Modeling of the EM inductive‐limit surface currents

Abstract

The inductive limit of an electromagnetic (EM) response, which is the early time or infinite‐frequency response, may be quickly and efficiently calculated when compared to the effort and time required to calculate a full 3-D EM model. This can be achieved through matrix solution of a simple set of simultaneous conditions that any primary magnetic field must not penetrate the target body. In airborne EM (AEM) data acquisition, hundreds of local anomalies may need to be interpreted each day of flying, and the inductive limit modeling algorithm provides a useful and very fast model for realistic target geometries. In particular, it allows typical single‐peaked field anomalies in the vertical component of fixed‐wing AEM systems to be fitted, using a multi‐faceted solid body. Thin‐plate models, which are commonly used, produce “M-shaped” responses rarely seen in field data.