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A sequential computer
program was written based on the formulation developed in Chapter 3. This
code was merged into the ParaMoM code previously developed by Cha's group
at SRC based on the formulation derived in Chapter 2. In this section, we
discuss the
ParaMoM features and its program structure.
There are two major components in the ParaMoM package: the target model
processing software and the MoM code itself. The target model processing
software generates the target model using CAD and a model processor for input
into the MoM code. The package is capable of accepting data files that
consist of a limited class of Initial Graphics Exchange Standard (IGES)
data types, as well as files from SCAMP which is a computer-aided design (CAD)
package. The model processor allows the user to perform the following
tasks:
- specify wires as either radiating antennas or scatterers
- place distributed load impedances on both surfaces and wires
- place lumped loads at antenna feed nodes
- find the intersection of wires and surfaces
- view a simple, coarse grid version of the model
- triangulate all curved surfaces (and subdivide all wires) according
to a specified maximum edge length
- specify planes of symmetry
The output of the model processor (DC file) is in a format that can be read
by the MoM program. It can also be read back in to the model processor to
be regridded, or have its wire or material impedance characteristics
modified.
Some of the capabilities of the MoM code in this package are summarized as
follows:
- For curved surfaces with a parametric description, a new basis
function has been used.
- Three operator equations have been implemented; electric, magnetic,
and combined field integral equations.
- In addition to the default of perfect electric conductors (PECs),
objects can be described using a surface impedance value in units of ohms
per square. This is intended for either a material sheet
(for example
an R-card) of finite conductivity or a dielectric material coating on a PEC
surface and is handled within the E-field formulation.
- A target with mirror symmetries can be treated by only modeling a
portion of the target and specifying up to three planes of symmetry.
- Wires can be included in the model. They may be separate or connected
to surfaces. Where they are connected to surfaces, appropriate junction
basis functions will be used (see Reference [66]).
- The user may compute either radiation or scattering due to wire
antennas.
- The desired far-field pattern can be computed for a variety of
monostatic and bistatic configurations.
- The far-field patterns can be computed for up to 16 different
combinations of transmit/receive polarizations (four receiver polarizations
for antenna gain) in a single run.
The ParaMoM's structure is shown in Figure 4.4. A brief
description of each box in Figure
4.4 is given below:
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