If your computer has an Intel CPU, then [[EM.Cube]] offers special versions of all the above linear solvers that have been optimized for Intel CPU platforms. These optimal solvers usually work 2-3 time faster than their generic counterparts. When you install [[EM.Cube]], the option to use Intel-optimized solvers is already enabled. However, you can disable this option (e.g. if your computer has a non-Intel CPU). To do that, open the [[EM.Cube]]'s Preferences Dialog from '''Menu > Edit > Preferences''' or using the keyboard shortcut '''Ctrl+H'''. Select the Advanced tab of the dialog and uncheck the box labeled "''' Use Optimized Solvers for Intel CPU'''".
[[File:PMOM82.png]]
[[Image:PMOM127.png|thumb|400px|Settings adaptive frequency sweep parameters in EM.Picasso's Frequency Settings Dialog.]]=== Running Uniform and Adaptive Frequency Sweeps Sweep Simulations in EM.Picasso ===
[[Image:PMOM127.png|thumb|400px|EM.Picasso's Frequency Settings Dialog.]]In a frequency sweepsimulation, the operating frequency of a planar structure the project is varied during the simulation, and the frequency response of your structure is computed at each sweep runfrequency sample. [[EM.Cube]]'s [[Planar ModuleLibera]] offers two types of frequency sweep: Uniform uniform and Adaptiveadaptive. In a uniform frequency sweep, the equally spaced frequency range samples are generated between the start and end frequencies. In the number 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 specifiedcalculated and inserted in a progressive manner. The At each iteration, the frequency samples are equally spaced used to calculate a rational approximation of the scattering parameter response over the specified frequency range. At The process stops when the end of each individual 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 rundata points. This usually captures frequency response characteristics such as resonances with much fewer calculated data points. However, you have to make sure that the output data are collected and storedprocess converges. At 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 3D data can be visualized '''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 animated'''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 2D data can be graphed in EM.Gridnumber of frequency samples.
To run During a uniform frequency sweep, open as the '''Simulation Run Dialog''', and select the '''Frequency Sweep''' option from the dropdown list labeled '''Simulation Mode'''. When you choose the frequency sweep option, the '''Settings''' button next to the simulation mode dropdown list becomes enabled. Clicking this button opens the '''Frequency Settings''' dialog. The '''Frequency Range'''is initially set equal to your project's center frequency minus and plus half bandwidth. But you can change changes, so does the values of '''Start Frequency'''and '''End Frequency''' as well as the '''Number of Samples'''wavelength. The dialog offers two options for '''Frequency Sweep Type''': '''Uniform''' or '''Adaptive'''. Select the former type. It is very important to note that in As a MoM simulationresult, changing the frequency results in a change of the mesh of the structure, too. This is because the mesh density is defined in terms of the number of cells per effective wavelength. By default, during a frequency sweep, [[EM.Cube]] fixes the mesh density also changes at the highest each frequency, isample.e., at the "End Frequency". This usually results in a smoother The frequency response. You have the option to fix settings dialog gives you three choices regarding the mesh at the center frequency of the project or let [[EM.Cube]] "remesh" the planar structure at each frequency sample during a frequency sweep. You can make one of these three choices using the radio button in the '''Mesh Settings''' section of the dialog. Closing the Frequency Settings dialog returns you to the Simulation Run dialog, where you can start the planar MoM frequency sweep simulation by clicking the '''Run''' button.:
Frequency sweeps are often performed to study * Fix mesh at the highest frequency response of a planar structure. In particular, * Fix mesh at the variation of scattering [[parameters]] like S<sub>11</sub> (return loss) and S<sub>21</sub> (insertion loss) with center frequency are of utmost interest. When analyzing resonant structures like patch antennas or planar filters over large frequency ranges, you may have to sweep a large number of frequency samples to capture their behavior with adequate details. The resonant peaks or notches are often missed due to the lack of enough resolution. [[EM.Cube]]'s [[Planar Module]] offers a powerful adaptive frequency sweep option for this purpose. It is based on the fact that the frequency response of a physical, causal, multiport network can be represented mathematically using a rational function approximation. In other words, the S [[parameters]] of a circuit exhibit a finite number of poles and zeros over a given frequency range. [[EM.Cube]] first starts with very few frequency samples and tries to fit rational functions of low orders to the scattering [[parameters]]. Then, it increases the number of samples gradually by inserting intermediate frequency samples in a progressive manner. At each iteration cycle, all the possible rational functions of higher orders are tried out. The process continues until adding new intermediate frequency samples does not improve the resolution of the "S<sub>ij</sub>" curves over the given frequency range. In that case, the curves are considered as having converged. You must have defined one or more ports for your planar structure run an adaptive frequency sweep. Open the Frequency Settings dialog from the Simulation Run dialog and select the '''Adaptive''' option of '''Frequency Sweep Type'''. You have to set values for '''Minimum Number of Samples''' and '''Maximum Number of Samples'''. Their default values are 3 and 9, respectively. You also set a value for the '''Convergence Criterion''', which has a default value of 0.1. At * Re-mesh at each iteration cycle, all the S [[parameters]] are calculated at the newly inserted frequency samples, and their average deviation from the curves of the last cycle is measured as an error. When this error falls below the specified convergence criterion, the iteration is ended. If [[EM.Cube]] reaches the specified maximum number of iterations and the convergence criterion has not yet been met, the program will ask you whether to continue the process or exit it and stop.
{{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.}}