Abstract: Trays placed in an autoclave are coupled with microwaves from microwave generators and move back and forth as they are processed to ensure even heating. The generators are placed at the side of the autoclave so each generator connects to a wave guide in the autoclave with upwardly directed decoupling openings immediately below the tray to be heated. The distance between the decoupling opening and the tray is maintained at less than one-half wavelength. The foods on the tray are heated first from below and then the heat rises. When water in the lower food layers is heated, steam forms and must pass through the cooler upper layers to escape. As it does so, it loses heat to these layers, warming them and preventing scorching on the food's surface as well as any bursting of the trays' seal.

Abstract: The invention relates to a method and a device for microwave-heating prepared meals sealed in trays, in which the trays are placed in an autoclave into which microwaves from microwave generators are coupled and in which the trays are moved back and forth as they are being processed. It is the object of the invention to achieve appropriate, even heating of the different products on each tray and to prevent both hot spots and cold spots. The invention lies in the fact that the microwave generators are disposed at the side of the autoclave and are each connected to a waveguide arranged in the autoclave and comprising upwardly directed decoupling openings immediately beneath the tray, the distance between the decoupling opening and the tray to be heated being less than one-half wavelength. What is achieved in this manner is that the foods deposited on the tray are first heated from below and the heat rises from bottom to top. This prevents overheating and burning on the surface.