Microwave oven excitation system for promoting uniformity of energy distribution

Claim 1

In a microwave oven of the type including a source of microwave energy of a predetermined center frequency and wavelength, a rectangular waveguide having an end coupled to the source of microwave energy, and a box-like rectangular cooking cavity capable of supporting a plurality of electromagnetic standing wave modes, an excitation system comprising: a relatively flat mode stirrer cavity including a mode stirrer, said mode stirrer cavity having a horizontal extent sufficient to support a plurality of half-waves of standing wave energy in each of two orthogonal orientations, said mode stirrer cavity thus being a resonant cavity capable of storing microwave standing wave energy, and said mode stirrer cavity having an opening in one side wall connected to receive microwave energy from the other end of the waveguide; a fixed common wall separating said mode stirrer cavity and the cooking cavity; and at least two aperture elements of generally slot configuration in said common wall for coupling microwave energy from said mode stirrer cavity into the cooking cavity, said aperture elements being oriented at right angles to each other.