相消型介质参数变化测试传感器

为测量化学溶液由于温度、浓度等外在因素的变化而导致介电常数的微弱变化，设计了相消型介电常数微小变化测量传感器。该传感器依据幅度相同、相位相反的2路信号相消的原理进行设计。该装置主要包括1个同相威尔金森功分器和1个180o反相功分器，2个功分器用2条槽线相连形成2条支路，分别是参考支路与测量支路，待测物与参考物分别放在2条支路上。通过测量2条支路相消的情况来反映待测物与参考物之间介电常数的差异。仿真结果表明，与常规共面波导测量方法相比，该传感器在观测材料参数变化方面，其传输参数的幅值灵敏度提高了18 dB以上。

A cancel type sensor for measurement of permittivity changes

In order to measure small permittivity changes of chemical solutions caused by temperature and concentration,a cancelltype sensor is proposed. The device consists of an in-phase Wilkinson power divider and an out-of-phase power divider,and the two dividers are connected by 2 slot lines. Therefore, two branches called reference and test branch are formed respectively,on which the Material Under Test（MUT） and reference（REF） material are placed. The permittivity difference between the MUT and REF is reflected by measuring the cancellation of the two signals. Simulation results show that the sensor proposed can improve amplitude sensitivity of transmission parameters by more than 18 dB,compared with traditional Coplanar Waveguide（CPW） measurement.