Broadband Ground-Plane Cloak
R. Liu,1*
C. Ji,2*
J. J. Mock,1
J. Y. Chin,3
T. J. Cui,3
D. R. Smith1
The possibility of cloaking an object from detection by electromagnetic
waves has recently become a topic of considerable interest.
The design of a cloak uses transformation optics, in which a
conformal coordinate transformation is applied to Maxwell's
equations to obtain a spatially distributed set of constitutive
parameters that define the cloak. Here, we present an experimental
realization of a cloak design that conceals a perturbation on
a flat conducting plane, under which an object can be hidden.
To match the complex spatial distribution of the required constitutive
parameters, we constructed a metamaterial consisting of thousands
of elements, the geometry of each element determined by an automated
design process. The ground-plane cloak can be realized with
the use of nonresonant metamaterial elements, resulting in a
structure having a broad operational bandwidth (covering the
range of 13 to 16 gigahertz in our experiment) and exhibiting
extremely low loss. Our experimental results indicate that this
type of cloak should scale well toward optical wavelengths.
2 Department of Statistical Science, Duke University, Durham, NC 27708, USA.
3 State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: tjcui{at}seu.edu.cn (T.J.C.); drsmith{at}duke.edu (D.R.S.)
