本論文提出應用於液體介電常數與濃度量測之高靈敏度雙主動式開口環共振腔(Dual Active Split-Ring Resonators, DA-SRR)微波感測器。藉由共振腔受外在待測物微擾(Perturbation)後所產生的共振頻率偏移以檢測待測液體之介電常數(Permittivity)，並且藉由主動式回授網路(Active feedback loop)之損耗補償(Loss compensation)概念，提升傳統被動式共振腔微波感測器之品質因素(Q-factor)，以提高感測器量測之靈敏度(Sensitivity)，克服傳統平面式開口共振腔感測器因本身製造材質及幾何架構之有限Q值，降低量測液體或高介電常數的量測靈敏度。一般來說，高介電值待測物，將使共振腔感測頻率偏移急遽減緩，降低感測元件檢測高介電值區間之分辨效能。應用此回授型高Q值微波感測器的設計架構可提供高分辨率(Resolution)和高靈敏度以區別液體微小濃度變化。
論文設計架構除了提高Q值之主動電路設計外，同時使用雙頻帶校正技術以準確地計算出液體濃度與介電常數。在實際量測結構中，量測液體待測物所需的量測容具（如微流管）會影響量測結果，增加誤差。在雙主動式開口環共振腔之雙共振頻率下(fL和fH)，透過所提出的分析理論，僅經此結構感測器之單次性量測，即可校正微流管所造成的量測影響。
在實際量測中，3.5~3.8 GHz操作頻率下，主動式開口環共振腔Q值由被動共振腔的49.7增加22倍到1098，因此將液體量測靈敏度提升了2.3~3.7倍，用於量測丙酮與水混合液體之濃度平均誤差為4.7 %較單一頻帶主動式開口環共振腔平均誤差6.9 %優。此技術結合雙主動電路提升Q值後不僅擁有高靈敏度的優點，並且藉由雙頻帶校正技術消除誤差項，以實現精準量測的微波介電質感測器。

This thesis proposed a high sensitive dual active split ring resonator (DA-SRR) microwave sensors to measure the permittivity and the concentration of the liquid. Due to the external perturbation impacts caused by the materials under test (MUT) on the SRR, the resonator generates a resonant frequency offset, which can be appled to detect the dielectric constant of the MUT or the test liquids. By an active feedback network to compensate the loss of the resonantor, the quality factor (Q-factor) of the traditional passive microwave resonantor can be enlarged. Therefore, the measurement sensitivity of the microwave sensor can be improved to overcome the finite small Q value of traditional planar SRR due to its manufactured materials or its geometric structure, implying reduction of the measurement sensitivity for the liquids or high dielectric constant MUTs. Moreover, as the permittivity increases to a high dielectric value, the resonant frequency offset become marginally shift, resulting in the degradation of the sensor resolution over the range of high dielectric value MUTs. Applying this high-Q feedback microwave sensor design can provide high resolution and high sensitivity to distinguish among the small change of the liquid concentration.
In this thesis, in addition to the high-Q design based on the active circuit, the simultaneous use of dual-band calibration techniques accurately estimate the concentration and the dielectric constant of the liquid. In practical measurement, the setup of the liquid measurement requires a container or a micro-fluid, which can affect the measurement results and increase the errors. Two resonant frequencies (fL and fH) can be obtained from DA-SRR. Based on the analytic theorem, the measurement errors caused by the mirco-flow can be calibrated simply by a single-time measurement using this proposed sensor.
In measurement, the microwave sensor is operated over 3.5 – 3.8 GHz frequency band. The Q value of the active SRR is increased by 22 times (from 49.7 to 1098), compared by the passive resonator. Therefore, the sensitivity of the liquid measurement is improved by 2.3 to 3.7 times. By applying this proposed sensor, the measurement errors of the concentration of the test liquid (acetone-water mixture) has the average error of 4.7 %. The proposed DA-SRR not only has the advantages of high sensitivity due to the enlarged Q value but also eliminates the errors by the dual-band correction technique to fulfill a high sensitive microwave sensor for the liquid permittivity measurement.

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