Investigation on an enhanced S/N array antenna system applied to the battery-free wireless capsule endoscope within a CCD camera

本研究的目的是利用自适应阵列天线技术提高无线胶囊内窥镜的性能。阵列天线技术可以提高传输的内层图像的质量，并且可以有效地抑制内层肌肉和骨骼的负面影响。其中最重要的研究问题是如何确定天线的分配和各天线的可变权值。建立了考虑互耦效应的接收阵列天线系统的理论模型。并对最大接收功率阵列天线与最大发射指向性增益阵列天线进行了对比研究。基于最小均方误差（MMSE）准则确定接收功率最大的阵列天线权重。通过比较研究，得出了近距离自适应阵列天线的必要条件。此外，我们选择了抽头延迟线自适应阵列天线（TDL-AAA）作为最合适的自适应阵列天线系统，因为TDL-AAA是一个时空均衡器。在密集多径环境下，该均衡器可以有效地减少天线单元的数量。我们根据零强迫准则推导出所需的天线单元和分接级数。

The purpose of this research work was to improve the performance of wireless capsule endoscopes by adaptive array antenna technologies. Quality of transmitted inner body images can be improved by array antenna technologies and this is also effective to suppress the negative effects by inner body muscle and bone. Especially, the most important research problem is how to determine antenna allocation and their variable antenna weights.We have established the theoretical model of a receiving array antenna system considering mutual coupling effect. Furthermore the comparative study between the array antenna with maximum receiving power and the array antenna with maximum transmitting directivity gain has been performed. The weights of the array antenna with maximum receiving power were determined based on Minimum Mean Square Error (MMSE) criteria. By the comparative study, we have arrived at the necessary condition which is required in closely spaced adaptive array antennas.Furthermore, we have chosen Tapped Delay Line-Adaptive Array Antenna (TDL-AAA) as the most suitable adaptive array antenna system because TDL-AAA is a spacial and temporal equalizer. This equalizer is very effective to reduce the number of antenna elements under a dense multipath environment. We have derived the required number of antenna elements and tap stages based on the zero forcing criteria.