A HIGH-RESOLUTION INTERPOLATION AT ARBITRARY INTERFACES FOR THE FDTD METHOD

In recent years, the finite-difference time-domain (FDTD) method has f ound numerous applications in the field of computational electromagnet ics. One of the strengths of the method is the fact that no elaborate grid generation specifying the content of the problem is necessary-the medium is specified by assigning parameters to the regularly spaced c ubes. However, this can be a weakness, especially when the interfaces between neighboring media are curved or ''sloped'' and do not exactly fit the cubic lattice. Since the E- and H-fields are only calculated a t the regular intervals, sharp field discontinuities at the interfaces are often missed. Furthermore, the averaging of the material properti es often leads to significant errors. In this paper, a post-processing method is presented, which approximates the correct held behavior at the interfaces by interpolating between the FDTD calculated values, sp litting them into the components normal and tangential to the interfac es, and then enforcing the interface conditions for each of these comp onents separately.