Wideband technology development to increase the RF and instantaneous bandwidth of ALMA receivers

Abstract

NAOJ have studied wideband receiver technologies at submillimeter wavelengths toward implementation as future upgrades into the Atacama Large Millimeter/submillimeter Array telescope. We have developed critical components and devices such as waveguide components and superconductor-insulator-superconductor (SIS) mixers targeting radio frequencies (RF) in the 275-500 GHz range and an intermediate frequency (IF) bandwidth of 3-22 GHz. Based on the developed components, quantum-limited low-noise performance has been demonstrated by using a double-sideband receiver frontend in combination with a high-speed digitizer. In addition, a preliminary demonstration of a wideband RF/IF sideband-separating SIS mixer was performed. This paper describes the status of our efforts to develop technology toward wideband receivers for ALMA.