A card core includes a body defining a cutout and a discontinuity. The cutout includes an opening in the body defined by an edge and the discontinuity includes a channel defined by the body extending from an outer surface of the body to the cutout. At least one circuit element is positioned within the cutout. The cutout defines a size and geometry such that a gap is defined between the at least one circuit element and the edge to electromagnetically isolate the at least one circuit element from the body.