ALMA Band 9 cartridge

The Atacama Large Millimeter Array (ALMA) is a collaboration between Europe, North America, and Japan to build an aperture synthesis telescope with more than 50 12-m antennas at 5000 m altitude in Chile. In its full configuration, ALMA will observe in 10 bands between 30 and 950 GHz, and will provide astronomers with unprecedented sensitivity and spatial resolution at millimetre and sub-millimetre wavelengths. Band 9, covering 602-720 GHz, is the highest frequency band in the baseline ALMA project, and will thus offer the telescope's highest spatial resolutions. This paper describes the design of the Band 9 receiver cartridges for the Atacama Large Millimeter Array (ALMA). These are field-replaceable heterodyne front-ends offering high sensitivity, 602-720 GHz frequency coverage, 4-12 GHz IF bandwidth, and high quasioptical efficiencies. Because the project will ultimately require up to 64 cartridges to fully populate the ALMA array, two key aspects of the design of the Band 9 cartridge have been to take advantage of commercial manufacturing capabilities and to simplify the assembly of the cartridge.