Research On Absorbing Boundary Condition Based On FDTD

The traditional absorbing boundary conditions,such as Mur and perfect match layer(PML),are very mature.But the effect of Mur can not meet the high accuracy of the simulation requirements.Although the effect of PML absorption is very good,but it needs more truncated cells,more storage space and computational memory than those of Mur needs.The principle of equivalence is the basic theory of electromagnetic field.Based on this theory,equivalent electric and magnetic fields with the outgoing wave can be produced around the FDTD simulation domain.this can be used as segmentation between the scattered field and the total field and can also be combined with the higden operator as an absorbing boundary condition.The Huygens absorbing boundary is an absorbing boundary condition based on equivalence principle.A spatio-temporal interpolation operator with correction factor has been proposed.The operator can eliminate one order and two order expansion in the two order Taylor formula,can more accurately estimate the Huygens equivalent field value.Then we realize the Huygens surface absorbing boundary in two dimensional FDTD algorithm,and combine Huygens surface with Mur absorption boundary to get a mixed absorbing boundary.Experimental simulation and numerical analysis show that,Huygens surface greatly improves the performance of Mur at cost of small increase in computational complexity.Compared with the absorption effect of PML,when achieving the same absorption effect,the number of truncated cells is relatively less.At the same time the Huygens surface has mature theory,simple programming,less computing memory etc.,and can be conveniently inserted into FDTD computational domain.so the application of Huygens surface in FDTD is worthy of attention.