Electromagnetic cloaking, as challenging as it may be to the physicist and the engineer has become a topical subject over the past decade. Thanks to the transformations optics (TO) invisibility devices are in sight even though quite drastic limitations remain yet to be lifted. The extreme material properties which are deduced from TO can be achieved in practice using dispersive metamaterials. However, the bandwidth over which a metamaterial cloak is efficient is drastically limited. We design and simulate a spherical cloak which takes into account the dispersive nature of relative permittivity and permeability tensors realized by plasma-like metamaterials. This spherical cloak works over a broad frequency-band even though these materials are of a highly dispersive nature. We establish two equations of state that link the eigenvalues of the permittivity and permeability tensors in every spherical cloak regardless of the geometrical transformation. Frequency dispersive properties do not disrupt cloaking as long as the equations of states are satisfied in the metamaterial cloak.

电磁隐蔽对物理学家和工程师而言可能具有挑战性，在过去十年中已成为热门话题。借助这种转换，光学（TO）隐身设备就可以看到了，尽管还有很大的局限性尚待消除。从TO推导得出的极端材料特性可以在实践中使用弥散超材料实现。但是，极大地限制了超材料披风的有效带宽。我们设计并模拟了一个球形披风，该披风考虑到了类似等离子体的超材料所实现的相对介电常数和磁导率张量的分散特性。即使这些材料具有高度分散的性质，该球形斗篷仍可在很宽的频带上工作。我们建立了两个状态方程，它们链接了每个球形披风的介电常数和磁导率张量的特征值，而与几何变换无关。只要超材料披风中的状态方程满足，频率分散特性就不会破坏披风。