 ### EM Modeling Software Acronyms and Definitions

ABC - Absorbing Boundary Condition
An mathematical technique for truncating computational regions that attempts to emulate an open boundary by absorbing all the incident electromagnetic energy. EM modeling techniques based on the solution of the differential form of Maxwell's equations require an absorbing boundary to model open radiation problems.
ACES - Applied Computational Electromagnetics Society
ACES is a professional society that provides a forum for issues relevant to numerical modeling in applied electromagnetics including computational techniques, electromagnetic modeling software, and applications.
AF - Antenna Factor
The ratio of the received field strength to the voltage appearing at the terminals of a receiving antenna OR the ratio of the transmitted field strength at a specified distance to the voltage applied to the terminals of a transmitting antenna. Antenna factors are functions of position and frequency.
BEM - Boundary Element Method
A popular electromagnetic modeling technique that employs the method of moments to solve electric or magnetic field integral equations. 3D BEM codes utilize mesh elements that are usually lines, rectangles or triangles covering the surfaces at the interfaces between two different materials.
BIE - Boundary Integral Equation
Another name for the Boundary Element Method (see above).
BI-RME - Boundary Integral - Resonant Mode Expansion
A method for the fast calculation of the modes of arbitrarily shaped hollow-conducting waveguides or cavities.
BOR - Body Of Revolution
An object that can be generated by rotating a generating arc about the axis of symmetry (i.e. in cylindrical coordinates can be oriented with its axis in the z direction and all surfaces will be described by functions that are independent of phi.)
CEFC - Conference on Electromagnetic Field Computation
A biennial conference sponsored by the IEEE Magnetics Society.
CFIE - Combined Field Integral Equation
A weighted combination of 2 integral equations: one relating electric currents and/or magnetic currents to electric field strength at a distance (EFIE); the other relating electric currents and/or magnetic currents to magnetic field strength at a distance (MFIE). Integration is over a surface for 3D problem geometries or over a line for 2D geometries. Boundary Element Methods (BEM) generally employ a moment method to solve an EFIE, MFIE or CFIE.
An iterative method for solving large systems of linear equations.
EFIE - Electric Field Integral Equation
An integral equation relating electric currents and/or magnetic currents to electric field strength at a distance. Integration is over a surface for 3D problem geometries or over a line for 2D geometries. Boundary Element Methods (BEM) generally employ a moment method to solve an EFIE, MFIE or CFIE.
EMAP - Electromagnetic Analysis Program
An EM modeling program based on a hybrid FEM/MOM technique distributed and supported by Clemson University.
EMC - Electromagnetic Compatibility
The ability of an electronic device or system to function without error in its intended electromagnetic environment.
EMLIB - (presumably ElectroMagnetic LIBrary)
EMLIB is a web site devoted to the free distribution of electromagnetic modeling software and related information.
The product of a transmitter power output and the antenna gain, taking into consideration any losses from the transmission line, connectors, couplers, etc.
ESA - Electrostatics Society of America
The ESA is a nonprofit professional society that is devoted to the advancement and improved understanding of electrostatics.
FDTD - Finite Difference Time Domain
A very popular numerical EM modeling technique that applies a finite differencing scheme to approximate the differential form of Maxwell's equations in the time domain. The technique typically used cubical mesh elements with an offset between E-field mesh nodes and H-field mesh nodes.
FEM - Finite Element Method
A popular numerical EM modeling technique that solves a differential form of Maxwell's equations, usually in the frequency domain. 3D FEM techniques typically employ tetrahedral or brick-shaped elements.
FEM-TD - Finite Element Method Time Domain (also FETD)
A numerical EM modeling technique that solves a differential form of Maxwell's equations in the time domain.
FIT - Finite Integration Technique
A numerical EM modeling technique that solves a differential form of Maxwell's equations in the time domain. It is similar in many respects to an FDTD technique, but it allows the mesh elements to have a non-cubical shape.
FSS - Frequency Selective Surface
A material surface that exhibits electromagnetic reflection or absorption properties that differ sharply at frequencies within a certain band.
FSV - Feature Selective Validation
A method for comparing two sets of data (for example, to quantify the agreement between measured and modeled results).
FVTD - Finite Volume Time Domain
A numerical EM modeling technique that solves a differential form of Maxwell's equations in the time domain. This technique is also similar to an FDTD technique, but it allows the mesh elements to have a non-cubical shape.
GEMACS - General Electromagnetic Model for the Analysis of Complex Systems
A commercial EM modeling code employing a 3D hybrid MOM/UTD/FDFD technique.
HFSS - High Frequency Structure Simulator
A popular numerical EM modeling code marketed by ANSYS based on a finite element modeling technique. Originally, this software was called the "High Frequency Structure Simulator" and was developed by AnSoft.
IEEE - Institute of Electrical and Electronics Engineers
IEEE is the world's leading professional association for the advancement of technology. The IEEE name was originally an acronym for the Institute of Electrical and Electronics Engineers, Inc. Today, the organization's scope of interest has expanded into so many related fields, that it is simply referred to by the letters I-E-E-E (pronounced Eye-triple-E).
MOM-TD - Method of Moments Time Domain
A relatively obscure electromagnetic modeling technique that employs a BEM/MOM solver, but operates in the time domain.
LU - Lower triangular / Upper triangular
A representation of a matrix as the product of two alternate matrices; one where all the elements in the upper right half of the matrix are zero, and one where all the elements in the lower left half of the matrix are zero.
MOL - Method of Lines
A technique for solving partial differential equations (PDEs) typically using finite difference relationships for the spatial derivatives and ordinary differential equations for the time derivative.
MOM - Method of Moments
A numerical method for solving integro-differential equations that expands the unknown quantity into a sum of simple "basis" or "expansion" functions, then weights the resulting set of equations using an equal number of "test" or "weighting" functions resulting in a set of N equations in N unknowns. [Note: Electromagnetic modeling codes employing the boundary element method (see BEM) are often referred to as moment method codes, because they generally employ a moment method technique.]
MOM-TD - Method of Moments Time Domain
A relatively obscure electromagnetic modeling technique that employs a BEM/MOM solver, but operates in the time domain.
MTL - Multiconductor Transmission Line
A cable or wiring harness with more than two wires usually carrying more than one signal.
NEC - Numerical Electromagnetics Code
A popular electromagnetic modeling code that is distributed freely. It applies a moment method to solve an electric field integral equation on wires and/or a magnetic field integral equation on surface patches. It is one of the most accurate and efficient thin wire modeling codes available. NEC2 is available as source code and uses a text-based interface. There are several commercial codes available that use the same basic technique, but add graphical interfaces and other features.
PDE - Partial Differential Equation
Describes any partial differential equation, but is often used in EM modeling to refer to the differential form of Maxwell's equations or modeling techniques that solve Maxwell's equations in this form.
PEC - Perfectly Electrically Conducting
Describes a material with infinite conductivity (i.e. will not support an electric field).
PEEC - Partial Element Equivalent Circuit
An electromagnetic modeling technique that breaks a problem geometry into small pieces and models all electromagnetic interactions between the pieces as circuit elements.
PMC - Perfectly Magnetically Conducting
Describes a material with infinite permeability (i.e. will not support a magnetic field).
PML - Perfectly Matched Layer
A particular type of absorbing boundary condition originally formulated by Berenger in 1994.
A frequency at which electromagnetic radiation of energy is useful for communications. Radio frequencies are designated as very low: 3 kHz to 30 kHz, low: 30 to 300 kHz, medium: 300 to 3,000 kHz, high: 3 to 30 MHz, very high: 30 to 300 MHz, ultrahigh: 300 to 3,000 MHz, super high: 3 to 30 GHz, and extremely high: 30 to 300 GHz.
RWG - Rao-Wilton-Glisson
Triangular basis functions used by many EM modeling codes employing moment method solution techniques. The functions are named after the three researchers who developed them: Sadisiva M. Rao, Donald R. Wilton and Allen W. Glisson.
SPICE - Simulation Program with Integrated Circuit Emphasis
Very popular circuit simulation software originally developed at the University of California, Berkeley and now distributed in many forms as implemented by a variety of commercial and non-commercial organizations.
TD-AIM - Time Domain Adaptive Integral Method
A numerical method for efficiently solving hybrid volume-surface integral equations.
TDIE - Time Domain Integral Equation
A unique EM modeling technique that solves the integral form of Maxwell's equations in the time domain.
TEM - Transverse ElectroMagnetic
An electromagnetic plane wave where the electric and magnetic fields are perpendicular to each other everywhere and both fields are perpendicular to the direction of propagation. TEM cells are often used to generate TEM waves for radiated immunity (RI) testing.
TLM - Transmission Line Matrix
An electromagnetic modeling technique that emulates electric and magnetic field interactions using circuit elements connected by a grid of transmission lines.
UTD - Uniform Theory of Diffraction
An electromagnetic modeling technique for modeling electrically large objects. The uniform theory of diffraction employs quasi-optical techniques and uses ray diffraction to determine diffraction coefficients for each diffracting object-source combination.
WPBC - Waveguide Port Boundary Condition
A boundary condition used in EM modeling to simulate the junction occurring at a waveguide or coaxial cable feed without having to model the interior of the waveguide or cable.