Optimization of Stream-Function-Based Coil Heads for EMI Systems

Many different coil head configurations are used in electromagnetic induction (EMI) systems for sensing buried targets, but these coils are most often designed by altering known winding configurations because a general wire parameterization is difficult to create and to optimize for target sensitivity. The soil sensitivity, which is important in mineralized soils, is also often not taken into account. This work presents a method of parameterizing wire coils using stream functions. A new set of normalized metrics for analyzing the coils as stream functions is demonstrated, and then the metrics and stream functions are optimized using a new biconvex optimization procedure. The stream functions are then converted back into wire coils to demonstrate the efficacy of the stream-function parameterization. Results show an improvement in target and soil sensitivity performance over known conventional wire coil configurations.