Introduction
When simulation is run using an LC model, the first step is
to convert data structures representing the ideal model geometry
into a form suitable for the FD-TD electromagnetic solver.
This process is referred to as mesh generation.
This document describes the mesh generation algorithm in LC.
LC Model
An LC model contains any number of adjacent, overlapping,
or disjoint geometry blocks which define the material
electromagnetic properties in that space.
The blocks may be of just two primative shapes:
rectangular or cylindrical.
More complex shapes can be created by combining several
primative blocks.
For example, a conductor with a right-angle turn can be
created with two adjacent rectangular blocks.
In addition to the geometry blocks which define the material
properties of the model, active blocks are used for source
excitation, loads, and calculating probe output values.
These active blocks are mapped into the FD-TD mesh and
interact with it during the simulation.
FD-TD Mesh
The FD-TD mesh is a rectangular space containing two cartesian
grids, one for the electric field and one for the magnetic field.
Each grid is composed of uniformly distributed nodes spaced by
the cell width.
The nodes define the corners of 3D cells, the faces of the
3D cells define 2D cells, and the edges define the electromagnetic
vector field components.
The two grids overlap, but are displaced by half of a cell width
in each dimension.
The nodes are indexed by (i,j,k) coordinates with the half
cell displacement assumed.
The electric field grid contains nodes from (0,0,0) to
(imax,jmax,kmax), while
the magnetic field grid contains nodes from (0,0,0) to
(imax-1,jmax-1,kmax-1).
Thus, the electric field components define the faces of the simulation
domain, while the magnetic field components are all internal to the mesh.
