Equivalence theorem boundary conditions for FDTD formulations

A boundary condition for the truncation of the grid in finite-difference time-domain (FDTD) formulations is presented. The proposed technique restricts the computational domain by truncating the FDTD grid close to the scattering objects. By using the equivalence theorem, the proposed procedure yields a coupling between the region outside the boundary (exterior problem) and inside the boundary (interior problem). A resulting hybrid FDTD-method of moments technique is used to obtain a numerical solution of the coupled problems. Numerical applications demonstrate the validity of the proposed procedure.