Perfectly Matched Layers Backed with the First Order Impedance Boundary Condition for the Time-Domain Finite-Element Method

The first order impedance boundary condition (the first order ABC) is implemented to terminate the perfectly matched layers (PMLs) in the time-domain finite-element (TDFE) simulation of electromagnetic problems. The formulation is validated by the numerical simulation of three-domain waveguide problem. The numerical results show clearly that the PMLs backed with the first order impedance boundary condition can effectively absorb the propagating wave. In the same PMLs situation, PMLs terminated by the first order impedance boundary condition can reduce about 10dB of the reflection errors compared with the PMLs terminated by PEC wall; hence, it can reduce the number of the unknowns and provide an effective mesh truncation for the TDFEM solution of wave propagation problems.