Study On Wearable Antennas And Propagation For Body-Centric Wireless Communications

In recent years, body-centric wireless communication is paid more and more attention by researchers. It could be used in some specialized occupations, such as fire fighters, military and monitoring the aged. One of the dominant research topics for body-centric communications is wearable, textile-based antennas because it could be easily worn on body and integrated into clothes.The main work of this paper is as follows:1. This paper focuses at the study on the electromagnetic properties of e-textiles for wearable antennas applications, mainly studies the electromagnetic properties of e-textile cell and calculates the basic resistance and inductance in a grid as well as discusses the influences of different woven densities and e-textile materials to antenna performances. We studied the surface current distribution of e-textiles, founding that the surface currents are mainly parallel to the feed line, and has the same orientation. In addition, to study the influences of different e-textile materials to antenna performances, we adopt four different materials to design and fabricate four microstrip patch antennas. The conclusion is that metal plated woven fabric could be used as metal plane to design antennas while non-woven fabric shows distinct differences.2. Proposed an easy method to measure permittity of the substrate, which is measuring the resonance point of antennas to evaluate the actual permittity of the textile adopted.3. Study on the radiation characteristics of textile antenna and propagation characteristics of electromagnetic waves near human body, as well as body-centric wireless communication channels.4. In order to achieve an antenna with circular polarization in the2.45GHz ISM band, we designed a square-ring microstrip antenna with truncated corners using textile materials, which could be easily worn on human body. We also simulated the antenna performances when it was placed at different distances to the human body. Moreover, special attention was devoted to the antenna performance in the bent situation. Furthermore, the circular polarization analysis enhanced its operability. Simulations indicated that SAR values compliedwith the basic restrictions for the general public.5. Design a planar monopole UWB wearable antenna. It works at3.1GHz-10.6GHz. To evaluate the characteristic of the antenna worn on human body, we model the human body as a three-layer phantom including1mm skin,3mm fat and10mm mulcle. Then we assume the human body as dispersion media, and put the antenna at different distences to the human body. The conclusion is that when the antenna is put on the vicinity of the human body, its performance of the return loss and radiation decreases, however, it could work in the body-centric wireless communication as well.6. We design a CPW-Bowtie Antena, Body dipole antenna and Cylinder ring dipole antenna utilizing the geometry of human body.