Patent ID: 8426786

Claim:
A self-supporting field director structure for use in heating an article in a microwave oven, the field director structure comprising: a plurality of vanes, each vane extending radially outwardly from a central axis, each vane being angularly adjacent to two other vanes, each vane having a radially inner and a radially outer end, the vanes being attached to each other at their inner ends, each vane being formed from a pair of electrically non-conductive outer laminae, the outer laminae each having a predetermined coefficient of thermal expansion, and an inner core formed of an electrically conductive material having a predetermined coefficient of thermal expansion that is different from the coefficient of thermal expansion of the outer laminae, the inner core being attached to each of the outer laminae, each vane having a predetermined thickness dimension, each of the outer laminae having border regions thereon that extend beyond the inner core, the non-conductive outer laminae being attached to each other along the border regions, the inner core and the outer laminae being arranged in a laterally symmetric fashion with the inner core being completely enclosed within the non-conductive outer laminae, so that thermal expansion effects due to heating are equalized across the thickness of each vane.