Microwave antenna array for high temperature materials processing

Industrial scale high temperature microwave processing of materials, like e.g., dielectric heating for sintering or heat treatment of powder metals and ceramics has not been successful yet, mainly because of lack of suitable equipment. The paper presents results of antenna development aiming at 2.45 Ghz microwave transmission into hot processing chambers, with minimum heat loss because only minor cooling of windows or transmission lines is required. High power microwave coupling is enabled by an array of high temperature resistant rod antennas. The design is performed in two steps: first simulation (FDTD) and experimental validation is done for a single antenna, than the results are transferred into the design of a 6 antenna array. This antenna array is capable of transmitting up to 36 kW 2.45 GHz radiation into a 1m³ volume process chamber at temperatures up to 1500°C. The E-H-field distribution and the limitations of material selection for the antenna array are discussed.