Antenna Design For Wireless Body Area Networ

In recent years,due to the frequent occurrence of gastrointestinal diseases,wireless capsule endoscope systems have been widely used to monitor symptoms in the human body,providing clearer image display and easier operation than other technologies.In order to further improve the transmission quality of the antenna,this thesis has designed a dual frequency dual mode wearable relay antenna operating in the 403 MHz frequency band for in-body mode and the 2.45 GHz frequency band for off-body mode.Zero-order resonant antenna insensitive to human characteristics is used for in-body mode,and circular patch fed by slot is used for onbody mode.The effectiveness of the antenna structure has been verified by simulating the performance of the antenna in the human body.At the same time,a spiral antenna operating at403 MHz was designed,and its working environment in the capsule endoscope system was simulated to achieve an omnidirectional pattern.With the progress of technology,the research and production of wearable intelligent devices on the human body surface is in a booming stage.In order to simplify the information transmission between various devices on the body surface and between the body surface and external devices,and improve its transmission quality,this paper proposes a circularly polarized wearable antenna operating in the 2.45 GHz band for on-body mode and the 5.8 GHz band for off-body mode.The on-body mode in this design forms a horizontally polarized antenna through an array of four arc dipoles,and uses a ring antenna as a vertically polarized antenna.The two antennas are connected through a 3 d B coupler to achieve a 90° phase difference between the two under the same gain,and finally synthesize an omnidirectional circularly polarized antenna.The off-body mode of this design is to create a square slot in the middle of the elliptical patch,introduce perturbation,form circular polarization,and realize directional radiation.