SENSITIVITY OF TRANSFORMATION CLOAK IN ENGINEERING

The sensitivity of cylindrical and spherical transformation cloak to several factors has been carefully studied in this paper. We find that the performance of the transformation cloak is quite sensitive to the crevice in the shell. When an obstacle is not completely wrapped inside the cloaking shell, noticeable scattering will be induced outside. It is also shown that if the shape of the cloak is changed in certain ways while the material parameters remain the same, the backward scattering is still zero. In addition, the combination of parts of cylindrical cloak can only achieve perfect invisibility in one direction, while combining the cylindrical cloak with two halves of spherical cloak can still make a perfect 3-dimensional (3D) invisible cloak. The findings are verified with finite element based simulations as well as theoretical calculations. Our discussion results are valuable to the implementation of cloak in engineering.