天籁计划射电望远镜中宽带馈源的研制

Wideband feed design for radio telescope of the Tianlai project

暗能量约占宇宙总密度的3/4,但其成团性很弱,且与普通物质的相互作用也极其微弱,很难在实验室内直接进行测量,因此对它的探测主要是考虑其在宇宙尺度上的引力效应,即需要测量不同时期宇宙膨胀的速度H(z)(哈勃参数)。为了实现暗能量的高精度观测,天籁计划正在研制一种针对暗能量探测的专用射电阵列望远镜,其中馈源要求具有宽频带特性。本文将主要提出一种适用于天籁计划需求的宽带馈源型式,通过改进方板偶极子、附加反射腔以及巴伦馈电的结构型式,并用三维电磁仿真软件CST Microwave Studio对不同型式宽带馈源的电性能进行仿真计算,通过结构选优设计获得结构参数,制作了实物模型,经实验测试结果和仿真结果吻合,较好满足项目的需求。

Dark energy makes up about three quarters of the total cosmic density, but its interaction with ordinary matter is very weak ,it is difficult to measure directly in the laboratory, hence its detection mainly considers the effects of gravity on cosmic scales. To achieve the high accuracy observation of dark energy, the Tianlai project will develop a dedicated radio telescope for dark energy detection. As an important part of the radio telescope system, feed＇ s performance directly affects the overall performance of the whole antenna systems. This paper describes the design of a novel feed for the Tianlai project,which comprises four 4-square boards and reflective cavity, and the feed is fed by a standard quarter wave balun which can provide a DC short. The gain and farfield patterns of the feed is calculated with the electromagnetic simulation software CST Microwave Studio. The feed was manufactured and measured, the measured results indicate that the feed achieves the design goal, and the measured results agree well with the simulation results.