If you run a simulation without having defined any observables, no data will be generated at the end of the simulation. An analysis is a single-run simulation. In multi-run simulation modes, certain [[parameters]] are varied and a collection of simulation data are generated. At the end of a multi-run simulation, you can graph the simulation results in EM.Grid or you can animate the 3D simulation data from the navigation tree.
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=== Running A Planar MoM Analysis ===
To run a planar MoM analysis of your project structure, open the Run Simulation Dialog by clicking the '''Run''' [[File:run_icon.png]] button on the '''Simulate Toolbar''' or select '''Menu > Simulate > Run''' or use the keyboard shortcut {{key|Ctrl+R}}. The '''Single-Frequency Analysis''' option of the '''Simulation Mode''' dropdown list is selected by default. Once you click the {{key|Run}} button, the simulation starts. A new window called the "Output Window" opens up that reports the different stages of simulation and the percentage of the tasks completed at any time. After the simulation is successfully completed, a message pops up and reports the end of simulation. In certain cases like calculating scattering [[parameters]] of a circuit or reflection / transmission characteristics of a periodic surface, some results are also reported in the output window.
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[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Parametric_Modeling,_Sweep_%26_Optimization#Running_Frequency_Sweep_Simulations_in_EM.Cube | Uniforms and Adaptive Frequency Sweep Simulations]]'''.
=== Setting Numerical Parameters ===
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=== Running Frequency Sweep Simulations in EM.Picasso ===
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[[Image:PMOM127.png|thumb|400px|EM.Picasso's Frequency Settings Dialog.]]
In a frequency sweep simulation, the operating frequency of the project is varied during the simulation, and the frequency response of your structure is computed at each frequency sample. [[EM.Libera]] offers two types of frequency sweep: uniform and adaptive. In a uniform sweep, equally spaced frequency samples are generated between the start and end frequencies. In the case of an adaptive sweep, you must specify the '''Maximum Number of Iterations''' as well as the '''Error'''. An adaptive sweep simulation starts with a few initial frequency samples, where the Wire MoM engine is initially run. Then, the intermediate frequency samples are calculated and inserted in a progressive manner. At each iteration, the frequency samples are used to calculate a rational approximation of the scattering parameter response over the specified frequency range. The process stops when the specified error criterion is met in a mean-square sense. The adaptive sweep simulation results are always continuous and smooth. This is due to the fact that a rational function curve is fitted through the discrete frequency data points. This usually captures frequency response characteristics such as resonances with much fewer calculated data points. However, you have to make sure that the process converges. Otherwise, you might get an entirely wrong, but still perfectly smooth, curve at the end of the simulation.
To run a 3D MoM frequency sweep, open the '''Run Simulation Dialog''' and select '''Frequency Sweep''' from the '''Simulation Mode''' dropdown list in this dialog. The '''Settings''' button located next to the simulation mode dropdown list becomes enabled. If you click this button, the Frequency Settings Dialog opens up. First you have to choose the '''Sweep Type''' with two options: '''Uniforms''' or '''Adaptive'''. The default option is a uniform sweep. In the frequency settings dialog, you can set the start and end frequencies as well as the number of frequency samples.
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During a frequency sweep, as the project's frequency changes, so does the wavelength. As a result, the mesh of the structure also changes at each frequency sample. The frequency settings dialog gives you three choices regarding the mesh of the project structure during a frequency sweep:
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* Fix mesh at the highest frequency.
* Fix mesh at the center frequency.
* Re-mesh at each frequency.
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{{Note|For large frequency ranges, you may have to increase both the minimum and maximum number of samples. Moreover, remeshing the planar structure at each frequency may prove more practical than fixing the mesh at the highest frequency.}}
== Working with EM.Picasso Simulation Data ==