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来改善无线胶囊内窥镜的性能。通过阵列天线技术可以提高传输的体内图像的质量，这也可以有效地抑制体内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配置及其可变天线权值，建立了考虑互耦效应的接收阵列天线系统的理论模型。并对具有最大接收功率的阵列天线和具有最大发射方向性增益的阵列天线进行了对比研究。基于最小均方误差准则确定接收功率最大的阵列天线的权值。通过比较研究，得出了近距离自适应阵列天线所需满足的必要条件，并根据TDL-AAA的时空均衡特性，选择TDL-AAA作为近距离自适应阵列天线系统。该均衡器对于在密集多径环境下减少天线单元的数量是非常有效的。我们已经推导出所需的天线元件和抽头级的基础上的迫零标准。

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.