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<td> [[Image:FDTD_FF4.png|thumb|400px320px|A lumped source defined on a vertical PEC line object and a waveguide source defined across a hollow PEC box.]] </td><td> [[Image:FDTD_FF5.png|thumb|400px350px|A plane wave box enveloping a PEC sphere.]] </td>
</tr>
</table>