Abstract: There is disclosed a microwave applicator which is positioned above an electrically conductive conveyor band on which products, such as biscuits in a baking oven, are carried to be subjected to microwave radiation, the applicator having a launch section configured to provide an electric field in the region above the band which is that which would exist in a parallel plate transmission line extending lengthwise of the oven, the electric field having a plane of polarity which is normal to the plane of the band.

Abstract: 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 in a waveguide which are brought to resonance in the presence of pre-packed articles carried over the slots by a conveyor the rate of rise of temperature within the article is controlled without unnecessary energy loss between articles carried seriatim on the conveyor The slots may be set obliquely to the direction of passage of the article Alternatively the slots may be formed by a series of smaller slots staggered obliquely across the waveguide so that the presence of the article 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.

Abstract: Microwave apparatus for heating discrete packages (12) of product. The microwave apparatus has a support surface (14) for a packaged product within a waveguide (2), a microwave field generator, and field deflecting and concentrating guide (4,6) to produce a raised value of energy in the field in the interior region of the package so as to uniformly heat the package (12).