A way to improve the field of view of large aperture radio telescopes

The proposed new feed is a dense focal-plane array of microstrip antenna elements, the so called Vivaldi antennas. The electro-magnetic properties of the Vivaldi element and Vivaldi array are briefly introduced, which are essential for this application. The focal-field distributions (FFD) of FAST are simulated by using the software package GRASP8 for different illuminations. The simulation results give important information for the layout design of the array, especially for the weighting system of the Vivaldi array. A preliminary configuration of the array structure is suggested, and the illumination patterns are estimated. Finally, some remarks on the feasibility of applying the Vivaldi array to FAST are made.