Nearfield radio link of normal mode helical antenna for wireless capsule endoscopy

Abstract

Wireless capsule endoscopy is designed to monitor the physical data from inside human stomach and gastro intestine tract and transfer data to the receiver device. Normal mode helical antenna that has high efficiency at a small size is selected for WCE. To clarify the radio wave communication link budget in the dielectric environment is crucial. In this paper, NMHA for WCE system at 402 MHz along with a link budget analysis is presented. The transmitter uses NMHA embedded in a cylindrical phantom mimicking human stomach tissue, whereas the receiver uses another NMHA located outside the body. The NMHA dimension of height and diameter are 18 mm × 11 and 37 mm × 18 mm respectively. Through this study, a novel method of analytical equations for the radio wave communication link in human body are derived. From the good agreement between simulated and measured S21, the effectiveness of derived equations is ensured.