Generating electromagnetic fields in a self regulating temperature heater by positioning of a current return bus

A method for fabricating a self-regulating heater of the type is energized by an alternating current having a known frequency, said method comprising the steps of:

• (a) fixedly disposing a magnetic material surface layer on at least a portion of a surface of an non-magnetic, electrically-conductive substrate, said magnetic material having a substantially higher resistance than said substrate, said surface layer having a depth corresponding approximately to one skin depth of said magnetic material at said known frequency;
• (b) defining a longitudinally extending slot through the entire thickness of said substrate such that the slot is disposed spaced from opposite longitudinal ends of said substrate such that there are two fold sections joining first and second heater sections, the fold sections being located at opposite longitudinal ends of said slot;
• (c) folding the substrate through the two fold sections and slot such that the first and second heater sections are closely spaced and substantially parallel and in which said surface of said first heater section faces said surface of said second heater section;
• and
• (d) removing one of said fold sections.