Receiving Uwb Antenna for Wireless Capsule Endoscopy Communications

Abstract

Wireless capsule endoscopy systems utilize a combination of hardware and software devices to ensure the healthcare of a human being. In praise of involved antennas in the overall medical system design, UWB (Ultra-Wideband) range occupies the highest ranks in the literature. The low-band of UWB is regarded as the best frequency range, within the approved standards, to realize the better transmission of captured medical images by the capsule inside the SI tract, in terms of high resolution and low-path loss. A variety of passive capsules have been designed and made available in the literature, while the accurate design of the corresponding on-body antenna is lagging. For this purpose, this paper provides an extended study of a recently published on-body antenna operating at 3.75-4.25 GHz band. The measured antenna realizes good directivity of 5.78 dBi and 9.50 dBi towards the body without and with the cavity, respectively. The direction of the proposed on-body antenna beam is targeted to be mounted on the body surface. On-body simulations were run with CST Microwave Studio by involving an abdominal multi-layer model, and followed by navel and back areas of the voxel model to predict the antenna behavior close to different lossy body environments. Later, the antenna structure was measured next to a real human abdomen. Simulation results reveal that the proposed antenna with or without the cavity enables enhanced in-body communication when mounted on the abdomen with less path loss. This is supported by the low power totaling 20 dB at the SI (Small Intestine) tract. Furthermore, on-body measurements confirm the good antenna performance. Consequently, the planar compact antenna is regarded as a good on-body candidate for wireless capsule endoscopy systems.

Low-UWB Antennas in Vicinity to Human Body

“…The antenna used in these investigations is a Low-UWB cavity-backed antenna presented first time in [6]. The antenna is operating at Low-UWB band defined by BAN part of IEEE 802.15.6 standard.…”

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

“…The antenna is originally introduced in [27]. Detailed description of the antenna and its properties can be found in [27] and [28] and initial radio channel evaluation studies for capsule endoscope communications can be found in [18]. As a reference antenna, we use the on-body antenna designed for capsule endoscope communications introduced originally in [26].…”

“…With this antenna location and antenna-body distance, the presence of the human body seems to cause a notch in Ring antenna's radiation pattern towards this capsule location in the middle of the SI. Details of the antenna radiation patterns for Ring antenna can be found in [27] and [28]. Power flow representation presented in Fig.…”

“…However, the main reason for the differences between the S22s obtained with different voxel models is the differences between the thicknesses of the tissues between. Reference [28] present reflection coefficients simulated with layer models having different thicknesses for the fat and muscle layers. In that study case, difference between the layer models resembling the ''lean'' and ''overweight'' cases is minor.…”

“…Thus, there are several WBAN channel models and propagation studies presented in the literature for wearable and implant communication systems in the human abdomen area [5], [6], [8]- [18]. Furthermore, the research in antenna design, both for capsule antennas as well as for on-body receiver antennas, has been active recently [19]- [28]. Channel characteristics between the capsule antenna and on-body antenna is studied, e.g., in [5], [6], [19].…”