EMA3D version 3
[ Up ]

EMA3D version 3 Advanced Features 

Isotropic Materials

Isotropic materials include both electrically and magnetically lossy media, characterized by electrical conductivity, permittivity, permeability, and magnetic conductivity. All of these constitutive parameters can be frequency dependent. The frequency dependence is represented by a sum of any number of first and second order rational functions. It is up to the user to determine the coefficients and the number of functions in the representation.

Anisotropic Materials

Anisotropic materials include both electrically and magnetically lossy media, characterized by electrical conductivity, permittivity, permeability, and magnetic conductivity. All of these constitutive parameters are frequency independent. Each constitutive parameter can be represented as a fully anisotropic 9 element tensor.

Material Priority

Material and geometry priority is now available allowing certain material and geometries to take precedence over others. This allows the placement of lines or surfaces of one material through a solid body of another material.

Material Coincidence

For this, material parameters are averaged so that various materials can exist at the same location without causing a problem. Such coincidence is common among structures obtained from CAD files.

Thin Wires

Several enhancements in thin wire modeling will be available:

• They can be imbedded in any kind of medium.
• The user can specify an inductance per unit length.
• The wires can be terminated in a variety of RLC circuits.
• These terminations can be both at thin wire junctions or at a termination at a surface.
• They will function with symmetry planes.

Background Media

The concept of background media refers to volumes of the problem space which are not explicitly meshed by the GUI, but are implicitly meshed in the EMA3D solver and to which material properties are assigned. Version 2.0 allows one background medium, which usually is a vacuum, but can be specified to be a lossy dielectric medium. In Version 2001, the user can specify any number of isotropic, linear, background media, and they can be of arbitrary shape. The big advantage of this is that it can greatly reduce the size of the problem files developed by the GUI, because the mesh of these volumes is not explicit and included in these files.

In addition, the user can select multiple non-linear background media. Nonlinear media in this context refers to the application of the 3-species air chemistry formalism for modeling air breakdown and ionization. An example would be to model air breakdown in the local region around an aperture, but not everywhere else in the problem space. This can greatly reduce computational time. Non-linear background media can also be used in conjunction with any materials.

Boundary Conditions

The following boundary conditions are being added:

• Low frequency operated on electric fields.
• Perfect Magnetic Conductor
• Periodic Boundary Conditions (useful for geometrically periodic structures)
• The user can apply a different boundary condition to each boundary.

Variable Mesh

Version 2.0 has uniform cell sizes in each Cartesian direction (but they can be different in each direction). In Version 3, the user can independently vary the cell size in each direction.

Negative Indices

In Version 2.0 the finite difference indices extended from 1 to some specified number. Extending the boundaries out beyond the designated range required redoing the lattice to extend from 1 to a different number and then remeshing. With the use of negative indices one just has to change the values in the input files.

Lossy Surfaces

The present lossy surface algorithm, which can be used to model carbon fiber composite skins or ITO (indium-tin-oxide) shielding materials, for example, is a unidirectional model, allowing energy to pass only from the unshielded side to the shielded side. In Version 3, the formalism will be bi-directional.

Two Dimensions

A two dimensional geometry is now possible involving any two of the cartesian coordinate axes.

Thin Gaps

Thin gaps can contain any materials including air designated as nonlinear and can be as thick as a cell.

Plane Wave Sources

Plane wave sources incident upon a ground plane can have any orientation with the ground plane perpendicular to any coordinate axis.

Nodal Sources

Nodal sources such as electric or magnetic current densities or electric and magnetic fields can exist within any material or background.

Gamma Sources

Gamma sources can be implemented with any material.

Probes

In addition to the probe format of EMA3D Version 2.0 several other capabilities have been included. These capabilities are described below.

New Probe

The New Probe allows the user to write out individual field components (electric or magnetic), thin wire currents, or thin gap voltages in the typical;

time, quantity1, quantity2, quantity3, ... etc.

format easily recognizable and used by a variety of plotting packages.

Bulk Current Probe

A bulk current probe allows the user to record bulk current values through or on structures of extended geometry. The user can obtain many bulk current values at different locations along or through various structure or materials of interest. The output format is as above for the New Probe.

Picture Probe

This capability allows the user to create dynamic pictures of the electromagnetic behavior of the structure being modeled. The pictures are of postscript format and are created at user specified times during the finite difference calculation. The pictures can be submitted to any postscript printer. This allows the user to easily monitor and understand the model behavior while the numerical code is still executing. The picture probes are specified using keywords in the input file. This ability allows the user to create pictures without having to create numerous amounts of nodes in the CADfix GUI which can at times be quite tedious. One has the choice of creating any number of pictures including time snapshots or maximum peak values. One can monitor normal electric fields, normal magnetic fields, electric surface current densities, or magnetic surface current densities. A descriptive legend is provided with each picture. One has the capability of controlling many parameters including:

• Page orientation
• Shading type (color or black/white)
• Scaling - linear or logarithmic
• Scaling to a specified maximum
• Observer distance from the object
• Superimposed arrows specifying vector directions
• The presence of meshlines - usually recommended, or
• Cutaway regions allowing the observation of hidden structures

Slice Probe

The slice probe creates dynamic pictures of the electromagnetic behavior on slices through the finite difference problem space. One can record the behavior of many electromagnetic quantities on these slices including normal electric fields, normal magnetic fields, tangential electric fields, or tangential magnetic fields. As with the Picture Probe above, one can create any number of pictures including time snapshots or maximum peak values which can be submitted to a postscript printer while the numerical code is still executing. This is done with the use of keywords in the input file. Thereby eliminating the need to create numerous nodes in the CADfix GUI. One may also specify materials or structures to be included in the picture for better understanding or interpretation of results. A descriptive legend is provided with each picture. One has the capability of controlling many parameters including:

• Page orientation
• Shading type (color or black/white)
• Scaling - linear or logarithmic
• Scaling to a specified maximum
• Observer distance from the slice
• Superimposed arrows specifying vector directions
• The presence of meshlines on the slices
• Cutaway regions allowing the observation of hidden areas
• The color of any included materials, or
• The presence of mesh lines on any included materials

Structure Probe

The structure probe allows one to create postscript files of the structure being modeled. One has the ability to specify what material or structures are desired and the corresponding color. Like the picture and slice probes, one has the ability of controlling many parameters including:

• Page orientation
• Shading type (color or black/white)
• Observer distance from the object
• The presence of meshlines - usually recommend, or
• Cutaway regions allowing the view of hidden structures

Fine Structure Probe

The fine structure probe creates a text file displaying the material or geometry at each field component location. This is useful if one wants a detailed understanding of the structure being modeled.

Email Webmaster

Copyright Electro Magnetic Applications, Inc. 2002-2006.
All Rights Reserved.