Multiple flare-angle horn feeds for sub-mm astronomy and cosmic microwave background experiments
Multiple flare-angle horn feeds for sub-mm astronomy and cosmic microwave background experiments
复制标题
DOI：
10.1051/0004-6361/201117124
复制
发表时间：
2011-08
影响因子：
6.5
通讯作者：
J. Leech;B. Tan;G. Yassin;P. Kittara;S. Wangsuya;J. Treuttel;M. Henry;M. Oldfield;P. Huggard
中科院分区：
文献类型：
--
作者：
J. Leech;B. Tan;G. Yassin;P. Kittara;S. Wangsuya;J. Treuttel;M. Henry;M. Oldfield;P. Huggard
语境。对于下一代单碟亚毫米望远镜和宇宙学实验来说，使用采用多个馈源喇叭的大画幅焦平面成像阵列变得越来越重要。此类接收器正在通用、普通用户望远镜和专为绘制宇宙微波背景（CMB）中的强度和偏振各向异性而设计的望远镜上进行调试。目前正在建造的望远镜用于绘制 CMB 偏振图，需要使用数百个馈源，而制造这些馈源的成本已成为望远镜总成本的很大一部分。目标。我们开发和制造了低成本、易于加工的光滑壁喇叭，其性能可与焦平面阵列中常用的更传统的波纹馈电喇叭相媲美。我们的喇叭比波纹喇叭更容易制造，能够以非常低的成本快速构建具有大量喇叭的阵列。方法。我们的光滑壁喇叭利用张角的多次变化来激发高阶波导模式。它们的设计使用遗传算法来优化这些张角不连续性的位置和大小。我们开发了一套完全并行的软件套件来优化这些喇叭。我们通过传统电铸和新的直接钻孔技术制造了原型喇叭，并使用 230 GHz 的远场天线测试范围测量了它们的波束方向图。结果。我们为我们的一种喇叭设计提供了模拟和测量的远场光束模式。它们在 20% 的分数带宽上表现出低旁瓣水平、良好的光束圆度和低交叉偏振水平。这些结果为我们的设计技术提供了实验证实，使我们能够自信地继续优化具有更宽工作带宽的喇叭。结果还表明，使用钻孔的新制造技术是成功的，可以通过在单个铝板上重复钻孔来制造大型阵列。这将使每个喇叭以非常低的成本构建焦平面阵列。结论。我们开发了一种新型高性能馈源喇叭，其制造快速且易于。通过实验证明了我们的喇叭设计的功效后，我们正在构建并测试由 37 个六边形密排喇叭组成的原型焦平面阵列。该原型阵列将是使用这些馈源喇叭构建完整的 CMB 映射接收器的重要一步。
Context. The use of large-format focal plane imaging arrays employing multiple feed horns is becoming increasingly important for the next generation of single dish sub-mm telescopes and cosmology experiments. Such receivers are being commissioned on both general purpose, common user telescopes and telescopes specifically designed for mapping intensity and polarisation anisotropies in the cosmic microwave background (CMB). Telescopes are currently being constructed to map the CMB polarisation that employ hundreds of feeds and the cost of manufacturing these feeds has become a significant fraction of the total cost of the telescope. Aims. We have developed and manufactured low-cost easy-to-machine smooth-walled horns that have a performance comparable to the more traditional corrugated feed horns that are often used in focal plane arrays. Our horns are much easier to fabricate than corrugated horns enabling the rapid construction of arrays with a large number of horns at a very low cost. Methods. Our smooth walled horns use multiple changes in flare angle to excite higher order waveguide modes. They are designed using a genetic algorithm to optimise the positions and magnitudes of these flare angle discontinuities. We have developed a fully parallelised software suite for the optimisation of these horns. We have manufactured prototype horns by traditional electroforming and also by a new direct drilling technique and we have measured their beam patterns using a far-field antenna test range at 230 GHz. Results. We present simulated and measured far-field beam patterns for one of our horn designs. They exhibit low sidelobe levels, good beam circularity and low cross-polarisation levels over a fractional bandwidth of 20%. These results offer experimental confirmation of our design technique, allowing us to proceed confidently in the optimisation of horns with a wider operational bandwidth. The results also show that the new manufacturing technique using drilling is successful, enabling the fabrication of large format arrays by repeatedly drilling into a single aluminium plate. This will enable the construction of focal plane arrays at a very low cost per horn. Conclusions. We have developed a new type of high performance feed horn that is fast and easy to fabricate. Having demonstrated the efficacy of our horn designs experimentally, we are building and testing a prototype focal plane array of 37 hexagonally close packed horns. This prototype array will be an important step towards building a complete CMB mapping receiver using these feed horns.