An abuse-tolerant microwave food packaging material includes repeated sets of metallic foil or high optical density evaporated material segments disposed on a substrate. Each set of metallic segments is arranged to define a perimeter having a length equal to a predetermined ratio of the operating, or effective wavelength of a microwave oven. The repeated sets of segments act both as a shield to microwave energy and as focusing elements for microwave energy when used in conjunction with food products yet remaining electrically safe in the absence of the food products.