Improvements to microwave heating devices

摘要

In the heat treatment of food particularly pre-packed food it is important to control the temperature and to provide uniform heat distribution within the article. By using a number of microwave emission slots (13) in a waveguide (6) which are brought to resonance in the presence of pre-packed articles (12) carried over the slots by a conveyor (14) the rate of rise of temperature within the article is controlled without unnecessary energy loss between articles carried seriatim on the conveyor (14). The slots (13) may be set obliquely to the direction of passage of the article (12). Alternatively the slots may be formed by a series of smaller slots staggered obliquely across the waveguide (6) so that the presence of the article (12) tunes each of the slots in turn as it passes over the waveguide. The slots may be covered with low-loss dielectric material to prevent extraneous matter falling into the slots and to space the article from the slots so as to control power dissipated.