A class of analytical absorbing boundary conditions originating from the exact surface impedance boundary condition

A new class of analytical absorbing boundary conditions (ABCs) for the truncation of the finite-difference timedomain (FDTD) lattice is introduced. These ABC originate from the exact impedance boundary operator and contain both electric and magnetic fields. The performance of the proposed second-order ABCs is studied with a twodimensional FDTD program. The results indicate that the proposed ABCs work approximately as well as the thirdorder analytical ABCs, even if they are essentially as easy to implement as the second-order Mur ABC. Also, in this paper, the relation between the so-called Engquist-Majda operator for the absorption of plane waves and the exact surface impedance boundary condition is discussed.