</tr>
</table>
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=== Computing Far-Field Characteristics in FDTD ===
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Far fields are the asymptotic form the fields when R → ∞ or k<sub>0</sub>R >> 1. Under these assumptions, the fields propagate outward as transverse electromagnetic (TEM) waves:
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<math> \mathbf{H_{ff}} = \frac{1}{\eta_0} \hat{k} \cross \mathbf{E_{ff}} </math>
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Far fields are typically computed in the spherical coordinate system as functions of the elevation and azimuth observation angles θ and φ.
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