This thesis addresses the design of ferrite cores for inductive proximity sensors of the ECKO type. The purpose of this pursuit is to identify several ferrite cores that have the highest performance in terms of the sensor's sensing ability. The purpose of the ferrite core in these sensors is to concentrate and focus the alternating magnetic field produced by a current-carrying winding. The magnetic flux is specifically aimed at the sensor's metal target, and since the sensing operation is dependent on the generation of eddy currents within the metal target, the range at which the target can be detected is a direct function of how optimally the magnetic flux is cut by the target. In this study the target is a circular disk, just as is used in industry for standardization procedures. To begin with, a theoretical analysis is performed to identify those factors that affect sensing performance; this development makes use of fundamental electromagnetic theory. Subsequently, the performance of a score or so ferrite geometries is evaluated by computer simulation using the results of the theory to facilitate effective comparison. The computer simulation is performed using finiteelements based electromagnetics solver software from ANSOFT. Lastly, some of the geometries studied with the simulation are constructed and their sensing performance evaluated as verification of the simulation and its theoretical backing. / Master of Science