Just a decade ago, electromagnetic (EM) software simulation tools were still making their way from the university to the engineer's workstation or personal computer. In that relatively short time, however, EM software tools have evolved from experimental curiosities to essential design and analysis tools. It is safe to say that many of the advances in microelectronics and miniature mechanical structures, including microelectromechanical systems (MEMS) devices, would have proceeded at a much slower pace if not for the help of EM simulation tools.
The basic concept of an EM simulator is fairly simple: this is software based on Maxwell's equations and designed to leverage the processing power of a computer to solve these field relationships in a (relatively) short time. Time, of course, is one of the key issues with such a tool. A decade earlier, simulation run times of a week or more were not unheard of even for an analysis of basic structures or circuits. As programmers have learned to make more efficient use of the code surrounding Maxwell's equations, and computers have gotten faster, simulation times have become much more manageable and in line with the times required by SPICE and circuit simulation tools.
What makes an EM simulator so special, so invaluable? While a linear (or nonlinear) circuit simulator can analyze an oscillator circuit in terms of its network properties and spectral performance, an EM simulator can predict the EM field behavior of the components in the oscillator, the current distribution through those components and connecting transmission lines, and even the effects that a package will have on the ultimate output-power and spectral performance of the oscillator.
Of course, EM simulation tools do not fix every problem, but can at least provide a different viewpoint. Like most software programs, they are designed to work with other software tools, such as schematic-capture programs and circuit editors. Some EM simulators are stand-alone tools while others work as part of an integrated suite of design tools.
EM simulators are available from numerous suppliers, many of which who have been in this part of the field for well more than a decade. Support of an EM tool is not trivial, and requires comprehensive knowledge of both the tool and EM field theory—at least one of the reasons that a company choosing to enter this field would face fierce and knowledgeable competition.
To assist our engineering readers with the latest information on EM simulators, Editor Nancy Friedrich has assembled a special overview of the latest products and developments in the field, starting on p. 33.