The FDTD Simulation For The Performance Of Dispersive Cloak Devices

The basic mathematical theory tool for electromagnetic cloak is transform optics.When designing various cloak devices,the most commonly used numerical simulation method is the time domain finite difference(FDTD)method.So far,most of electromagnetic cloak theory have been carried out in the frequency domain,focusing only on the single frequency problem,and the effect of dispersion has not been studied in depth.Therefore,establishing a reliable time domain cloak mathematical models,studying multi-frequency problems and dispersion performance,play a very important role in simulating and constructing cloak devices.In this paper,the time domain electromagnetic cloak model and FDTD algorithm,the adding wave method of TFSF,and the UPML absorbing boundary condition are introduced.We defined the scattering energy intensity based on the Poynting vector by the complex trapezoidal formula to quantitatively study the cloak effect of electromagnetic waves through four kinds of cloak materials,including perfect cloak material,layered perfect cloak material,non-magnetic cloak material and layered non-magnetic cloak material in the time domain.The effective working frequency bands of four kinds of cloak materials are obtained.The cloak performance of four cloak materials under different incident angles is compared.The reasonable number of layers of the corresponding layered cloak device is discussed under the effective working frequency band.To the best of our knowledge,this is the first time to use the time domain method to quantitatively study the effective working frequency band and the scattering energy intensity of cloak materials.