in order to implement 1D FDTD without error we should consider Perfect magnetic conductor(PMC) at the beginning of the grid and perfect electric conductor (PEC) at the end of the grid.but according to perfect boundary conditions, the refractive indices at both ends must be same. is it possible to have both PEC and PMC of same ref. index?
If PEC or PMC is used at both grid ends, then total reflection will occur. In order to simulate infinite space, an absorbing boundary condition should be implemented (Mur's, PML, etc). These always produce a relatively small amount of artificial reflections. Within the computational domain (inner nodes, homogeneous material), 1D FDTD is exact when the maximum time step is applied.
If PEC or PMC is used at both grid ends, then total reflection will occur. In order to simulate infinite space, an absorbing boundary condition should be implemented (Mur's, PML, etc). These always produce a relatively small amount of artificial reflections. Within the computational domain (inner nodes, homogeneous material), 1D FDTD is exact when the maximum time step is applied.
With PEC and PMC at the boundaries it does not matter.
Often in 1D FDTD, people use a perfectly transparent boundary condition. This does require the refractive index to be the same because there is a critical timing condition to get right for the simple BC to work.
just implement an impedance relationship
between H and E field components at both ends.
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