The Method of Moments in Electromagnetics

Chapter 1Computational ElectromagneticsBefore the digital computer was developed, the analysis and design of electromagneticdevices and structures were largely experimental. Once the computer and numericallanguages such as FORTRAN came along, people immediately began usingthem to tackle electromagnetic problems that could not be solved analytically. Thisled to a flurry of development in a field now referred to as computational electromagnetics(CEM). Many powerful numerical analysis techniques have been developedin this area in the last 50 years. As the power of the computer continues to grow,so do the nature of the algorithms applied as well as the complexity and size of theproblems that can be solved.While the data gleaned from experimental measurements are invaluable, theentire process can be costly in terms of money and the manpower required to dothe required machine work, assembly, and measurements at the range. One of thefundamental drives behind reliable computational electromagnetics algorithms is theability to simulate the behavior of devices and systems before they are actually built.This allows the engineer to engage in levels of customization and optimization thatwould be painstaking or even impossible if done experimentally. CEM also helps toprovide fundamental insights into electromagnetic problems through the power ofcomputation and computer visualization, making it one of the most important areasof engineering today.1.1 COMPUTATIONAL ELECTROMAGNETICS ALGORITHMSThe extremely wide range of electromagnetic problems has led to the developmentof many different CEM algorithms, each with its own benefits and limitations.These algorithms are typically classified as so-called “exact” or “low-frequency” and“approximate” or “high-frequency” methods and further sub-classified into time- orfrequency-domain methods. We will quickly summarize some of the most commonlyused methods to provide some context in how the moment method fits in the CEMenvironment.1