Founded in 1946, AUI has been at the forefront of technology and innovation for over 50 years. Since its inception, AUI has been leading the way in the design, construction, and operation of complex, cutting edge, user-oriented facilities, which carry out basic and applied research. The technologies developed at Brookhaven National Laboratory enabled scientific research leading to several Nobel Prizes and had wide applications at the frontier of numerous scientific disciplines. Through its management of the National Radio Astronomy Observatory (NRAO), AUI not only builds and operates the world’s forefront radio observatories, but advances the state of the art in radio science through the NRAO Technology Center and Central Development Laboratory. AUI, through its user facilities and technology advances has helped to create the knowledge and innovation workforce we need to be successful in the global economy and to encourage scientific awareness in the general public
HFET Amplifier Development. Radio astronomy receivers almost universally use cooled HFET (heterostructure field-effect transistor) amplifiers as their low-noise input amplifier. Engineers and scientists at the NRAO Central Development Laboratory (CDL) have worked on the development of these critical receiver components for many years and are largely responsible for their high performance and wide acceptance by the radio astronomy community. NRAO CDL has developed noise models of different HFETs at cryogenic temperatures, and the innovative design techniques developed by CDL engineers yield wideband amplifiers with the optimal noise performance across the band. The HFET amplifiers developed by the NRAO CDL are reliable, stable, and show state-of-the-art performance from 1 – 118 GHz. At frequencies above 1 GHz, these transistors are made on indium phosphide (InP); at lower frequencies, transistors made on gallium arsenide (GaAs) show superior performance.
The CDL has produced hundreds of HFET amplifiers that range from low-frequency amplifiers (< 1 GHz) used in fundamental particle physics and magnetic-resonance imaging development to the highest attainable frequencies for cosmic microwave background experiments. Successful development by the CDL of an InP-based low-noise amplifier at 90 GHz, e.g., was crucial to the success of the Wilkinson Anisotropy Microwave Probe satellite (WMAP). The CDL developed and produced all 80 space-rated amplifiers covering the five WMAP bands, and these were the core technology that enabled this highly successful mission. Other astronomical telescope systems that employ CDL low-noise amplifiers include: the Cosmic Background Imager (CBI), the Degree Angular Scale Interferometer (DASI), the Very Small Array (VSA), the Berkeley Illinois Maryland Association Sunyaev Zeldovitch Array (BIMA SZA), the Expanded Very Large Array (EVLA), and the Atacama Large Millimeter Array (ALMA).
SIS mixers. Mixers that use Superconductor-Insulator-Superconductor (SIS) tunneling junctions to convert millimeter and sub-millimeter waves to intermediate frequencies are the foundations of all ultra-sensitive radio astronomy receivers above 115 GHz. In collaboration with the Microelectronics Laboratory at the University of Virginia, NRAO CDL engineers and scientists led the development of a very reliable niobium (Nb) based junction fabrication process useful in many different superconducting electronic circuits. Years of CDL research and development have led to SIS mixer designs that are broadband, require no mechanical tuners, and achieve record-low noise temperatures.
Large numbers of such SIS mixers have been produced by the CDL for many radio telescopes. PSIS mixers are key components for two Atacama Large Millimeter Array (ALMA) receiver bands. With the Microelectronics Laboratory at the University of Virginia, the CDL is currently developing NbTiN mixers for ALMA use at frequencies above 700 GHz.
Digital correlators. Digital auto- and cross-correlators are the heart of digital data processing for all radio telescopes, and the NRAO CDL has been a world leader in the development and construction of such systems. CDL personnel are currently building the ALMA correlator, the world’s fastest supercomputer, capable of more than 17,000,000,000,000,000 calculations per second using a custom processor chip that was designed at the CDL.
MMIC components. Monolithic Millimeter-Wave Integrated Circuits (MMICs) provide highly repeatable performance in a more compact package than traditional millimeter and centimeter wave assemblies, and at lower cost in large quantities. The NRAO CDL is currently developing MMICs and MMIC-based subsystems for the current and next generation of radio astronomy receivers and arrays. Custom MMIC power amplifiers, multipliers, and mixers have been developed, e.g., for the ALMA local oscillator system. NRAO CDL has developed a MMIC-based prototype Compact Water Vapor Radiometer for the EVLA and is developing custom MMICs and Multi-Chip Modules for NASA's Deep Space Network (DSN) Array, the Square Kilometer Array (SKA), and the Frequency Agile Solar Radiotelescope (FASR).