Frequency-reconfigurable TM010-mode reentrant cylindrical cavity for microwave material processing

This paper proposes a frequency-reconfigurable microwave reactor based on the reentrant cylindrical resonant cavity. It works with the TM010-associated mode and is able to resonate at every frequency in the range of 500–950 MHz, i.e., 62% tunable relative bandwidth. Considering the practical requirements of microwave processing, especially for the single processing capacity and the wide frequency bandwidth, the theory and design formula for the existing reentrant cylindrical resonant cavity are no longer applicable. Consequently, a new method to control the resonant frequency is proposed. The corresponding approximate design formulas are derived to show the relationship between cavity’s dimension and its electric properties (resonant frequency and quality factor). Their correctness is validated by the full-wave simulation. Furthermore, an effective feed method is developed to achieve good matching over a wideband frequency band. Within a volume of 502 mm3, relatively homogeneous -field can be generated at every operation frequency with the strength more than 105 V/m, while the single processed capacity keeps unchanged. Most of the microwave energy is concentrated within the processed region to achieve a high efficiency. This microwave reactor presents an excellent candidate in the application of a frequency-reconfigurable microwave processing system to recognize the optimal absorbent frequency for a special microwave reaction.