EAGER: Small Motionless Antenna with Reconfigurable Transmission

飓风过后的救援行动由于缺乏用于水下通讯的紧凑型设备而受阻。数据可以通过海水、地球或其他具有挑战性的环境以每秒1000到10,000次的速率通过固定或旋转方法传输或接收。用于这种传输的天线应该是便携式的，以便急救人员可以携带。固定的天线就像一圈电线一样简单，不便于携带，因为它们需要数公里的空间。采用电机驱动永磁体的旋转天线受到与运动部件相关的可靠性，噪音和使用时间的影响。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时的大块运动。它依赖于“可变材料”，而不是机械旋转所依赖的“可变结构”。将咨询当地的急救人员，并使用他们的反馈来确定设计限制。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。工作计划的主要目标是将超低频天线的尺寸从公里缩小到厘米。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的新颖之处在于不使用活动部件就能产生这样的旋转磁场。将设计、制造和测试两种硬件：一种是超低频天线，另一种是能够探测飞特斯拉的灵敏磁力计。天线由两个基本单元构成。每个基本单元包括一个钕磁铁作为磁通源，一个铁氧体轭作为磁通的高导率管道，以及一个电流控制的可饱和电感器作为磁通的“快门”。百叶窗的核心是由无取向的80%镍铁合金或方环铁氧体实现的，可以在低控制电流下饱和。在零控制电流时，百叶窗的磁导率高。由于铁氧体轭的磁导率已经很高，磁铁的磁通被百叶窗和轭捕获（没有发射）。随着控制电流的增加，百叶窗的磁导率降低，使更多的磁通从磁铁中发射出来。基本单元的圆形阵列和相关的调制控制电流将产生旋转磁云。初步设计的模拟表明，在距离尺寸为15 x 9.5 x 3立方厘米的双电池原型机100米远的海水下，可以探测到1000赫兹的100飞特斯拉。这一初步设计将在第一季度进行完善，并将建造一个通量百叶窗。快门、铁氧体轭和永磁体将在第二季度集成以实现天线。将在第三季度设计并测试单轴感应磁力计，以在100米外测量预期的飞特斯拉。第四季度将建造三轴磁强计来探测磁场矢量。驱动天线的电力电子器件将在第三季度完成设计和制造。天线及其驱动程序将在第四季度进行集成和现场测试。在天线体积小于450立方厘米的情况下，在100米距离内探测到1000赫兹的100飞特斯拉，被认为是成功的项目。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.