Modeling complex systems for EMC and signal integrity

Full wave electromagnetic modeling tools and techniques are well suited to give very accurate results to relatively limited problems, such as shielding effectiveness of simple enclosures, effects of vias in printed circuit boards (PCBs), effects of grounding heat sinks on PCBs, and many others. However, real world systems are very complex and much more complicated than these simple structures. Although today´s techniques and computer systems allow modeling of much more complex structures than in the past, it is still very unrealistic to expect to use full wave EM tools for complete systems except in very limited cases. This paper describes recent applications of very large models using various modeling techniques. The limits for practical amounts of RAM and solution time are discussed. Another approach to solving large complex problems is to break the problem into smaller portions, solve each portion individually, and then combine the results from each portion into an overall solution. The individual portions must be able to be analyzed individually and not be affected by other individual portions of the overall problem. This paper gives some examples of this requirement and discusses how to determine if this requirement is met or not.