A dual-material strategy for enhancing the temperature robustness of microwave resonant cavity

Resonant frequency varies significantly due to temperature changes for microwave resonant cavities. Hence, temperature robustness enhancement is of great importance. In this paper, a resonant cavity with enhanced temperature robustness is proposed by applying the dual-material strategy to the middle cavity. Compared to the single-material cavity, the dual-material cavity can demonstrate better temperature robustness with a decrease of 72.7% in the frequency shift over the temperature range of −20 to 80°C. Moreover, the |S11| < −10 dB impedance bandwidth is 6.3% (3.39–3.61 GHz) and the gain is 20.4 dBi at 3.5 GHz for the manufactured dual-material cavity, which are much better than those of the manufactured single-material cavity. Finally, an experiment is conducted to measure the resonant frequencies with the sample solution tube of the dual-material cavity filled with nothing or 30 mg/dl CuSO4 solution, the measured values are consistent with the simulated ones. The influence of temperature drift is significantly reduced, and the feasibility of the dual-material strategy is verified.