Disclosed are method and apparatus for measuring material properties. Segmented field sensors have multiple sensing elements at different spatial geometries to capture field components having substantially different depths of penetration. These sensors are excited and measured on these different sensing elements to facilitate characterization of unknown material properties. This is illustrated in some embodiments using eddy current sensors to characterize materials that are frequency dispersive and/or do not produce a measurable phase shifts. Only a single scalar quantity may provide independent information from one or more of the sensing elements. Property estimation techniques, such as those using precomputed databases of sensor responses are used to estimate the unknown material properties.