SUMMARY
According to the rapidly growing use of finite difference time domain method (FDTD) in numerical electromagnetic, this technique can be used to solve problems involving complex permittivity such as a dispersive materials. Since the dielectric constant for such media vary with frequency. In this paper we simulate and study the electromagnetic waves with different frequencies through Debye medium using (FDTD) method, Debye model describes a single pole frequency dependence. The results shows a simulation of a pulse going into frequency dependent dielectric material. Also we evaluate electric field,magnetic field and power density in dispersive medium with different frequencies. Noticed that at higher relative dielectric constant with lower frequency produced smaller amplitude, and the amplitude attenuated rapidly at high frequency. It is the most widely used time domain numerical method largely due to the simplicity of the solution algorithm.