Multi-institutional Team Achieves Fast, Flexible and Accurate Calibration of Radio Telescope Receivers

Arthur W. Lichtenberger, research professor in the University of Virginia’s Charles L. Brown Department of Electrical and Computer Engineering, has earned the 2020 Terahertz Science and Technology best paper award from the Institute of Electronics and Electrical Engineers Microwave Theory and Techniques Society. The award recognizes the most significant contribution by a published paper in 2018.

Lichtenberger and his co-authors from the California Institute of Technology and the Universidad de Concepción of Chile developed a faster and more accurate way to calibrate receivers on radio telescopes. Astronomers need radio telescopes to map gas clouds and stars of far-away galaxies. Complementing the observing dish, the telescope is driven by the receiver or radiometer that is used to measure the average power of the electromagnetic signals from the heavens over a well-defined frequency range. The team’s innovation, called a programmable calibration load, helps astronomers more accurately interpret and understand their observations.

The team achieved system calibration with a compact multi-functional materials micromachined chip that can be easily implanted in the heart of the receiver. The size of the calibration load is compact and connects directly to the device input. Their approach offers a dramatic improvement over standard calibration methods that are manual and binary. By contrast, the team’s calibration load is programmable; adjustments can be done within 10 seconds, allowing astronomers to maintain their focus on the skies rather than the instrument itself.

The ability to program the calibration load on the time scale of seconds allows for significant flexibility in device characterization and in situ calibration. The calibration load not only works as predicted at cryogenic temperatures, but also operates well up to room temperature. In principle, the team should be able to scale the design—to make everything smaller—to work at terahertz frequencies. Their calibration load has a wide range of applications including ultra-low noise millimeter and submillimeter detection systems and space-based missions.

The team’s paper, “A Programmable Cryogenic Waveguide Calibration Load with Exceptional Temporal Response and Linearity,” was published in the July 2018 issue of IEEE Transactions on Terahertz Science and Technology. IEEE will confer the annual award during the June 2020 International Microwave Symposium.