Study Of Wearable Antennas With Dual Communication Modes Of On-body And Off-body

Dual communication mode wearable antenna has attracted attention of researchers in recent years for its ability to achieve seamless transmission of information among on-body communication and off-body communication.According to the working mechanism,the existing dual-mode wearable antennas are divided into three categories,and an antenna is designed for each category in this thesis.The three antennas can be easily integrated on the surface of clothing or worn directly,and have good application prospects in wireless body area network.The specific work contents are as follows:(1)A dual-band dual-mode wearable antenna is designed.The antenna can be used in 2.4-2.4835 GHz and 5.725-5.875 GHz of industrial scientific medical band.The coaxial line feed is used to directly excite TM₁₁ mode of the upper circular patch to realize the off-body mode in the high frequency band,and the capacitive coupling excitation is used to excite TM₀₁ mode of the lower circular patch loaded with four short-circuit probes to realize the on-body mode in the low frequency band.The measured results show that the antenna has good dual band and dual mode characteristics.(2)A single band dual-mode reconfigurable wearable antenna is proposed.The antenna is designed based on a rectangular patch antenna and works in 2.4-2.4835GHz ISM frequency band.PIN diodes are used to control the connection of the rectangular patch and four grounding shorting pins,and the rectangular patch can be tuned to resonate in TM₀₀ and TM₀₁ mode respectively,so that the antenna can flexibly switch between on-body and off-body communication mode.Felt is used as the dielectric substrate on the side of the antenna close to the human body,which improves the wearing comfort effectively.The performance of the proposed antenna near human is measured,and the specific absorption rate is simulated.All the results prove the application potential of the antenna in wearable system.(3)A dual-mode broadband wearable MIMO antenna is presented.The antenna works in 5.15-5.825 GHz wireless local area networks frequency band,and two layers of dielectric substrates are made of polydimethylsiloxane(PDMS)and felt,respectively.A circular patch with parasitic concentric rings in the lower layer is used to realize the broadband on-body communication mode,and a rectangular patch with a pair of asymmetric slots in the upper layer is used to realize the broadband off-body communication mode.Through the structure of separating ground,the isolation between ports is improved by 7 d B.The measured results show that the proposed antenna can be effectively applied to wearable MIMO system.