EAGER: Small Motionless Antenna with Reconfigurable Transmission

由于缺乏紧凑的水下通信设备，飓风过后的救援行动受到了阻碍。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个事件的速率以固定或旋转的方式传输或接收。用于这种传输的天线应该是便携的，这样才能由急救人员携带。像一圈电线一样简单的固定天线是不能携带的，因为它们需要几公里的空间。采用电机(S)驱动永磁体的旋转天线存在与移动部件相关的可靠性、噪音和使用寿命问题。提出的概念克服了这些缺点，在合成厘米大小的旋转磁云的天线时避免了整体运动。它依靠的是“可变材料”，而不是机械旋转所依赖的“可变结构”。将征询当地急救人员的意见，并利用他们的反馈来确定设计限制因素。电气、土木工程和海洋工程专业将学习电磁学、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公里减少到厘米。完整的提议从数学上证明，如此大幅度的尺寸缩小需要产生旋转磁场。令人渴望的新奇之处在于，在不使用移动部件的情况下创造出这样的旋转磁场。将设计、建造和测试两个硬件：一个超低频天线和一个能够探测Femto-Tesla的灵敏磁强计。天线由两个基本单元组成。每个基本单元包括用作磁通量来源的钕磁体、用作高磁导率磁通量管道的铁氧体磁轭、以及用作磁通量“快门”的电流控制可饱和电感。快门的铁芯由无取向80%镍铁合金或方环铁氧体实现，可在低控制电流下饱和。在控制电流为零的情况下，快门的磁导率很高。由于铁氧体磁轭的磁导率已经很高，来自磁体的磁通被快门和磁轭捕获(无排放)。随着控制电流的增加，快门的磁导率降低，从而使更多的磁通从磁体中释放出来。基本单元的圆形阵列和相关的调制控制电流将产生旋转的磁云。初步设计的模拟表明，在距离尺寸为15x9.5x3立方厘米的两单元样机100米处的海水中，可以探测到100个1000赫兹的毫微微-特斯拉。这一初步设计将在第一季度得到完善，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实现天线。将在第三季度设计并测试一台单轴感应磁强计，以测量100米外预期的毫微微-特斯拉。将在第四季度建造三轴磁力仪来探测磁场矢量。驱动天线的电力电子设备将在第三季度之前设计和制造。天线及其驱动器将于第四季度集成并进行现场测试。该项目在1000赫兹、100米距离、天线体积小于450立方厘米且没有移动部件的情况下检测到100个毫微微-特斯拉，被认为是成功的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.