Design Study of an L-Band Phased Array Feed for Wide-Field Surveys and Vibration Compensation on FAST

Phased array feeds (PAFs) for large diameter single dish radio telescopes offer the capability for multiple simultaneous beam formation and wide field-of-view surveys. An L-band PAF front end design is presented for the Five-hundred-meter Aperture Spherical Telescope (FAST), which is currently under construction and when complete will be the largest single dish radio telescope in the world. A broadband PAF element at L-band was designed in conjunction with the FAST optics and focal plane field distribution, fabricated, and tested. The simulated performance of the array meets the FAST PAF performance requirements for field of view, efficiency, sensitivity, and other key parameters. A unique aspect of the FAST PAF is the need for feed cabin vibration compensation. A study of the use of adaptive beamforming to compensate for lateral movement is given.