Towards sideband-separation for ALMA's highest bands

Over the last few years, we developed high-performance sideband- separating (2SB) mixers for 600-720 GHz (Band 9) and 790-950 GHz (Band 10). The former have successfully been commissioned in the SEPIA front- end at APEX. On-sky image rejection ratios in excess of 24dB have been recorded for the CO(6-5) line at 691 GHz and the water maser line at 658 GHz, while lab testing shows 15dB or better over an extended RF band of about 580-740GHz. Noise temperature is better than 200K (SSB) over most of the band. The receiver cartridge has four 4-12 GHz IF outputs and is fully ALMA-frontend compatible. We intend to extend the IF bandwidth even further in the near future. The new Band 790-950 GHz 2SB mixer (intended for the FLASH front-end at APEX) has been tested in the lab recently and shows comparable performance characteristics. We see these mixers, with circulator-less wideband IF infrastructure, as an attractive upgrade for the highest ALMA bands

A Martin-Puplett Interferometer Side-Band Separation Module for 600 – 720 GHz

A side-band separation receiver module for the 600 to 720 GHz ALMA band is proposed. The design is based on a cold Martin-Puplett Interferometer (MPI) with reflective optics. The operation principle and design parameters of the module are presented. The MPI SSB module performance with lossless optical components is compared with a DSB module using the same mixer and taking into account an atmospheric model for the 600 to 720 GHz band

ALMA Band 9 Optical Layout

In this report a mm wave optics prototype for an Atacama Large Millimeter Array (ALMA) receiver cartridge is discussed. Mainly the ALMA frequency band 9 (602-720 GHz) is considered. However the same design approach is applicable to the receiver optics of any other ALMA bands. The high frequency cartridges (bands 7-10) have been decided to have no intermediate optics between the telescope secondary mirror and the cartridge cold optics. (See notes of Tucson optics meeting). Consequently, in the optical design of band 9 cartridge full signal path with all focusing elements are considered as free design parameters. In this report a concept of choosing and optimizing these parameters is discussed. The design starts from an optimal corrugated and diagonal horn field representation. A possibility of distortion compensation by a pair of ellipsoidal mirrors is discussed. A concept of frequency independent radiation coupling between the horn and the Cassegrain telescope system is presented. An expression for parameters of two elliptical mirrors giving rise to frequency independent matching of the horn to the telescope is given. A practical corrugated horn for signal path of mixer and a practical diagonal horn for local oscillator (LO) part of mixer are proposed. Based on the horn and the ALMA prototype antenna design a two-mirror layout for ALMA band 9 is proposed. The alignment accuracy of optical components within the cartridge is considered. The alignment accuracy between the cartridge and the secondary mirror is also considered

Development status of a 420–1980 GHz vector network analyzer for time-domain reflectometry and imaging applications

With recent progress in the area of electronically tunable solid-state sources it is possible to fully extend microwave measurement techniques into the THz frequency range. In this paper we present the development status of a 420-1980 GHz vector network analyzer and illustrate how phase-sensitive heterodyne techniques can be used in the area of THz reflectometry and imaging