The determination of magnetic distortion fields caused by inclusions hidden in a
conductive matrix using homogeneous current flow needs to be addressed in multiple tasks of
electromagnetic non-destructive testing and materials science. This includes a series of testing
problems such as the detection of tantalum inclusions hidden in niobium plates, metal inclusion in
a nonmetallic base material or porosity in aluminum laser welds. Unfortunately, straightforward
tools for an estimation of the defect response fields above the sample using pertinent detection
concepts are still missing. In this study the Finite Element Method (FEM) was used for modeling
spherically shaped defects and an analytical expression developed for the strength of the response
field including the conductivity of the defect and matrix, the sensor-to-inclusion separation and the
defect size. Finally, the results also can be useful for Eddy Current Testing problems, by taking the
skin effect into consideration.