Relations of Input Resistance Increases and Current Distributions of a Normal-Mode Helical Antenna in a Human Body Condition

For capsule endoscopy applications, Normal-Mode Helical Antennas (NMHA) are trying to be used. However, when antenna was placed in a human body, it was reported that an antenna efficiency was decreased owing to increase of input resistance. To analyze the input resistance increase is important. In this paper, the relations of input resistance increases and current distributions on an antenna are examined. It is concluded that the input resistance increases have very close relation with decreases of current distributions.