A method of computing the sensitivity of electromagnetic quantities to changes in materials and sources

This paper presents a method of computing the sensitivity of electromagnetic quantities (e.g. induced voltage, force, field uniformity) to perturbations in sources and material parameters. The method applies to systems with linear materials and time harmonic source currents; static problems are included as a special case. Sensitivity is equivalent to the derivative with respect to the distributed system parameters. Therefore, with the expressions for the sensitivity presented in this paper, first order optimization methods can be applied to optimization problems in electromagnetics. Applications are in the area of inverse problems, including electromagnetic device design, device optimization, and imaging