Injection-locked magnetron system with frequency-phase sweeping for improvement of heating uniformity in microwave ovens

Abstract As people continue to pursue an enhanced cooking experience, this paper proposes a microwave heating uniformity improvement system that effectively integrates the benefits of injection-locking technology. This system facilitates microwave frequency and phase scanning by integrating an external injection structure. A microwave heating cavity optimized for uniformity improvement system requirements is designed by simulation of the voltage standing wave ratio within the heating cavity. Properly tuning the impedance matching between the load and the transmission line’s characteristic impedance ensures that the standing wave ratio remains below 10, effectively mitigating arcing issues induced by excessive field intensity. Furthermore, uniformity experiments were conducted on the heating system comprising the newly designed heating cavity and the external injection structure. Experimental results demonstrate that, within a 30 MHz frequency range around the magnetron’s center frequency and over a 360° phase sweep, the heating uniformity was enhanced by up to 48.19% for thermal response paper and 92.08% for steamed buns. The uniformity enhancement effect is significant.