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

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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.