EMPro is a three-dimensional full wave electromagnetic solver based on the FDTD and FEM method. Since 1994, Agilent Technologies has provided powerful yet affordable electromagnetic simulation software to academia, industry, and government users. While EMPro has its roots in the simulation of cellular telephones, current uses for the software have reached markets as diverse as chemistry, optics, ground-penetrating radar, and biomedical devices, in addition to wireless, microwave circuit, and radar scattering applications.
EMPro provides users a great deal of freedom and functionality while creating their projects. Consequently, there are multiple ways to set up a project and run simulations. This section provides a general overview of the process of creating a project. The following figure displays the EMPro interface.
Components of a Project Tree
An EMPro project begins with the creation of a physical geometry. Geometric modeling takes place within the Geometry Tools dialog box of the Geometry workspace window. Here, objects can be created from scratch or imported from external files. The Specify Orientation tab within Modify dialog box provides exceptional functionality for situating physical parts in the simulation space.
The next illustration shows the location of the Geometry Tools dialog box.
Material definitions are created as Definition objects in the Material Editor and stored in the Project Tree so that they can be easily applied to geometry objects by drag-and-drop.
The figure below shows the location of EMPro project Definitions.
Circuit Component Definitions
After geometry objects are created and given valid material definitions, discrete circuit components may be added within the Component Tools dialog of the Geometry workspace window. Circuit component definitions are created within the Circuit Component Definition Editor and stored as Definition objects in the Project Tree. A definition can then be applied easily to the appropriate components by drag-and-drop.
In addition to discrete sources, external excitation sources can be added within the External Excitation Editor. Governing waveform definitions are created in the Waveform Editor as Definition objects within the Project Tree, and are applied by drag-and-drop to objects that require waveform definitions.
The following illustration shows the location of EMPro project Circuit Components and External Excitations.
Next, the grid (which provides the "blueprint" for the meshing operation) is defined within the Grid Tools dialog. This dialog is accessed within the Geometry workspace window or by double-clicking on the Grid icon in the Project Tree. General characteristics such as limits and cell, bounding box and padding sizes are defined in this dialog box. Additionally, customized regions may be defined by adding fixed points and grid regions so that more important regions of the project can be meshed more finely, while less-important regions can be meshed with larger cells. Object-specific grid definitions may be applied within the Gridding Properties Editor. This editor provides options for adding fixed points and grid regions to specific objects based on its characteristics, which in some cases may be more convenient than defining them in within the general grid definitions provided in the Grid Tools dialog.
The location of EMPro project Grid Tools and Gridding Properties Editor is shown in the following figure:
Meshing the Project
Once the grid is defined, the project can be meshed. During the meshing operation, materials are applied to the appropriate cell edges. Meshing occurs automatically in EMPro as soon as the project is viewed within Mesh View. Subsequent meshes are generated by manually pressing the Remesh Now button or by selecting the Automatic Remeshing feature, which will generate a mesh after every change to the geometry is made. Both of these options are found within View Tools along the right-side of the Geometry workspace window. Meshing considerations such as Meshing Property and Type (magnetic or electrical) may be specified in the Meshing Properties Editor, or by right-clicking on a specific Parts object in the Project Tree.
The location of the meshing options dialog is shown below.
Defining Outer Boundary Conditions
Outer Boundary conditions, which regulate how the calculation engine treats the boundaries of the project, are specified within the Outer Boundary Editor. This editor is accessed by double-clicking on the corresponding branch in the Project Tree.
The following shows the branch where you can access the Outer Boundary Editor.
Adding Sensor Objects
Once you define various components of the project, Sensor objects can be added. Sensors are simply objects that request data. There are several different types of sensors based on what type of data they retrieve. They can be added from the Project Tree, or within the Sensor Tools dialog in the Geometry workspace window.
The two locations from which you can add Sensor objects is shown in the next illustration.
Using the Simulations Workspace
Calculation criteria are specified within the Simulations workspace window once sensors have been added to retrieve all desired results. Here, specifications such as source type, parameter sweep definitions, S-parameter feeds, frequencies of interest, total/scattered field interfaces, and termination criteria are defined for each simulation that will be run by the calculation engine, CalcFDTD.
After running the calculation, view the results from the Results workspace window.
The illustration below shows the location of the Simulations and Results workspace windows.