Research On UWB Notch Antenna And EBG Structure That Applied To Wearable System

The development of the wireless body area network(WBAN)technology has also promoted the development of the intelligent wearable devices,which makes it very convenient for people to collect and transmit information by using the wearable devices.As the most important devices for signals receiving and sending,antenna has become the key component of the WBAN communication system.The advantages of UWB communication technology are large bandwidth and low transmission power,which are helpful of improving the data transmitted rate and solving the energy of the battery.UWB communication technology has become the most promising technology for WBAN system.However,the spectrum of UWB system overlaps with other narrow-band communication systems.In order to avoid interference with other existing radio communication systems,it is necessary for band-notch antenna design.Due to the on-body operating situation,the safety of electromagnetic radiation should be carefully took into consideration.Electromagnetic Band Gap(EBG)could increase the gain and reduce the electromagnetic radiation when used as the antenna reflector.Thereby,the research on EBG structure that applied to wearable system is of great significance.Based on the basic design method of planar UWB monopole antenna,the performance parameters of antennas,including VSWR?gain?surface electric current and radiation pattern have also been studied.The performance parameters of antennas under bending situations have also been studied.The unit of EBG structure has been optimized and used as the reflector.A human body model is established to investigate the SAR under both situations of with and without EBG reflector.The research results are as follows:1.Two band-notch UWB antennas are proposed in this article.Both of them can filter out the signal of WiMAX and WLAN systems.The dual band band-notch UWB antenna operates at 2.9-10.7GHz,with band-reject characteristics within 3.2-3.9GHz and 5.1-6.0GHz frequency range.A triple band band-notch UWB antenna is proposed.This antenna operates at 3.0-10.8GHz,with band-reject characteristics within 3.2-3.9GHz?5.1-5.4GHz and 5.6-6.0GHz frequency range.The result shows that both antennas could work properly under bending situation with good robustness.2.Two wearable antennas based on EBG reflector have been proposed.The narrow band wearable antenna operates at 2.4GHz,while the UWB wearable antenna operates at 3.7-12GHz.Some investigations about the performance parameters of antennas under with and without EBG reflector situations are made.The peak gain of narrow band wearable antenna increases from 2.8dB to 6.3dB when using EBG structure as reflector,while the peak gain of UWB wearable antenna increases from 4.7dB to 9.6dB.Also,the radiation pattern towards human body generates side-lobe,which means the maximum radiated power has been decreased.The SAR is beyond safe range when not using EBG reflector.After adapting EBG reflector to wearable antennas,the SAR decreases rapidly and finally meets safety standards and design requirements of on-body operating situation.