FDTD Study on the Invisibility Performance of Two-Dimensional Cylindrical Cloak With Off-Plane Incidence

In this paper, we derive a theory for the modeling of 3-D cylindrical cloak based on 2-D finite-difference time-domain method, which is less time consuming and memory saving. By using the method, we develop the concept of invisibility angle and investigate the invisibility performance of the 3-D cylindrical cloak with 2-D constitutive parameters under off-plane incident waves. The bistatic radar cross sections as well as the scattered fields are calculated to evaluate the scatterings, from which the invisibility performance is observed to get worse with the increase in the incident angle, while the defined invisibility angle diminishes with the decrease in the cloak thickness and wavelength. The deterioration of the invisibility performance is mainly caused by the scatterings of TM wave defined in the study. The present results point out a possible way to evaluate the 2-D cloak on 3-D applications.