Multimode cavity with circular polarizing patch array to heat thin material by microwave

In order to heat low loss materials by microwave, it is necessary to converge the power density. In this study, to heat low loss thin materials such as thin film and sheet by microwave in the multimode cavity resonator, circular polarizing patch array is developed. The patch array is set in the multimode cavity with the major axis of patch is set as 45 degree to the orientation of the fed electric field. This arrangement generates circular polarized electric field in the cavity resonator. The metallic patch array in the cavity becomes the secondary radiator of microwave, and the electric field power density becomes large on the surface of the patch array radiators. The heating medium is set and moved on the surface of the patch array and the high electric field on the patch can heat low loss material effectively. Also, the patch array is useful to make the electric field distribution uniform inside the cavity. By optimizing the shape and the arrangement of patch, the heating pattern of thin material becomes uniform and strong electric field is irradiated at the frequency of 2.45 GHz. By using this method, uniform heating for low loss thin material can be performed by microwave.