===Modeling Planar Structures of Infinite Extents===
[[Image:FDTD23.png|thumb|300px|Domain Settings dialog]]
You can use EM.Tempo to model planar structures of infinite extents. A planar substrate usually consists of one or more dielectric layers, possibly with a PEC ground plane at its bottom. To model a laterally infinite dielectric substrate, you must assign a PML boundary condition to the four lateral sides of the domain box and set the lateral domain offset values along the ±X and ±Y directions all equal to zero. If the planar structure ends in an infinite dielectric half-space from the bottom, you must assign a PML boundary condition to the bottom side of the domain box and set the -Z offset equal to zero. This leaves only the +Z offset with a nonzero value.
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<td> [[Image:FDTD22(1).png|thumb|300px|The computational domain box of a metallic sphere with nonzero offset in all directions.]] </td>
<td> [[Image:FDTD24.png|thumb|300px400px|The computational domain box of a laterally infinite planar structure with a PEC ground and zero ±X and ±Y and -Z domain offsets.]] </td>
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