Novel High Performance Feed Horns for Large Format Arrays at Millimetre and Submillimetre Wavelengths.

对于毫米和亚毫米波长的许多科学目标来说，能够以高灵敏度快速绘制大片天空地图是至关重要的。下一代望远镜将把数百或数千个喇叭送入焦平面阵列接收器中，向超灵敏探测器供电。因此，快速、可靠、成本可控地制造大量高质量的望远镜馈源喇叭的能力至关重要。传统上，无线电和亚毫米望远镜接收器的焦平面阵列使用波纹喇叭将来自天空的能量耦合到探测器。这是因为它们在高达50%的带宽上表现出极佳的波束方向图。然而，为了提供所需的高性能，这些喇叭的内部必须有许多1/4波长的深方位槽(波纹)。这使得它们在波长越来越小的情况下变得极其困难和昂贵。对于具有成百上千个这样的喇叭的下一代大幅面焦平面阵列，仅波纹喇叭的成本就可以占整个接收器成本的很大一部分(~50%)。波纹喇叭的另一个缺点是，墙面需要足够厚，以容纳相对较深的波纹。这使得它们对于空间望远镜和微波频率的通信系统等关键应用来说太重了，在这些应用中，只有几个喇叭的重量可能被证明是有问题的。牛津天体物理学研究小组与泰国Mahidol大学的研究人员合作，开发出了比波纹喇叭更容易制造、成本更低的光滑喇叭。这些喇叭只需要在喇叭喉部附近的耀斑角度中有一个或多个不连续，就可以激发高阶波导模的正确平衡。我们使用我们为此目的开发的软件套件来优化这些不连续的位置。我们经过充分优化的喇叭在显著(30%)的工作带宽上显示出极佳的波束方向图。我们喇叭设计的相对简单的几何形状允许使用快速、低成本的制造技术来制造它们。我们已经开发出一种技术，通过使用适当形状的刀具将牛角钻成一块铝来直接加工牛角。这项技术将使快速制造大尺寸的喇叭阵列成为可能，只需在一块铝板上重复钻孔即可。我们利用这种技术成功地制作并测试了单个230 GHz喇叭原型，发现它们从理论上给出了预期的波束方向图。高性能牛津光壁饲料变幅杆的商机是巨大的，以一半的价格，它们很可能在许多应用中取代传统的波纹变幅杆。目标市场将包括建造毫米和亚毫米天文接收器、遥感地球遥感、天基卫星通信以及陆基电信和雷达应用的研究小组。在这项拨款申请中，我们请求支持开发一项全新的技术，这是STFC支持的学术研究的副产品。因此，需要相对较少的开发资金就能使其进入商业化阶段。这些产品包括软件许可、根据客户规格进行设计，以及成本不到现有技术的一半、交付时间快得多的产品。我们的商业化努力得到了牛津大学技术转让子公司Isis Innovation Limited的支持。

The ability to rapidly map large areas of the sky to a high sensitivity is of prime importance for many scientific goals at mm and sub-mm wavelengths. The next generation of telescopes will incorporate hundreds or thousands of horns feeding ultra-sensitive detectors into focal plane array receivers. Therefore, the ability to manufacture large numbers of high quality telescope feed horns rapidly, reliably and at a manageable cost is vitally important. Traditionally, focal plane arrays of radio and submillimeter telescope receivers have employed corrugated horns to couple power form the sky to the detectors. This is because they exhibit excellent beam patterns over bandwidths of up to 50%. To give the required high performance however, these horns must have many 1/4 wavelength deep azimuthal grooves (corrugations) along their interiors. This makes them extremely difficult and expensive at increasingly smaller wavelengths. For the next generation of large format focal-plane arrays, with many hundreds or thousands of such horns, the cost of the corrugated horns alone can be a significant fraction (~50%) of the entire cost of the complete receiver. Another disadvantage of corrugated horns is that the wall needs to be thick enough to accommodate relatively deep corrugations. This makes them too heavy for key applications such as space telescopes and communication systems at microwave frequencies where the weight of only a few horns could prove to be problematic. The Oxford Astrophysics group have developed smooth-walled horns which are much easier and cheaper to fabricate than corrugated horns, in collaboration with researchers at Mahidol University, Thailand. These horns only require one or more discontinuities in the flare angle near the throat of the horn to excite the right balance of higher-order waveguide modes. We optimise the positions of these discontinuities, using a software suite that we have developed for this purpose. Our fully optimized horns show excellent beam pattern over a significant (30%) operating bandwidth. The relatively simple geometry of our horn designs allows them to be manufactured using rapid, low-cost fabrication techniques. We have developed a technique which involves directly machining the horns by using an appropriately shaped tool to drill the horns into a block of aluminum. This technique will make it possible to quickly fabricate large format arrays of horns by simply drilling repeatedly into a single plate of aluminum. We have successfully fabricated and tested individual prototype 230 GHz horns using this technique and found that they give the expected beam patterns by theory. The commercial opportunity for the high performance Oxford smooth-walled feed horns is massive and at half the price, they are likely to replace the conventional corrugated horns in many applications. The target markets would include research groups building mm and sub-mm astronomical receivers, remote earth sensing, space based satellite communications and earth based telecommunications and radar applications. In this grant application we are requesting support to develop a completely new technology which is a spin-off of academic research supported by the STFC. As a result a relatively small amount of development fund is required to bring it to the stage of commercialisation. The products includes software licensing, design according to customer specifications and a product at less then half the cost of existing technology and much faster time of delivery. Our effort of commercialisation is supported by Isis Innovation Limited, the technology transfer subsidiary company of the University of Oxford.