Ports are used to order and index gap sources for S parameter calculation. They are defined in the '''Observables''' section of the Navigation Tree. Right click on the '''Port Definition''' item of the Navigation Tree and select '''Insert New Port Definition...''' from the contextual menu. The Port Definition Dialog opens up, showing the total number of existing sources in the workspace. By default, as many ports as the total number of sources are created. You can define any number of ports equal to or less than the total number of sources. This includes both gap sources and active lumped elements (which contain gap sources). In the '''Port Association''' section of this dialog, you can go over each one of the sources and associate them with a desired port. Note that you can associate more than one source with same given port. In this case, you will have a coupled port. All the coupled sources are listed as associated with a single port. However, you cannot associate the same source with more than one port. Finally, you can assign '''Port Impedance''' in Ohms. By default, all port impedances are 50Σ. The table titled '''Port Configuration''' lists all the ports and their associated sources and port impedances.
{{Note|In [[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|EM.CUBE]]]]]]]]]]]]]]]]]]]]]]]]]]]] you cannot assign ports to an array object, even if it contains sources on its elements. To calculate the S [[parameters]] of an antenna array, you have to construct it using individual elements, not as an array object.}}
[[File:port-definition.png]]
The wire MoM engine settings dialog.
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== More 3D MoM Simulation Types ==
=== 3D MoM Sweep Simulations ===
The radiation patterns of antenna arrays usually have a main beam and several side lobes. Some [[parameters]] of interest in such structures include the '''Half Power Beam Width (HPBW)''', '''Maximum Side Lobe Level (SLL)''' and '''First Null [[Parameters]]''' such as first null level and first null beam width. You can have [[EM.Cube|EM.CUBE]] calculate all such [[parameters]] if you check the relevant boxes in the "Additional Radiation Characteristics" section of the '''Radiation Pattern Dialog'''. These quantities are saved into ASCII data files of similar names with '''.DAT''' file extensions. In particular, you can plot such data files at the end of a sweep simulation.
{{Note|Defining an array factor in the radiation pattern dialog simply performs a post-processing calculation. The resulting far field obviously do not take into account any inter-element coupling effects as [[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|[[EM.Cube|EM.CUBE]]]]]]]]]]]]]]]]]]]]]]]]]]]] does not construct a real physical array in the project workspace.}}
{{Note|Using an array factor for far field calculation, you cannot assign non-uniform amplitude or phase distribution to the array elements. For this purpose, you have to define an array object.}}
Just like current distribution and field sensor plots, each individual 3-D radiation pattern plots has an '''Output Settings Dialog''', from which you can further customize the plot's scale (linear vs. dB), lower and upper limits and color map type.
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=== 2D Radiation Graphs ===
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At the end of a Wire MoM simulation, the radiation pattern data E<sub>θ</sub>, E<sub>φ</sub>, and E<sub>tot</sub> in the three principal XY, YZ and ZX planes as well as an additional user defined phi plane cut are available for plotting on 2-D graphs. There are a total of eight 2D pattern graphs in the data manager: 4 polar graphs and 4 Cartesian graphs of the same pattern data. To open data manager, click the '''Data Manager''' [[File:data_manager_icon.png]] button of the '''Compute Toolbar''' or select '''Compute [[File:larrow_tn.png]]Data Manager''' from the menu bar or right click on the '''Data Manager''' item of the Navigation Tree and select Open Data Manager... from the contextual menu or use the keyboard shortcut '''Ctrl+D'''. In the Data manager Dialog, you will see a list of all the data files available for plotting. These include the four polar pattern data files with a '''.ANG''' file extension and the four Cartesian pattern data file with a '''.DAT''' file extension. Select any data file by clicking and highlighting its '''ID''' in the table and then click the '''Plot''' button to plot the graph.
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At the end of a Wire MoM sweep simulation, other radiation characteristics are also computed as a function of the sweep variable (frequency, angle, or any other user defined variable). These include the '''Directivity (D0)''', '''Total Radiated Power (PRAD)''' and '''Directive Gain (DG)''' as a function of the theta and phi angles. Another radiation characteristic of interest especially in circularly polarized scenarios is the Axial Ratio. In [[EM.Cube|EM.CUBE]], the axial ratio is always defined in the LCPz or RCPz sense based on the X- and Y-components of the electric field. In order to calculate the directive gain or axial ratio, you have to check the boxes labeled '''Axial Ratio (AR)''' or '''Directive Gain (DG)''' in the "Additional Radiation Characteristics" section of the '''Radiation Pattern Dialog'''. Four 2-D Cartesian graphs of the axial ratio as functions of the theta angle a generated in the three principal XY, YZ and ZX planes as well as the additional user defined phi plane cut. At the end of a Wire MoM sweep simulation, the directive gain and axial ratio can also be plotted as functions of the sweep variable. In this case, either quantity needs to be computed at a fixed pair of phi and theta angles. These angles are specified in degrees as '''User Defined Azimuth & Elevation''' in the "Output Settings" section of the '''Radiation Pattern Dialog'''. The default values of the user defined azimuth and elevation are both zero corresponding to the zenith.
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[[File:wire_pic44.png]]
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The data manager dialog showing a list of 2-D polar and Cartesian radiation pattern graphs.
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