===Periodic FDTD Simulation Types===
[[FileImage:FDTD143.png|thumb|200px250px|[ [EM.Tempo]]'s R/T Macromodel Settings Dialog.]][[Image:FDTD144.png|thumb|250px| [[EM.Tempo]]'s Dispersion Sweep Settings dialog.]]Besides analyzing a periodic structure in a single-run simulationand other standard type sweeps, [[EM.Tempo]]'s offers a number of specialized sweep simulations for periodic structures. These include '''Frequency R/T Macromodel Sweep''', '''Angular Sweep''', '''R/T Macromodel Dispersion Sweep '''and '''Dispersion Huygens Sweep'''. These options are available from the '''Simulation Mode''' dropdown list of the [[FDTD ModuleEM.Tempo]]'s '''Run Dialog'''. Of these, frequency sweep and angular sweep are similar to the non-periodic case as discussed earlier. Keep in mind that in this release of [[EM.Cube]]'s [[FDTD Module]], for oblique plane wave incidences, you need to run a frequency sweep to get wideband reflection/transmission coefficient data. Similarly, you need to run an angular sweep to plot R/T coefficients vs. the incident angle. [[File:FDTD144.png|thumb|200px|[[FDTD Module]]'s Dispersion Sweep Settings dialog.]]
The '''R/T Macromodel Sweep''' option of the Simulation Mode dropdown list is only available for periodic structures. It is used to generate a lookup table model for the reflection and transmission coefficients of a periodic surface for both TM and TE polarizations. The results are written into a file named "PW_UserDefinedMacroData.mat". Through the Macromodel Settings dialog you can set the start and end value and number of samples for both the Theta (θ) and Phi (φ) angles of the incident plane wave. The R/T macormodels can be used by [[EM.Cube]]'s [[Propagation Module]] to calculate the reflection and transmission coefficients of incident rays at the facets of obstructing blocks with "non-standard" periodic surfaces.