===Far Field Calculations in FDTD===
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{{mainpage|[[Farfield Calculations in EM.Tempo]]}}
For radiating structures or scatterers, the far field quantities are of primary interest. [[EM.Cube]]'s [[FDTD Module]] can calculate the far field radiation patterns of an antenna or the radar cross section (RCS) of a target. In general, by far fields we mean the electric fields evaluated in the far zone of a physical structure, which satisfies the following condition:
In the FDTD method, the far fields are calculated using a near-field-to-far-field transformation of the field quantities on a given closed surface. [[EM.Cube]] uses rectangular boxes to define these closed surfaces. You can use [[EM.Cube]]'s default radiation box or define your own. Normally, the radiation box should enclose the entire FDTD structure. In this case, the calculated radiation pattern corresponds to the entire radiating structure. The radiation box may also contain only parts of a structure, which results in partial radiation patterns. Â Â More mathematical details pertaining to EM.Tempo's Far Field calculation are described at [[Farfield Calculations in EM.Tempo]].
===Defining The Far Field Box===