Design of an L-Band Cross-Dipole Phased Array Feed for FAST

Yubing Han,Luoqing Zhong

doi:10.1155/2016/5357368

Abstract

The Five-Hundred-Meter Aperture Spherical Telescope (FAST) is a Chinese megascience project that aims to build the largest single dish radio telescope in the world. Given its multiple simultaneous beam formation, phased array feed (PAF) is widely used to extend the field of view and enhance the survey speed of the radio telescope. In this study, a broadband and low cost PAF element using cross-dipole antenna at L-band is designed based on the requirement of the FAST. The antenna is fed by two microstrip baluns which have high performance and is easy to manufacture compared to the traditional coaxial balun. A simple system model is also introduced to evaluate the PAF performance. The measured results of the fabricated element and the simulations of the system performance validate the effectiveness of element design.

Highlights

Observation at radio wavelength has acquired a great scientific and applied importance in the field of astronomy
The Brigham Young University (BYU) radio astronomy group has been working with the National Radio Astronomy Observatory (NRAO) to develop phased array feed (PAF) on NRAO’s 20-meter dish in Green Bank, West Virginia [4]
Incident signals from the universe are reflected by the reflector and received by the PAFs placed at the focal point of the reflector dish

Summary

Introduction

Observation at radio wavelength has acquired a great scientific and applied importance in the field of astronomy. A novel method for enhancing the performance of reflector telescopes is to employ a phased array feed (PAF). Compared with traditional cluster horn feeds, PAFs can provide steerable beams over a continuous field of view to increase survey speed. This method increases sensitivity and provides a means to mitigate radio frequency interference. Several international groups employ PAFs for radio astronomy. Nine groups of feed working together with the receiver cover a frequency range from 70 MHz to 3 GHz. According to the performance specification of L-band PAF, a broadband cross-dipole array is designed in this paper According to the performance specification of L-band PAF in Table 2, a broadband cross-dipole array is designed in this paper

Phased Array Feed System

C Focal plane

PAF Configuration

Element Design

Results

Conclusion