poor in spectral lines and continuum. In this paper we present the spectra together with tables of suggested line identifications.

A 330-360 GHz spectral survey of G34.3+0.15 .2. Chemical modelling

We describe a detailed depth-and time-dependent model of the molecular cloud associated with the ultracompact H II region G 34.3+0.15. Previous work on observations of NH3 and CS indicates that the molecular cloud has three distinct physical components:- an ultracompact hot core, a compact hot core and an extended halo. We have used the physical parameters derived from these observations as input to our detailed chemical kinetic modelling. The results of the model calculations are discussed with reference to the different chemistries occuring in each component and are compared with abundances derived from our recent spectral line survey of G 34.3+0.15 (Paper I).

A 330-360 GHz spectral survey of G 34.3+0.15 .1. Data and physical analysis

A 330--360 GHz spectral survey of the hot molecular core associated with the 'cometary' ultracompact HII region G 34.3+/-0.15 observed with the James Clerk Maxwell Telescope has detected 338 spectral lines from at least 35 distinct chemical species plus 19 isotopomers. 70 lines remain unidentified. Chemical abundance and rotation temperature have been determined by rotation diagram analysis for 12 species, and lower limits to abundance found for 38 others.

Ultrafast Low-Loss 40-70 GHz SPST Switch

The design and characterizations of an ultrafast single-pole single-throw (SPST) absorptive differential switch are presented. The switch exhibits low insertion loss less than 1 dB, and isolation better than 16 dB from 40 to 70 GHz. Sub-nanosecond switching time is achieved by adopting a differential current-steering technique. The total measured rise and fall time are 75 ps envisaging that switching rates up to 13 Gb/s are achievable. To our best knowledge, this is the fastest, lowest insertion loss V-band SPST switch yet reported that can operate over a wide bandwidth of 30 GHz.