In [[EM.Tempo]], a physical structure consists of sets of objects that are grouped together and identified by their material types. All the objects belonging to the same material group share the same color and same material properties. Materials are divided into seven categories that are listed under the '''Physical Structure''' node at the top of the navigation tree:
* [[FDTD_Material_Types#Perfect ConductorsPerfect_Conductors|Perfect Electric Conductor (PEC) Objects]]* [[FDTD_Material_Types#Perfect ConductorsPerfect_Conductors|Perfect Magnetic Conductor (PMC) Planes]]* [[FDTD_Material_Types#Dielectric MaterialsDielectric_Materials|Dielectric Materials]]* [[FDTD_Material_Types#Anisotropic MaterialsAnisotropic_Materials|Anisotropic Materials]]* [[FDTD_Material_Types#Dispersive MaterialsDispersive_Materials|Dispersive Materials]]
* Inhomogeneous Materials
* Thin Wires