Dual band textile antenna on artificial magnetic conductor for on-body communication applications

Abstract

The integration of wearable devices on human body in Wireless Body Area Network (WBAN) offers new favourable and assistances. The properties of human body causes high transmission loss in the wearable antenna. In WBAN, the antenna and the artificial magnetic conductor (AMC) is needed to be flexible and comfortable to wear. Efficient wireless networking system depends on reliable tranmission between antennas. Textile dual-band AMC is developed as a ground plane to improve wireless on-body transmission. It offers clear on-body transmission path with increased antenna’ performances. The proposed wearable antennas and AMC jacket are purely textiles, which makes it convenient for wearable communication. In this thesis, the performance of single-band and dual-band textile antenna with and without dual-band AMC are studied in terms of radiation characteristic, reflection coefficient and transmission path. The antennas and AMC are designed to be operated at 2.4 GHz and 5.8 GHz. From the experiment, the characteristics of textile dipole antennas are altered when placed on the AMC sheet. The radiation characteristics and bandwidth of the antenna for both frequencies follow the AMC behavior while the gain of the antenna is increased about 4 dB. The radiation pattern of the antenna becomes directive when placed on the AMC sheet. Then, several experiments of transmission between antennas are conducted to test the reliability of the communication. Different antenna’ orientation and placement are considered. A maximum gain of 15 dB is achieved when the antenna is placed in a horizontal and vertical orientation. Finally, three types of jackets which are normal, ground and AMC jackets are fabricated. The transmission between antennas on those jackets are compared. Significant transmission enhancement is observed when both antennas are placed on the AMC jacket and vice versa to when the antennas are placed on the ground jacket. It shows a 15 dB S21 transmission improvement compared to transmissions on the normal jacket. Moreover, the AMC jacket offers outwards directional radiation pattern from human body with high gain. In addition, the textile bending measurement is also investigated. It is found that the textile bending gave no significant effect to the antennas and AMC sheet performance. In conclusion, the dual-band textile antenna and dual-band AMC jacket are successfully developed.