A Uniform Heating Technique for Cavity in Volatile Organic Compound (VOC) Removal System Using Slotted Waveguide Array

Abstract

In this study, two types of slotted waveguide are designed in the frequency of 2.45 GHz to improve the microwave heating uniformity of a quadrangular prism-shaped cavity in a volatile organic compound (VOC) removal system. Both types adopt the equivalent circuit approach used for a waveguide slot array antenna. The difference between the two types is the slot impedance extraction method of the waveguide slot array: one calculates the impedance taking the cavity structure into account and the other finds it in free space. Both methods show that the heating uniformity is improved by 52% compared with that of the conventional horn-type feeding structure system according to the simulation results. Even though there is no difference in the heating uniformity between the two models, it is confirmed that the slotted waveguide array feeding model designed by using the impedance data of the slot incorporating the cavity (SAWFM_cavity) has about 6.35 dB better impedance matching characteristics than the other model designed by extracting the impedance data of the slot in free space (SAWFM_free). Also, it is found that the SAWFM_cavity shows more stable impedance characteristics with respect to the loading condition than the SAWFM_free. Therefore, it is concluded that the impedance of the slot should be extracted taking the cavity into account for the design of the slotted waveguide feeding structure since it improves the reflection characteristic as well as the heating uniformity compared with the horn-type feeding structure.