Verification of near-field calculations by conservation laws

Accurate solutions of Maxwell’s equation for monochromatic fields can be obtained by finite element analysis or by modal methods. Deviations from the accurate solution occur due to a finite mesh size or due to mode truncation. The intensity of the diffraction or reflection modes is usually easy to verify by experimental measurement. On the other hand, the verification of the intensity of near fields in most cases is very difficult or may be even impossible. Therefore, other ways of verification must be considered. In this talk we propose to apply conservation laws. Energy conservation can be used to compare the globally absorbed power to the integral of locally absorbed power. Another conservation law concerns the conservation of momentum. To this end we compare the global force acting on a structure to the integral over the local force.