Electromagnetic metamaterials are a new type of artificial composite electromagnetic material whose dielectric constant and magnetic permeability can be artificially controlled, and various parameters can be positive or negative. Electromagnetic metamaterials can be applied due to their unique electromagnetic properties
Electromagnetic wave absorbing materialsRealize stealth waves for metal targets. For example, by utilizing the negative electromagnetic parameters of the material to construct a high impedance surface, a thin plate electromagnetic wave absorbing structure can be achieved; For example, by utilizing the electromagnetic resonance structure in the material, controllable design of its electromagnetic parameters can be achieved for specific frequency bands. The absorption performance of electromagnetic metamaterials is mainly determined by the unit resonance structure, so effective adjustment of the absorption spectrum can be easily achieved by manually changing the resonance structure. For example, integrating adjustable devices such as varactor diodes into absorbing structures can produce absorbing structures with novel and adjustable functions. The material thickness is only one twentieth of the wavelength, and so on. Especially by utilizing the strong resonance loss property of electromagnetic metamaterials, by designing the electromagnetic parameters of metamaterials reasonably, their wave impedance can be matched with air, and the resonance loss of electromagnetic specific materials can be used to achieve complete absorption. The absorbing structure designed and prepared based on this can theoretically achieve 100% absorption, and the microwave absorption rate has reached 88% in experiments. Due to the ideal absorption characteristics of electromagnetic metamaterials only in a narrow frequency band, the absorbing structure composed of metamaterials is a narrowband absorbing structure. This narrowband absorbing structure can be used to solve the low-frequency problem of absorbing materials, shield or absorb signals in specific communication or radar detection frequency bands, and is suitable for applications such as stealth for specific frequency radars, specific radar cover structures, electromagnetic interference resistance, and information security. By designing the electromagnetic parameters of electromagnetic metamaterials reasonably, the incident electromagnetic waves can be completely diffracted and propagated in the artificial electromagnetic metamaterial covering the target, thereby achieving complete invisibility of the target. The new concept of electromagnetic wave bending diffraction propagation has been fully validated experimentally, achieving stealth of metal targets in the microwave frequency range. The new concept of electromagnetic wave stealth theory and experimental verification based on new artificial electromagnetic materials has once again been rated as one of the top ten technological breakthroughs in 2006 by the American journal Science. This new concept of stealth technology is different from the concept of using absorbing materials to achieve stealth. It does not absorb radar wave energy through materials, but designs specific artificial electromagnetic materials to make radar waves bypass weapon targets without generating echoes.
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