Abstract: A system is provided for heating sealed packages with microwaves, in particular under enhanced pressure. At least two microwave frequency radiatiors are employed for obtaining a controlled heat distribution inside of an object to be heated and the two radiations are at least over a time average superposed. The object is disposed near the maximum high frequency field strength corresponding to the high frequency distribution of the sum field. The microwave heating system is provided as a continuous furnace, which comprises a tube for guiding the objects to be heated as well as one or more microwave emitters disposed next to each other in the transport direction. The tube is provided with two coaxial tubes inserted into each other, where one is a metal tube with entrance openings for the microwaves and the other is a plastic tube for pressure sealing of the entrance openings. Receiver containers are provided for the objects to be heated and transported.