Material and Geometric Priority

In EMA3D®, there are algorithms present to handle coincident or overlapping materials. Such occurrences are common among objects and geometry obtained from CAD files. The algorithms used depend upon the types of coinciding materials. There is a priority among materials within EMA3D. From lowest to highest priority, the order of material types are graphically depicted below:

If two backgrounds are coincident or overlapping, then the last one to appear in the EMA3D input file takes precedence. All backgrounds take precedence over the implicitly programmed vacuum background mentioned above. If two or more isotropic materials are coincident or overlapping, then an averaging algorithm for the electromagnetic parameters is implemented which derives new values of the conductivity, permittivity, permeability, and magnetic conductivity at the coincident locations. If two or more anisotropic materials are coincident or overlapping then the last one to appear in the input file takes precedence. This is also true with frequency dependent materials. If an anisotropic or frequency dependent material overlaps an isotropic material then the former takes precedence. Perfectly conducting materials take precedence over all materials and all materials take precedence over the background media. The advantage within the above priority list is the ability to place objects or geometries of one material type within those of another without creating a hole in the latter material. Creating holes can become tedious, if required often, and can result in substantially larger EMA3D input file sizes.

In addition to material priority, there is also geometric priority. In the EMA3D input file, there are entities termed bodies, surfaces, and lines. Bodies possess three dimensional bulk characteristics, surfaces are topologically two-dimensional entities, and lines are one-dimensional. A fourth entity termed “points” is also allowed within EMA3D. Points within EMA3D are nothing but lines that are one lattice or mesh increment long. The advantage of geometric priority is the ability to place certain objects or geometries within others without having to create a hole. For instance, a line of isotropic material of one type can penetrate many bodies of isotropic materials of other types without compromising the inherent electromagnetic parameter values to the algorithms of averaging.