2006年10月23日
A team led by scientists atDuke University's Pratt School of Engineering展示了第一个工作的“隐身斗篷”。斗篷偏转微波梁，使它们在内部的“隐藏”物体周围流动，几乎没有失真，这几乎似乎根本没有任何东西。
Cloaks that render objects essentially invisible to microwaves could have a variety of wireless communications or radar applications, according to the researchers.
该小组报告了其在《科学》（Science Express）的发现，即欧洲杯线上买球《科学杂志》的预先在线出版物。该研究由情报界的博士后奖学金计划资助。
The researchers manufactured the cloak using "metamaterials" precisely arranged in a series of concentric circles that confer specific electromagnetic properties. Metamaterials are artificial composites that can be made to interact with electromagnetic waves in ways that natural materials cannot reproduce (http://www.ee.duke.edu/~drsmith/neg_ref_home.htm).
科学家说，斗篷代表了“尚未设计和生产的最精致的超材料结构之一”。他们补充说，它还代表了尚未实现的最全面的看法，有可能隐藏任何大小或材料属性的对象。
Earlier scientific approaches to achieving "invisibility" often relied on limiting the reflection of electromagnetic waves. In other schemes, scientists attempted to create cloaks with electromagnetic properties that, in effect, cancel those of the object meant to be hidden. In the latter case, a given cloak would be suitable for hiding only objects with very specific properties.
奥古斯丁学者兼杜克大学电脑和计算机工程学教授戴维·R·史密斯（David R. Smith）表示：“通过合并复杂的材料特性，我们的斗篷允许隐藏的体积和斗篷在外部观看时具有类似于自由空间的特性。”“斗篷既减少了物体的反射又减少其阴影，这两者都可以检测到它。”
该小组根据伦敦帝国学院的约翰·彭德里爵士（John Pendry）与杜克大学（Duke Scientors）合作提出的新设计理论确定的电磁规范制作了斗篷。科学家报告说，今年早些时候的理论科学工作（http://www.pratt.duke.edu/ne欧洲杯线上买球ws/?id=433）。
The principles behind the cloaking design, though mathematically rigorous, can be applied in a relatively straightforward way using metamaterials, said cloak designer David Schurig, a research associate in Duke's electrical and computer engineering department (http://www.ece.duke.edu/~dschurig/).
Schurig说：“首先，人们想象空间中的失真类似于将尖头物体推到一块布上时会发生的事情，但扭曲但不会破坏任何线程。”“在这样的空间中，光或其他电磁波将局限于扭曲的'线程'，因此无法与所得孔中放置的物体相互作用或'See，“看到”。
The researchers used a mathematical description of that concept to develop a blueprint for a cloak that mimics the properties of the imagined, warped space, he said.
"You cannot easily warp space, but you can achieve the same effect on electromagnetic fields using materials with the right response," Schurig continued. "The required materials are quite complex, but can be implemented using metamaterial technology."
While the properties of natural materials are determined by their chemistry, the properties of metamaterials depend instead on their physical structure. In the case of the new cloak, that structure consists of copper rings and wires patterned onto sheets of fiberglass composite that are traditionally used in computer circuit boards.
为了简化当前研究中的设计和制造，该团队着手开发一个小于五英寸的小型斗篷，这将在二维而不是三个方面提供隐形性。从本质上讲，斗篷包括成型的超材料的条带成同心二维环，该设计允许其与微波辐射的狭窄光束一起使用。在其表面上构图的铜元素形状的精确变化决定了它们的电磁特性。
研究人员说，斗篷设计在超材料的圆形几何形状和内部结构变化中是独一无二的。欧洲杯足球竞彩所有其他超材料均基于立方体或欧洲杯足球竞彩网格样设计，并且大多数具有电磁特性，这些特性在整个过程中都均匀。
史密斯说：“与其他超材料不同，斗篷需欧洲杯足球竞彩要逐渐改变其性质作为位置的函数。”“斗篷的材料特性并非到处都是相同的，而是在点之间各不相同，并且以非常特定的方式变化。实现材料特性中的梯度是一项相当重要的设计工作。”
为了评估斗篷的性能，研究人员将微波梁瞄准了位于测试室内两个金属板之间的斗篷，并使用了专门的检测设备来测量在斗篷内外开发的电磁场。通过检查数据的动画表示，他们发现梁的波正面分开并在斗篷的中心围绕。
"The waves' movement is similar to river water flowing around a smooth rock," Schurig said.
Moreover, the observed physical behavior of the cloak proved to be in "remarkable agreement" with that expected based on a simulated cloak, the researchers said.
Although the new cloak demonstrates the feasibility of the researchers' design, the findings nevertheless represent a "baby step" on the road to actual applications for invisibility, said team member Steven Cummer, a professor of electrical and computer engineering at Duke.
研究人员说，他们计划致力于开发三维斗篷，并进一步完善披风效果。
研究人员说，尽管适用于新的微波斗篷的相同原理可能最终导致披风的产生，从而在可见的频率范围内赋予隐形性，但这种情况仍然不确定。
"It's not yet clear that you're going to get the invisibility that everyone thinks about with Harry Potter's cloak or the Star Trek cloaking device," Smith said.
他说，要使一个物体在一个人的眼前消失，斗篷将不得不同时与构成光线的所有波长或颜色相互作用。该技术将需要科学家尚未设计的更复杂和微小的超材料结构。
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