Improved uniformity of microwave heating

摘要

A system comprises a shallow container (11 a-11 d) and a load (10) located therein for heating by microwave energy. The system is designed either to be used with, or itself to incorporate, a structure for generating or enhancing at least one mode of the microwave energy of an order higher than a fundamental mode, the latter being determined by boundary conditions resulting from the lateral dimensions of either the container or the load or both. The invention resides in controlling the depth (d) of the load in the container in such a manner that, upon irradiation of the product with the microwave energy, the power absorbed by the load from a higher order mode is at or near a maximum value, while preferably the power absorbed by the load from the fundamental mode is at or near a minimum value. Since uneven heating would ordinarily be associated with the predominance of a fundamental mode, the result of this invention is to increase the intensity of a higher order mode relative to the fundamental mode intensity, and thus provide improved uniformity of microwave heating.