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.
