Development of the L-band phased array feed for the Five-hundred-meter Aperture Spherical radio Telescope

摘要

Summary form only given. Phased array feed (PAF) is an emerging technology which can greatly improve the survey speed of telescopes. As a world-class radio telescope, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is also trying to enhance its observation capability and open up new scientific studies at several frequency bands by PAFs. At the first part of this paper, the blue print of the FAST PAFs development and corresponding scientific goals are introduced, as well as the progress has been made in these PAFs. Among these multi-beam receivers, the L-band FAST PAF is of the greatest importance and most developed. It is expected to have more than 100 digital formed beams, with cryogenic low noise amplifier, and even cooled feeding array to achieve possible highest sensitivity. Cavity-backed dipoles are adopted to cover the frequency from 1.05 to 1.45 GHz, for the merits of wide bandwidth and lower mutual coupling between elements. This paper presents the details of the L-band PAF design, estimated system performance, and some test results of the first prototype components. Compared with traditional single pixel feeds, another advantage of PAF is adaptive beam-former, which can be employed to compensate the vibration of feed cabin. This will largely reduce the burden of the mechanical positioning system, and improve the pointing accuracy at higher frequencies. Some results of this study will be presented also.