10/30/2023 0 Comments Far field diffraction definition![]() A comparison of the two source polarizations is shown below. To see the effect of changing to S polarization, modify the property "polarization angle" to 90 degrees from 0, see the polarization angle definition.Īfter re-running the FDTD Simulation, run the script file again. Due to the diffraction of the gaussian beam Ephi is non zero when the azimuthal angle is different than 15 degrees. Therefore we expect that at the center of the beam, Ephi is zero and this is clearly the case on the image plots above. The polarization of the original source is P polarized. The small non-zero terms are due to numerical rounding error on double precision numbers. We expect that Er should be zero because in the far field the electric field is perpendicular to the direction of propagation. Er is 15 orders of magnitude smaller than the other components. The results in spherical coordinates are the easiest to interpret. The script file performs a projection in both coordinate systems. farfieldvector3d uses a cartesian coordinate system and farfieldpolar3d uses a spherical coordinate system. The difference between farfieldvector3d and farfieldpolar3d is the coordinate system for defining the components of the electric field. All the properties of the polarization of the field can be determined from the amplitudes and phases of these components. These commands return three complex components of the electromagnetic field. We will continue to study the far-field example file described in Simple example. The concepts dealt with here can also be applied to the two-dimensional commands farfieldvector2d and farfieldpolar2d. In this section, we will focus on the script commands farfieldvector3d and farfieldpolar3d. For users interested in calculating far-field projections with MODE, these descriptions are basically still correct, although some subtle differences do exist.įor some far-field projections, it is important to calculate the vectorial components of the electric field in order to determine the polarization properties. ![]() ]: The descriptions and examples of the far-field projection calculation on this page are primarily intended for users of FDTD. This section discusses how to obtain and understand the vector field components and polarization of far-field projections.
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