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EM.Picasso

2,239 bytes removed, 03:53, 13 August 2015

/* Working with EM.Picasso Simulation Data */

* '''Current Distributions''': Electric and magnetic current amplitude and phase on all metal and slot traces and embedded objects

* '''Near-Field Distributions''': Electric and magnetic field amplitude and phase on specified planes and their central axes

~~=== Examining Port Characteristics ===~~

If your planar structure is excited by gap sources or probe sources or de-embedded sources, and one or more ports have been defined, the planar MoM engine calculates the scattering, impedance and admittance (S/Z/Y) [[parameters]] of the designated ports. The scattering [[parameters]] are defined based on the port impedances specified in the project's Port Definition dialog. If more than one port has been defined in the project, the S/Z/Y matrices of the multiport network are calculated.

At the end of a planar MoM simulation, the values of S/Z/Y [[parameters]] and VSWR data are calculated and reported in the output message window. The S, Z and Y [[parameters]] are written into output ASCII data files of complex type with a "'''.CPX'''" extension. Every file begins with a header consisting of a few comment lines that start with the "#" symbol. The complex values are arranged into two columns for the real and imaginary parts. In the case of multiport structures, every single element of the S/Z/Y matrices is written into a separate complex data file. For example, you will have data files like S11.CPX, S21.CPX, ..., Z11.CPX, Z21.CPX, etc. The VSWR data are saved to an ASCII data file of real type with a "'''.DAT'''" extension called, VSWR.DAT. If you run an analysis, the port characteristics have single complex values, which you can view using [[EM.Cube]]'s data manager. However, there are no curves to graph. You can plot the S/Z/Y [[parameters]] and VSWR data when you have data sets, which are generated at the end of any type of sweep including a frequency sweep. In that case, the ".CPX" files have multiple rows corresponding to each value of the sweep parameter (e.g. frequency). [[EM.Cube]]'s 2D graph data are plotted in EM.Grid, a versatile graphing utility. You can plot the port characteristics directly from the Navigation Tree. Right click on the '''Port Definition''' item in the '''Observables''' section of the Navigation Tree and select one of the items: '''Plot S [[Parameters]]''', '''Plot Y [[Parameters]]''', '''Plot Z [[Parameters]]''', or '''Plot VSWR'''. In the first three cases, another sub-menu gives a list of individual port [[parameters]]. 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'''. [[Image:Info_icon.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#~~Graphing_Port_Characteristics~~ Computing_and_Graphing_Port_Characteristics | Computing and Graphing Port Characteristics]]'''.

[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#Rational_Interpolation_of_Port_Characteristics | Rational Interpolation of Scattering Parameters]]'''.

~~=== Visualizing Current Distributions ===~~

Electric and magnetic currents are the fundamental output data of a planar MoM simulation. After the numerical solution of the MoM linear system, they are found using the solution vector '''[I]''' and the definitions of the electric and magnetic vectorial basis functions:

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~~=== Visualizing the Near Fields ===~~

[[File:PMOM90.png|thumb|320px|[[Planar Module]]'s Field Sensor dialog.]] EM.Picasso allows you to visualize the near fields at a specific field sensor plane. Note that unlike [[EM.Cube]]'s other computational modules, near field calculations in EM.Picasso usually takes a significant amount of time. This is due to the fact that at the end of a planar MoM simulation, the fields are not available anywhere (as opposed to [[EM.Tempo]]), and their computation requires integration of complex dyadic Green's functions of a multilayer background structure as opposed to the free space Green's functions.

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~~=== Computing Radiation Pattern of Planar Structures ===~~

Even though EM.Picasso's MoM engine does not need a radiation box, you still have to define a "Far Field" observable for radiation pattern calculation. This is because far field calculations take time and you have to instruct [[EM.Cube]] to perform these calculations. Once a planar MoM simulation is finished, three far field items are added under the Far Field item in the Navigation Tree. These are the far field component in θ direction, the far field component in φ direction and the "Total" far field. The 2D radiation pattern graphs can be plotted from the '''Data Manager'''. A total of eight 2D radiation pattern graphs are available: 4 polar and 4 Cartesian graphs for the XY, YZ, ZX and user defined plane cuts.

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~~=== Radar Cross Section of Planar Structures ===~~

When a planar structure is excited by a plane wave source, the calculated far field data indeed represent the scattered fields of that planar structure. [[EM.Picasso]] can also calculate the radar cross section (RCS) of a planar target. Note that in this case the RCS is defined for a finite-sized target in the presence of an infinite background structure. The scattered θ and φ components of the far-zone electric field are indeed what you see in the 3D far field visualization of radiation (scattering) patterns. Instead of radiation or scattering patterns, you can instruct [[EM.Picasso]] to plot 3D visualizations of σ<sub>θ</sub>, σ<sub>φ</sub> and the total RCS.

Kazem Sabet

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