Two-stage radio-frequency interferometer sensors.
Two-stage radio-frequency interferometer sensors.
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DOI：
10.1063/1.4934622
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发表时间：
2015-10
影响因子：
4
通讯作者：
Jeffrey A. Osterberg;Pingshan Wang
中科院分区：
文献类型：
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作者：
Jeffrey A. Osterberg;Pingshan Wang
我们表明，简单的射频（RF）干涉仪可以有慢波正群延迟（PGD）或负群延迟（NGD），以及超光速传播（SP）的地区，由于相消干涉过程。这些属性很容易调谐，这使得RF干涉仪在具有NGD和SP机制的系统中是独一无二的。与单级参考干涉仪相比，包括在第二级的被测材料路径中的第一级干涉仪的两级干涉仪布置具有显著提高的灵敏度。采用基于功率分配器的第一级，在其最大NGD频率下，频率灵敏度提高高达7倍。使用基于正交的第一级，灵敏度增加多达20倍。在PGD和SP频率区域也观察到灵敏度改善。
We show that simple radio-frequency (RF) interferometers can have slow-wave positive group delay (PGD) or negative group delay (NGD), as well as superluminal propagation (SP) regions, due to a destructive interference process. These properties are easily tunable, which makes RF interferometers unique among systems that have NGD and SP regimes. A two-stage interferometer arrangement, which includes a first stage interferometer in the material-under-test path of a second stage, has significantly improved sensitivity in comparison with a one-stage reference interferometer. With a power divider based first stage and at its maximum NGD frequency, the frequency sensitivity improvement is as high as 7 times. With a quadrature based first stage, the sensitivity is increased by as much as 20 times. Sensitivity improvements are also observed at PGD and SP frequency regions.