National Institute for Astro Physics Designs Innovative Phased Arrays for Radio Astronomy Applications
Divisions of the National Institute for Astro Physics of the Institute of Radio Astronomy (INAF-IRA) in Bologna, Italy and the Cagliari Astronomical Observatory (INAF-OACa) in Cagliari, Italy conduct research into the physics of radio sources such as active galactic nucleus (AGN) and galaxies, clusters of galaxies, the galaxy stars and star formation, and cosmology. The Institute was extensively involved in the design, construction, and testing of the Sardinia radio telescope (SRT), a new 64-meter antenna that is part of the very long baseline interferometry (VLBI) global network.
High-sensitivity, large-scale surveys are an essential tool for new discoveries in radio astronomy. INAF designers were challenged to develop, fabricate, and test a room temperature, multi-channel heterodyne receiver operating across the 2.3–8.2 GHz RF band for radio astronomy applications. A phased-array feed (PAF) placed at the focal plane of an antenna can increase the field of view and mapping efficiency by fully sampling the sky. A phased array for reflector observing systems (PHAROS) is a cryogenically cooled PAF demonstrator with analog beamformer based on an array of dual polarization 10 x 11 Vivaldi antennas designed for radio astronomy observations. The new upgraded version, PHAROS 2, utilizes new components to reduce the system noise temperature, enhance the aperture efficiency, and digitize the signals from a sub-array of 24 single-polarization PAF antenna elements that synthesize four independent single polarization beams.
The wide bandwidth and high-performance receiver requirements call for precise electrical modeling of the individual components and RF characterization of the multi-layer printed-circuit board (PCB) substrate in order to achieve the accurate simulation results necessary for successful design.
INAF IRA designers used the Microwave Office circuit simulator within the AWR Design Environment platform to design the PCB circuitry of the receiver chains. The AXIEM 3D EM planar simulator was used to simulate the electromagnetic (EM) response of all interconnecting transmission lines and distributed BPFs. Microwave Office software was employed to optimize the overall performance of the entire receiver chain of a PCB populated with surface-mount technology (SMT) components.
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