Abstract: A microwave generating device includes a cabinet defining a cavity provided with an opening with an edge portion of the cabinet defining the periphery of the opening. A closure impervious to microwave energy extends removably across the opening and includes a peripheral portion overlying the cabinet edge portion. Structure is provided for preventing loss of microwave energy outwardly between the closure peripheral portion and the cabinet opening edge portion including cooperating surface portions on the closure peripheral portion and cabinet opening edge portion facially juxtaposed when the closure is disposed across the opening to define a capacitive seal against transmission of microwave energy outwardly therebetween. A metallic frame extends about the closure peripheral portion and includes a recess opening toward the capacitive seal to define a wave trap having a length preselected to be effectively one-quarter the wavelength of the microwave energy.

Abstract: A waveguide structure for use in a microwave oven wherein a portion of the wall structure defining the oven cavity also forms a portion of the waveguide. The waveguide is formed of a plurality of wall members cooperatively defining a waveguide conduit for delivering microwave energy from a generator through an inlet opening in the oven cavity wall. The several wall members of the waveguide conduit are pressformed and secured together by mechanical fastening structure to provide high accuracy in the waveguide configuration. The conduit wall further includes a mounting flange secured to the cavity wall to provide further precise accurate association of the waveguide conduit with the cavity wall opening. An external paint coating on the cavity wall defines with a mounting flange of the waveguide conduit wall a capacitive seal therebetween.

Abstract: An improved air circulation system for a microwave oven having an improved air inlet for delivering ambient air to the microwave energy generating device. The air inlet is defined in part by a formed portion of the cabinet providing an air channel to the front and rear of the oven for subsequent flow to the generating device. A first portion of the delivered air is conducted to the oven space while a second portion of the air is heated by heat transfer association with the magnetron structure of the generating device. The heated air is subsequently divided into two paths. In one path, the heated air is directed through a suitable outlet to exteriorly of the cabinet. In the other path, the heated air is directed through an upper cavity portion of the heating space to a rear portion of the lower oven cavity. The heated air, together with the air delivered substantially directly from the generator space to the lower cavity, is discharged through a front, upper opening of the cabinet.