EAGER: Small Motionless Antenna with Reconfigurable Transmission

EAGER：具有可重新配置传输功能的小型静止天线

• 批准号: 1832860
• 负责人: Khai Ngo
• 金额: $ 10.06万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-15 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1832860&HistoricalAwards=false
• 关键词: EAGER; Small; Motionless; Antenna; Reconfigurable

Rescue operations in the wake of a hurricane has been hindered by the absence of a compact apparatus for underwater communication. Data can be transmitted or received through seawater, earth, or other challenging environments at the rate between 1000 and 10,000 events per second by stationary or rotatory methods. The antennae for such transmission ought to be portable so that they can be carried by first responders. Stationary antennae as simple as a loop of wire are not portable as they require kilometers of real estate. Rotatory antennae employing motor(s) driving permanent magnets suffer from reliability, noise, and service duration associated with moving parts. The proposed concept overcomes these shortcomings by avoiding bulk motion in the synthesis of a centimeter-sized antenna swirling a magnetic cloud. It relies on 'variable material' rather than the 'variable structure' on which mechanical rotation relies. Local first responders will be consulted, and their feedback will be used to identify design constraints. Electrical, civil, and ocean engineering students will learn electromagnetism, power electronics, and hardware validation. The main objective of the work plan is to reduce the dimensions of an ultra-low-frequency antenna from kilometers to centimeters. The full proposal proves mathematically that such drastic size reduction requires the generation of a rotating magnetic field. The EAGER novelty is to create such rotating magnetic field without using moving parts. Two pieces of hardware will be designed, constructed, and tested: an ultra-low-frequency antenna and a sensitive magnetometer capable of detecting femto-Teslas. The antenna is constructed from two basic cells. Each basic cell comprises a Neodymium magnet serving as a source of magnetic flux, a ferrite yoke serving as a high-permeability conduit of magnetic flux, and a current-controlled saturable inductor serving as a 'shutter' for magnetic flux. The shutter's core is realized by non-oriented 80% nickel-iron alloy or square-loop ferrite that can be saturated with low control current. At zero control current, the shutter's permeability is high. Since the ferrite yoke's permeability is already high, the flux from the magnet is trapped (no emission) by the shutter and the yoke. As the control current increases, the shutter's permeability decreases to let more flux emit from the magnet. A circular array of basic cells and the associated modulated control currents will generate a spinning magnetic cloud. Simulation of a preliminary design suggests that 100 femto-Teslas at 1000 Hertz would be detected under seawater at 100m away from a two-cell prototype with dimensions of 15 x 9.5 x 3 cubic centimeters. This preliminary design will be refined in the first quarter, and a flux shutter will be constructed. The shutter, ferrite yoke, and permanent magnet will be integrated to realize the antenna in the second quarter. A single-axis induction magnetometer will be designed and tested in the third quarter to measure the expected femto-Teslas at 100 m away. Three-axis magnetometer will be constructed in the fourth quarter to detect the field vector. The power electronics to drive the antenna will be designed and fabricated by the third quarter. The antenna and its driver will be integrated and field-tested in the fourth quarter. The project is deemed successful upon detection of 100 femto-Teslas at 1000 Hertz at 100m distance with an antenna volume less than 450 cubic centimeters, and without moving parts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

飓风过后的救援行动因缺乏紧凑的水下通信设备而受到阻碍。数据可以通过固定或旋转方法以每秒1000到10，000个事件的速率通过海水、地球或其他具有挑战性的环境传输或接收。用于这种传输的天线应该是便携式的，以便第一响应者可以携带。像一圈电线这样简单的固定天线并不便携，因为它们需要数公里的真实的地产。采用驱动永磁体的电机的旋转天线受到与移动部件相关联的可靠性、噪声和服务持续时间的影响。所提出的概念克服了这些缺点，避免了在合成一个厘米大小的天线旋转磁云的大体积运动。它依赖于“可变材料”，而不是机械旋转所依赖的“可变结构”。将咨询当地的第一反应者，他们的反馈将用于确定设计限制。电气，土木和海洋工程专业的学生将学习电磁学，电力电子学和硬件验证。该工作计划的主要目标是将超低频天线的尺寸从几公里减小到几厘米。完整的提案从数学上证明，如此剧烈的尺寸缩小需要产生旋转磁场。EAGER的新奇在于不使用移动部件就能产生这样的旋转磁场。将设计、构建和测试两个硬件：一个超低频天线和一个能够检测飞秒特斯拉的灵敏磁力计。天线由两个基本单元构成。每个基本单元包括用作磁通量源的钕磁体、用作磁通量的高导磁率导管的铁氧体轭和用作磁通量“快门”的电流控制可饱和电感器。快门的核心是实现无取向的80%镍铁合金或方环铁氧体，可以饱和低控制电流。在零控制电流下，快门的磁导率很高。由于铁氧体磁轭的磁导率已经很高，来自磁体的通量被快门和磁轭捕获（无发射）。 随着控制电流的增加，快门的磁导率降低，以使更多的磁通量从磁体发出。基本细胞的圆形阵列和相关的调制控制电流将产生旋转的磁云。对初步设计的模拟表明，在1000赫兹的100个飞秒特斯拉将在距离15 x 9.5 x 3立方厘米的双电池原型100米的海水下被检测到。这一初步设计将在第一季度进行完善，并将建造一个通量快门。快门、铁氧体磁轭和永磁体将在第二季度集成以实现天线。第三季度将设计和测试一个单轴感应磁力计，以测量100米外的预期飞秒特斯拉。三轴磁强计将在第四季度建成，以检测磁场矢量。驱动天线的电力电子设备将在第三季度设计和制造。天线及其驱动器将在第四季度进行集成和现场测试。该项目被认为是成功的检测100毫微微特斯拉在100米的距离在1000赫兹与天线体积小于450立方厘米，没有移动部件。这一奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。