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由于微波通过介质所产生的相移变化,在一定条件下,主要取决于介质的ε′,而与电导率σ关系不大,这就提高了微波的检测能力,因此,本文先经过理论分析,并确定采用一个经过校刻的精密移相器,通过微波电桥与待测的双口网络的相移进行比较,得到令人满意的效果。因此,理论分析和实验结果均表明,用微波相移法测定鲜牛奶掺水而引起的百分比浓度变化是一种行之有效的方法,它与上篇构成一套完整的用模值|S_(21)|和辐角arg S_(21)检测鲜牛奶掺杂掺水的测试办法。整个工作表明,采用微波技术及适当的测试系统,对鲜牛奶的掺杂掺水鉴别具有可行性。
Due to the phase shift caused by the microwave through the medium, under certain conditions, mainly depends on the dielectric ε ’, and the conductivity σ is small, which increases the detection ability of the microwave, therefore, this paper through theoretical analysis, And to determine the use of a precision engraved engraved phase shifter, through the microwave bridge with the dual-port network to be measured phase shift comparison, get satisfactory results. Therefore, the theoretical analysis and experimental results show that the microwave phase shift method to determine the change of the percentage concentration caused by the fresh milk mixed with water is an effective method, which constitutes a set of complete modulus values | S_ ( 21) | and arg S_ (21) and the test method for measuring fresh milk doping with water. The whole work shows that using microwave technology and appropriate test system, the identification of fresh milk doping water is feasible.