Abstract: An electromagnetic energy seal for use in a microwave oven comprises a first sealing cavity formed along at least one of a peripheral edge portion of an entrance opening of a heating chamber and a portion of a door for opening and closing the entrance opening of the heating chamber which is opposite to the peripheral edge portion of the entrance opening of the heating chamber, and a second sealing cavity disposed in the opening of the first sealing cavity. These first and second sealing cavities have a simple structure which produces high shield effects against the fundamental microwave frequency and the higher harmonic microwave frequency components thereof, respectively, and the adjustment and optimization of the choking frequency characteristics of the cavities can be made easy.

Abstract: This invention is designed to make uniform the heating of the object inside the heating chamber by turning an internal waveguide which is roughly in a foldable fan shape and located at the bottom of the heating chamber in a structure adapted for feeding high frequency electric waves from the bottom of the heating chamber. In order to have stable gyration of the internal waveguide, and annular protrusion made of a low loss dielectric is placed between the low impedance parts provided on the internal waveguide and the heating chamber bottom surface. In this way, a rotary structure which is economical, easy to assemble and reliable can be realized.