The helical antenna for the capsule endoscope

In this paper, a helical antenna for a capsule endoscope is designed. To encase the system in a small capsule module and to obtain omni-directional radiation pattern for detecting the transmitted signal independent of the transmitter positions, and to obtain wide bandwidth, a small sized normal mode helical antenna whose end is connected to the ground is designed. The diameter and the height of the helix are 8 mm and 5.6 mm, respectively. Measured results show that the antenna has 32 MHz bandwidth for VSWR<2, and an omni-directional radiation pattern.