WBAN Channel Characteristics Between Capsule Endoscope and Receiving Directive UWB On-Body Antennas

This paper presents a study on the ultra wideband (UWB) radio channel characteristics between a capsule endoscope and a directive on-body antenna in different parts of the small intestine. The study is conducted using a finite integration technique (FIT) based electromagnetic simulation software CST Studio Suite and four of its anatomical voxel models. The capsule endoscope model is set inside different areas of the small intestine of the voxel models. A recently published directive on-body antenna designed for in-body communications is used in the evaluations. The obtained frequency and time domain channel characteristics are compared with previously published results with another directive on-body antenna designed for capsule endoscopy communications. Power flow presentations are used to understand differences obtained with two on-body antennas. Different rotation angles of the capsule are also considered in this study. It is found that channel characteristics vary remarkably depending on the antenna location in the small intestine and location of the on-body antenna. Thus, the on-body antennas should be located carefully to ensure coverage over the whole intestine area. Path loss does not only depend on the distance between a capsule and the on-body antenna but also on the tissues between the capsule and on-body antennas. Obviously, the antenna patterns have clear impact on the received signal's strength. Furthermore, orientation of the capsule affects also strongly impact when linearly polarized antennas are used.