Introduction to GLMoM

GLMoM is an electromagnetic field simulation software which uses Method of Moments and Green's functions for multilayered medium.

GLMoM can solve 4 types of problems:

• Scattering problem: given incident field and structure, calculating the current distribution and scattered field. Applications includes radar cross section (RCS) calculation.

• Resonance problem: given the structure, calculating its complex resonant frequency and resonant mode. Applications include cavity resonators.

• Antennas or circuits excited by localized voltage source: given the structure and location of sources, calculating the Z, Y and S matrices; given amplitude and phase of sources, calculating the current distribution and radiation field.

• Antennas or circuits excited by transmission lines: given the structure and location of port, calculating the S matrices; given amplitude and phase of incident waves at ports, calculating the current distribution and radiation field.

GLMoM considers the structure to be simulated as objects in an 'environment'. GLMoM currently is capable of simulating two types of environment:

• A homogeneous medium, in which case the whole space is filled with one uniform medium.

• A multilayered medium. The whole space is divided into many horizontal layers. Each layer extends to infinity in horizontal directions. The top and bottom layer may be dielectric or perfectly electrically conductive (PEC).

GLMoM uses Green's functions to account for environment effect and does not mesh environment. It only meshes the objects. Currently it can simulate PEC objects.

Generally a simulation includes the following steps:

1. Generating a triangular mesh for the objects. This can be done by executing a meshing script in GLMoM, or using other softwares and export to GLMoM by using RAW file format.

2. Setting the medium (enviroment) in which the objects reside. For multilayered medium, you can set the parameters for each layer, save them as a .med file, or load an existent .med file. You can also specify the algorithms for calculating the Green's functions and their parameters.

3. Specifying the excitation

   • For scattering problem, you need to specify the direction and polarization of the incident wave

   • For structures excited by microstrip lines, you need to specify the location of delta-gap voltage sources, and the portion of the microstrip line which are used to extract S-parameters.

   • For structures excited by delta-gap voltage sources, you need to specify the location of the sources.

4. Doing simulation. You can specify the frequency range to sweep for the structures excited by voltage sources or microstrip lines. The s-parameters are saved in Touchstone format.

5. Post-processing. You can display the current distribution, charge distribution and the electric field.