Electromagnetic interference or compatibility is a challenge faced by circuit designers across all areas of research, applications and industries, and is the subject of strict regulatory requirements. Darney's Circuit Modelling for Electromagnetic Compatibility, 2nd Edition shows how the analytical tools of circuit theory can be used to simulate the coupling of interference into, and out of, any signal link in the system being reviewed. This approach offers EMC testers and product designers a tool to work with at an early stage, before running expensive Faraday cage tests, which offers insight into whether a design is on the right track to achieving its design specification and so saving time and money.

The equipotential earth is a fundamental requirement of circuit theory, because it dramatically reduces the complexity of the mathematics required to simulate a circuit. Unfortunately, in the real world, no such equipotential earth exists, nor can it ever do so, which means simulating a circuit to evaluate its electromagnetic compatibility (EMC) and susceptibility to electromagnetic interference (EMI) is largely dependent on using the Maxwell equations. The Maxwell equations are inherently complex, however, and so have high processing power requirements and, as with all complex systems, there is a propensity to generate and magnify errors.