3D output data, on the other hand, are defined as functions of the space coordinates and are usually of vectorial nature. Cartesian-type and mesh-type data such as current distributions and near-field field distributions are expressed as functions of the Cartesian (X, Y, Z) coordinates. Spherical-type data like far-field radiation patterns and RCS are expressed as functions of the spherical angles (θ, φ). The 3D radiation patterns are written into a file with a "'''.RAD'''" extension. This file contains the complex values of the θ- and φ-components of the far-zone electric field (E<sub>θ</sub> and E<sub>φ</sub>) as well as the total far field magnitude as functions of the spherical observation angles θ and φ. The 3D RCS patterns are written into a file with a "'''.RCS'''" extension. This file contains the real values of the θ- and φ-polarized RCS values as well as the total RCS as functions of the spherical observation angles θ and φ. The current distributions are written into data files with a "'''.CUR'''" extension. They contain the real and imaginary parts of the X, Y and Z components of electric ('''J''') and magnetic ('''M''') current on each cells together with the definition of all the node coordinates and node indices of the cells. The near-field distributions are written into data files with a "'''.SEN'''" extension. They contain the amplitude and phase of the X, Y and Z components of electric ('''E''') and magnetic ('''H''') fields as functions of the coordinates of sampling points. All the 3D data files are listed in the '''3D Data Files''' tab of [[EM.Cube]]'s '''Data Manager'''. You can view the contents of these data files by selecting their row in the data manager and clicking the '''View''' button of the dialog.
[[Image:PMOM130.png|thumb|400px|Changing the graph type by editing a data file's properties.]]
[[Image:PMOM134.png|thumb|400px|The S<sub>11</sub> parameter plotted on a Smith Chart graph in EM.Grid.]]
=== Examining Port Characteristics ===
In particular, it may be useful to plot the S<sub>ii</sub> [[parameters]] on a Smith chart. To change the format of a data plot, select it in the Data Manager and click its '''Edit''' button. In the Edit File Dialog, choose one of the options provided in the dropdown list labeled '''Graph Type'''.
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[[File:PMOM130.png]]
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Figure 3: Changing the graph type by editing a data file's properties.
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[[File:PMOM134.png|800px]]
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Figure 4: The S<sub>11</sub> parameter plotted on a Smith Chart graph in EM.Grid.
=== Rational Interpolation Of Scattering Parameters ===