An Ultrawideband Conformal Antenna at 433 MHz for Wireless Capsule Endoscope of Pediatric Patients

Wireless capsule endoscopy (WCE) systems are used to capture images of the human digestive tract for medical applications. The antenna is one of the most important components in a WCE system. In this paper, we propose a compact capsule antenna operating at the 433-MHz ISM band. The antenna conforms to the outer-wall of a small capsule module with dimensions of 19.5- -mathbf{mm} -times 10- -mathbf{mm}. A colon-equivalent tissue phantom and CST Gustav voxel human body model were used to numerically verify the operation of the capsule antenna. The simulation results in the colon-tissue phantom were then validated through in-vitro measurements using a liquid phantom. According to the phantom simulations, the capsule antenna has -10 dB impedance matching from 288 to 2200 MHz. The ultrawideband characteristic enables the capsule antenna to tolerate the detuning effects due to electronic modules in the capsule and due to the proximity of various different tissues in gastrointestinal tracts. While providing ultrawide operational bandwidth and sufficient radiation performance, the small size makes the antenna suitable especially for pediatric patients in addition to adults.