For decades, scientists have observed the cosmos with radio antennas to visualize the dark,distant regions of the universe. This includes the gas and dust of the interstellar medium, planet-forming disks, and objects invisible to the naked eye. The Atacama large Millimeter/Submillimeter Array (ALMA) in Chile is a leading example of a powerful radio telescope. Utilizing 66 parabolic antennas, ALMA detects millimeter and sub-millimeter radiation emitted by cold molecular clouds where new stars form.
Each antenna features high-frequency receivers covering ten wavelength ranges, from 35 to 50 gigahertz and 787 to 950 GHz, defined as Band 1. Recently, ALMA received a important upgrade thanks to the Fraunhofer Institute for Applied Solid State Physics (IAF) and the Max Planck Institute for Radio Astronomy: 145 new low-noise amplifiers (LNAs). These amplifiers extend the facilities’ Band 2 coverage, operating between 67 and 116 GHz. This broadened range will empower researchers to study the universe with greater detail.
Researchers aim to gain new insights into the “cold interstellar medium”—the dust, gas, radiation, and magnetic fields that birth stars.The upgrade enables more detailed studies of planet-forming disks and facilitates the identification of complex organic molecules in distant galaxies, possibly precursors to life. Ultimately,these studies will illuminate the formation and evolution of stars,planetary systems,and the emergence of life itself.
Advanced Amplifiers Enhance ALMA Sensitivity
Each LNA incorporates monolithic microwave integrated circuits (MMICs) developed by Fraunhofer IAF, utilizing indium gallium arsenide. These MMICs are built using metamorphic high-electron-mobility transistor technology,which creates advanced transistors optimized for high-frequency receivers. The lnas amplify faint signals and reduce background noise,considerably boosting ALMA’s receiver sensitivity.
Fabian Thome, head of the subproject at fraunhofer IAF, stated in an IAF press release:
The performance of receivers depends largely on the performance of the first high-frequency amplifiers installed in them. Our technology is characterized by an average noise temperature of 22 K, which is unmatched worldwide. With the new LNAs, signals can be amplified more than 300-fold in the first step. “This enables the ALMA receivers to measure millimeter and submillimeter radiation from the depths of the universe much more precisely and obtain better data.We are incredibly proud that our LNA technology is helping us to better understand the origins of stars and entire galaxies.
The European Southern Observatory commissioned both Fraunhofer IAF and the Max Planck Institute for Radio Astronomy to develop the amplifiers. Fraunhofer IAF designed, manufactured, and tested the MMICs at room temperature, while Max Planck assembled and qualified the LNA modules, followed by cryogenic testing. “This is a fantastic recognition of our fantastic collaboration with Fraunhofer IAF, which shows that our amplifiers are not only ‘made in Germany’ but also the best in the world,” said michael Kramer, executive director at the Max Planck Institute for Radio Astronomy.
