== Building a Planar Structure ==
[[Image:PMOM9.png|thumb|300px|EM.Picasso's Substrate Layer dialog.]]
=== Understanding the Background Structure ===
EM.Picasso is intended for constructing and modeling planar layered structures. By a planar structure we mean one that contains a background substrate of laterally infinite extents, made up of one or more material layers all stacked up vertically along the Z-axis. Objects of finite size are then interspersed among these substrate layers. The background structure in EM.Picasso is called the "'''Layer Stack-up'''". The layer stack-up is always terminated from the top and bottom by two infinite half-spaces. The terminating half-spaces might be the free space, or a perfect conductor (PEC ground), or any material medium. Most planar structures used in RF and microwave applications such as microstrip-based components have a PEC ground at their bottom. Some structures like stripline components require two bounding grounds (PEC half-spaces) both at their top and bottom.
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=== Planar Object Types ===
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EM.Picasso groups objects by their trace type and their hierarchical location in the substrate layer stack-up. All the planar objects belonging to the same trace group are located on the same substrate layer boundary and have the same color. All the embedded objects belonging to the same embedded set lie inside the same substrate layer and have the same color and same material composition.
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EM.Picasso provides the following types of objects for building a planar layered structure:
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# '''PEC Traces''': These represent infinitesimally thin metallic planar objects that are deposited or metallized on or between substrate layers. PEC objects are modeled by surface electric currents.
# '''Slot Traces''': These are used to model slots and apertures in PEC ground planes. Slot objects are always assumed to lie on an infinite horizontal PEC ground plane with zero thickness (which is not explicitly displayed in the project workspace). They are modeled by surface magnetic currents.
# '''Conductive Sheet Traces:''' These represent imperfect metals. They have a finite conductivity and a very small thickness. A surface impedance boundary condition is enforced on the surface of such traces.
# '''PEC Via Sets:''' These are metallic objects such as shorting pins, interconnect vias, plated-through holes, etc. that are grouped together as prismatic object sets. The embedded objects are modeled as vertical volume conduction currents.
# '''Embedded Dielectric Sets:''' These are prismatic dielectric objects inserted inside a substrate layer. You can define a finite permittivity and conductivity for such objects, but their height is always the same as the height of their host layer. The embedded dielectric objects are modeled as vertical volume polarization currents.
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Click here to learn more about [[Planar Traces & Object Types]].
=== Defining the Layer Stack-Up ===
You can delete a layer by selecting its row in the table and clicking the '''Delete''' button. To move a layer up and down, click on its row to select and highlight it. Then click either the '''Move Up''' or '''Move Down''' buttons consecutively to move the selected layer to the desired location in the stack-up. Note that you cannot delete or move the top or bottom half-spaces.
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=== Editing Substrate Layers ===
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After creating a substrate layer, you can always edit its properties in the Layer Stack-up Settings dialog. Click on any layer's row in the table to select and highlight it and then click the '''Edit''' button. The substrate layer dialog opens up, where you can change the layer's label and assigned color. In the material properties section of the dialog, you can change the name of the material and its properties: permittivity (e<sub>r</sub>), permeability (µ<sub>r</sub>), electric conductivity (s) and magnetic conductivity (s<sub>m</sub>). To define electrical losses, you can either assign a value for electric conductivity (s), or alternatively, define a loss tangent for the material. In the latter case, check the box labeled "'''Specify Loss Tangent'''" and enter a value for it. In this case, the electric conductivity field becomes greyed out and reflects the corresponding s value at the center frequency of the project.
You can also set the thickness of the substrate layer in the project units. Note that you cannot change the thickness of the top and bottom half-spaces. You can only change their material properties.
[[FileImage:PMOM9PMOM12.png|thumb|400px|EM.Picasso's Stack-up Settings dialog.]]=== Defining Traces & Object Sets ===
Figure 1: When you start a new project in [[Planar Module]]'s Substrate Layer dialog. === Planar Object Types === [[EM.Picasso]] groups objects by their trace type , the project workspace looks empty, and their hierarchical location in the substrate layer stack-up. All the planar objects belonging to the same trace group there are located on the same substrate layer boundary and have the same color. All the embedded no finite objects belonging to the same embedded set lie inside the same substrate layer and have the same color and same material compositionin it.  EM.Picasso provides the following types of objects for building However, a planar layered default background structure: # '''Perfect Electric Conductor (PEC) Traces:''' These represent infinitesimally thin metallic objects that are deposited or metallized on or between substrate layers. PEC objects are modeled is always present by surface electric currents that satisfy the PEC boundary conditiondefault.# '''Perfect Magnetic Conductor (PMC) Traces:''' These Objects are used to model slots and apertures in infinite PEC ground planes. PMC objects are always assumed to lie on an infinite horizontal PEC ground plane with zero thickness. They are modeled by surface magnetic currents, enforcing the continuity defined as part of tangential fields across the slots traces or aperturesembedded sets.# '''Conductive Sheet Traces:''' These represent imperfect metals. They have Once defined, you can see a finite conductivity and a very small thickness. A surface impedance boundary condition is enforced on the surface list of such traces.# '''PEC Via Sets:''' These are metallic project objects such as shorting pins, interconnect vias, plated-through holes, etc. that are grouped together as prismatic object sets. The embedded objects are modeled as vertical volume conduction currents.# in the '''Embedded Dielectric Sets:Physical Structure''' These are prismatic dielectric objects inserted inside a substrate layer. You can define a finite permittivity and conductivity for such objects, but their height is always section of the same as the height of their host layer. The embedded dielectric objects are modeled as vertical volume polarization currentsnavigation tree. === Defining Traces & Object Sets ===
When you start a new project in [[Planar Module]], the project workspace looks empty, and there are no finite objects in it. However, a default background structure is always assumed to exist by default. Objects are defined as part of traces or embedded sets. Once defined, you can see a list of project objects in the '''Physical Structure''' section of the Navigation Tree. Traces and object sets can be defined either from Layer Stack-up Settings dialog or from the Navigation Treenavigation tree.
In the '''Layer Stack-up Settings''' dialog, you can add a new trace to the stack-up by clicking the arrow symbol on the '''Insert''' button of the dialog. You have to choose from '''Metal (PEC)''', '''Slot (PMC)''' or '''Conductive Sheet''' options. A respective dialog opens up, where you can enter a label and assign a color other than default ones. Once a new trace is defined, it is added, by default, to the top of the stack-up table underneath the top half-space. From here, you can move the trace down to the desired location on the layer hierarchy.
[[File:PMOM12.png]]
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Figure 1: [[Planar Module]]'s Stack-up Settings dialog.
Every time you define a new trace, it is also added under the respective category in the Navigation Tree. Alternatively, you can define a new trace from the Navigation Tree by right clicking on one of the trace type names and selecting '''Insert New PEC Trace...'''or '''Insert New PMC Trace...'''or '''Insert New Conductive Sheet Trace...'''A respective dialog opens up for setting the trace properties. Once you close this dialog, it takes you directly to the Layer Stack-up Settings dialog so that you can set the right position of the trace on the stack-up.
[[File:PMOM13.png]]
[[EM.Cube]]'s [[Planar Module]] Picasso has a special feature that makes construction of planar structures quite easy and straightforward. '''The active work plane of the project workspace is always set at the plane of the active trace.''' In [[EM.Cube]]'s other modules, all objects are drawn in the XY plane (z = 0) by default. In [[Planar Module]], all new objects are drawn on a horizontal plane that is located at the Z-coordinate of the currently active trace. As you change the active trace or add a new trace, you will also change the active work plane. Click here to learn more about [[Planar Traces & Object Types]].
=== Planar Module's Rules & Limitations ===
You couple two or more sources using the '''Port Definition Dialog'''. To do so, you need to change the default port assignments. First, delete all the ports that are to be coupled from the Port List of the dialog. Then, define a new port by clicking the '''Add''' button of the dialog. This opens up the Add Port dialog, which consists of two tables: '''Available''' sources on the left and '''Associated''' sources on the right. A right arrow ('''-->''') button and a left arrow ('''<--''') button let you move the sources freely between these two tables. You will see in the "Available" table a list of all the sources that you deleted earlier. You may even see more available sources. Select all the sources that you want to couple and move them to the "Associated" table on the right. You can make multiple selections using the keyboard's '''Shift''' and '''Ctrl''' keys. Closing the Add Port dialog returns you to the Port Definition dialog, where you will now see the names of all the coupled sources next to the name of the newly added port.
{{Note|It is your responsibility to set up coupled ports and coupled [[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|[[Transmission Lines|transmission lines]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]] properly. For example, to excite the desirable odd mode of a coplanar waveguide (CPW), you need to create two rectangular slots parallel to and aligned with each other and place two gap sources on them with the same offsets and opposite polarities. To excite the even mode of the CPW, you use the same polarity for the two collocated gap sources. Whether you define a coupled port for the CPW or not, the right definition of sources will excite the proper mode. The couple ports are needed only for correct calculation of the port characteristics.}}
[[File:PMOM51(2).png|800px]]