A new coupling method for quarter-wave coaxial cavity resonator used for sterilization

In this paper, a new coupling method for the quarter-wave coaxial cavity resonator is proposed and designed for sterilization. The inner and outer conductors of the quarter-wave coaxial cavity is connected by two symmetrical inductive bend metallic stubs to achieve zero-voltage at the lower end of the resonator. The upper end forms an open circuit and the voltage has its maximum. Compared with other traditional coupling structures, such as loop coupling, this type of structure not only keeps good performance in simple configuration, but also has many additional advantages. For example, it can be integrated and fabricated with the conventional quarter-wave coaxial cavity resonator together to improve the fabrication accuracy and operation reliability. Besides, it has high repeatability and mass-producibility. The detailed design process is introduced in this paper. The proposed coupling structure and the corresponding quarter-wave coaxial cavity resonator are modeled, analyzed and simulated by the commercial software HFSS. The electric field near the upper end of the inner conductor can reach 10⁶ V/m, so it is sufficient to break the cell membrane and be used for sterilization. This simple and effective coupling method and the corresponding integrated resonator can be employed in the plasma excitation and dielectric measurement applications as well.