Future of Observations in the mm/sub-mm Range: GARD's Novel Technologies for ALMA and Beyond

Other conference contribution, 2024

The ALMA project has revolutionized mm and sub-mm radioastronomy, enhancing our cosmic understanding from planetary formation to the chemistry of the cosmos. GARD builds on this legacy, advancing the next generation of FIR instrumentation to extend technological limits. This presentation will show several ground-breaking technologies developed at GARD, designed to enhance sensitivity, bandwidth, and the overall observational capabilities of future radio observatories. Central to our advancements is the development of wide-bandwidth SIS mixers, which are engineered to achieve a 56\% fractional bandwidth in the 211-375 GHz frequency range, effectively covering ALMA bands 6 and 7. By incorporating a metallic substrate and employing a metallic fineline waveguide-to-substrate transition, these mixers are tailored to optimize the operational bandwidth of the receivers, and effectively addressing the challenges of dielectric losses. We also highlight significant advancements in the IF backend circuitry, featuring the integration of wideband superconducting bias-T alongside IF transformers and hybrid circuits. The hybrid circuits employ parallel plate coupled line couplers, enabling operation across a broad frequency range from 4 to 20 GHz. Finally, we showcase a quasi-optic, scalable dichroic mirror, initially designed for the Q-band (35-55 GHz) and potentially extendable to THz frequencies. We are exploring 3D printing technology for its manufacturing.