Meaney Paul M, Shubitidze Fridon, Fanning Margaret W, Kmiec Maciej, Epstein Neil R, Paulsen Keith D
Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA.
Int J Biomed Imaging. 2012;2012:697253. doi: 10.1155/2012/697253. Epub 2012 Apr 10.
Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.
微波成像技术容易受到来自不需要的多径信号的信号干扰。近场系统尤其容易受到影响，因为信号会在成像区域内或边界上的结构物体上散射和反射。当产生表面波并有可能沿着发射和接收天线馈线以及其他低损耗路径传播时，这些问题会进一步加剧。在本文中，我们分析了由表面波效应产生的多径信号的影响。具体而言，使用一个位于耦合流体罐底部不同高度处的近场微波成像阵列进行了实验。还评估了流体中具有不同馈线长度的天线阵列。结果表明，表面波在测量阵列上最长的传输距离上会干扰接收到的信号。然而，只要馈线长度足够长，与发射/接收天线尖端到成像罐底部的距离无关，表面波效应就可以消除。理论预测证实了实验观察结果。
