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A simple, tunable, and highly sensitive radio-frequency sensor
1Department of Electrical and Computer Engineering, Clemson University, South Carolina 29634, USA.
Abstract:
We report a radio frequency (RF) sensor that exploits tunable attenuators and phase shifters to achieve high-sensitivity and broad band frequency tunability. Three frequency bands are combined to enable sensor operations from ∼20 MHz to ∼38 GHz. The effective quality factor (Q ) of the sensor is as high as ∼3.8 × 106 with 200 μl of water samples. We also demonstrate the measurement of 2-proponal-water-solution permittivity at 0.01 mole concentration level from ∼1 GHz to ∼10 GHz. Methanol-water solution and de-ionized water are used to calibrate the RF sensor for the quantitative measurements.
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