Wideband antenna design and sar comparison for electronic capsule endoscopy

In this study, a flexible loop antenna is presented for wireless capsule endoscopy system (WCEs). Dimension of the antenna is 27×13 mm
²
, and polyimide with a thickness of 0.05mm is used as the substrate. Simulation values of return loss, gain, radiation patterns and SAR at different parts of human body were evaluated based on CST microwave studio simulation. Simulation results indicated that resonant frequency of the antenna was 402MHz, the bandwidth achieved 350MHz, which covers the MICS (402-406MHz) band and ISM (433-434MHz) band, and an omnidirectional pattern reached a maximum gain of -32.3dBi at 402MHz. When the input power was 1 watt, the peak 1-g SAR is 340W/kg in the muscle, 368W/kg in the stomach, and 546W/kg in the small intestine. Measurement results in a whole pork showed a good agreement with the simulated results.