Efficient High-Order Absorbing Boundary Condition for the ADI-FDTD Method

In this letter, an efficient high-order absorbing boundary condition for the alternating-direction-implicit-finite-difference time-domain (ADI-FDTD) method is developed. The proposed high-order absorbing boundary condition (ABC) has very high numerical efficiency because it can keep the tri-diagonal matrix form during the ADI iteration. The absorbing performance of the proposed ABC is analyzed theoretically. To verify the performance of the proposed high-order ABC, a rectangular waveguide problem which has very strong dispersion characteristic is analyzed with the ADI-FDTD method. Numerical results show that the proposed high-order ABC has excellent absorbing performance.