QUADRATURE DETECTION IN THE LABORATORY FRAME
QUADRATURE DETECTION IN THE LABORATORY FRAME
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DOI：
10.1002/mrm.1910010305
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发表时间：
1984-01-01
影响因子：
3.3
通讯作者：
SANK, VJ
中科院分区：
文献类型：
--
作者：
HOULT, DI;CHEN, CN;SANK, VJ
提出了一种实验室正交检波理论。结果表明，正交检测所需的两个正交线圈系统的几何形状与鞍形线圈所使用的几何形状完全不同，并且在传输时产生的B1场的均匀性略好。相反的正交相移所需的传输和接收的强调，并主张使用正交混合作为一个简单而廉价的手段接口的发射机，探头，和放大器。实验结果证实了理论预测，并表明，高达40%的灵敏度提高和发射机功率的两倍减少是可能的，特别是在那些情况下，其中的样品是导电的，即成像的人类和体内光谱。
A theory of quadrature detection in the laboratory frame is developed. It is shown that the geometry of the two orthogonal coil systems needed for quadrature detection is radically different from that used with saddle‐shaped coils, and that the homogeneity of the B1field produced upon transmission is marginally better. The opposing quadrature phase shifts needed for transmission and reception are emphasized, and the use of a quadrature hybrid is advocated as a simple and inexpensive means of interfacing the transmitter, probes, and preamplifier. Experimental results are presented which confirm the theoretical predictions, and show that up to a 40% improvement in sensitivity and a twofold reduction in transmitter power are possible, particularly in those instances where the sample is conductive—namely, imaging of humans and in vivo spectroscopy.