Electromagnetic simulation - Design tools

With the increasing complexity of microwave and millimeter-wave circuits, and electronic devices in general, it has become necessary for design engineers to predict the behavior of these systems with simulation tools using rigorous models. These are based on the equations governing the electromagnetic field established by Maxwell in the 19th century. For a long time, the focus has been on finding solutions to these equations in the presence of any geometry. Although certain numerical methods had long been known, their use was soon limited by the limited computing resources available at the time. With the rapid development of computers, these methods and new approaches have received a great deal of attention. Their development now makes it possible to solve problems where the geometry and media can be virtually arbitrary, albeit with limitations.

Numerical electromagnetic calculation tools are an indispensable element in device design. They are capable of taking into account all electromagnetic coupling and radiation effects, at least as rigorously as possible, effects which are generally not negligible in electrodynamics. As a result, they have to be part of the loop of an optimization procedure leading to an optimal solution for a device. However, computers have limited computing power, and the cost of calculation increases rapidly with the electrical size of the structures studied. It is still difficult to include electromagnetic analysis directly in the computer-aided design (CAD) procedure. Admittedly, we are experiencing rapid growth in computer processing power, which currently doubles every eighteen months or so. Unfortunately, this growth is always offset by an increase in the complexity of the systems to be studied. It's worth noting that this has encouraged research into improving the efficiency of numerical modeling methods.

It would be ambitious to provide a critical overview of all existing methods and to rank them according to their advantages and disadvantages. We will therefore limit ourselves to mentioning the main methods, which are the driving force behind the best-known commercial and laboratory software for electromagnetic device analysis. We might ask why it is necessary to study several methods when they all have the same objective, i.e. to solve Maxwell's equations. In fact, it often turns out that Maxwell's equations are first manipulated to produce an equation better suited to the type of problem. This important step is called problem formulation. Then, this equation is solved by the application of a numerical method, which is nothing other than an application of numerical analysis. Consequently, the advantages of one method over another depend very much on the type of problem to be solved. Mainly, the complexity of the geometry, non-linear...