We demonstrate a technique that automatically tunes the sensitivity of a radio-frequency (RF) interferometer with a tunable liquid attenuator by accurately changing its liquid volume. The obtained effective quality factor (Qeff) of the interferometer is up to 1 × 108 at ~5 GHz. The Qeff is ~100 times higher than previously reported results. When material-under-test (MUT), i.e., methanol-water solution in this work, is used for the tuning, a self-calibration and measurement process is demonstrated from 2 to 7.5 GHz at a methanol concentration level down to 5 × 10-5 mole fraction, which is 100 times lower than previously reported results. Further investigations are needed to achieve better system stability and higher sensitivity.

中文翻译：

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高灵敏度射频干涉仪的自动调谐和自校准

我们展示了一种技术，该技术通过准确改变液体体积来自动调整带有可调液体衰减器的射频 (RF) 干涉仪的灵敏度。干涉仪获得的有效品质因数 (Qeff) 在 ~5 GHz 时高达 1 × 108。Qeff 比之前报告的结果高约 100 倍。当使用被测材料 (MUT)，即本工作中的甲醇-水溶液进行调谐时，在 2 至 7.5 GHz 范围内，甲醇浓度水平低至 5 × 10 时演示了自校准和测量过程-5 摩尔分数，比之前报告的结果低 100 倍。需要进一步研究以实现更好的系统稳定性和更高的灵敏度。