Design Of Wearable Antenna For Wireless Body Area Network Based On AMC Structure

In recent years,with the continuous innovation of wireless communication technology,wearable antenna for wireless body area network has been widely developed and applied,which brings great convenience to the lives of human beings,and has important application value in medical,military and other fields.In order to meet the application requirements of wearable antenna,it gradually develops toward miniaturization,low profile,light weight and high security.The complex human electromagnetic environment also increases the difficulty of the wearable antenna design,raising higher index requirements for reducing the coupling between the antenna and the human body.This paper is devoted to the research and design of the wearable antenna for WBAN based on the index of integrated wearable antenna and the theory of artificial magnetic conductor(AMC)structure.The main work is as follows:1.A circular ring slot single-frequency wearable antenna based on the L-shaped slot AMC structure is designed and proposed for the ISM 2.45 GHz band.The upper antenna of the antenna system combines circular slots with asymmetric slots,which expands the working bandwidth of the antenna.In order to reduce the coupling between the antenna and the body,L-shaped slots are etched around the traditional mushroom-type AMC structure,which reduces the size of the AMC unit.The 2?2 array of the AMC structure is loaded under the antenna,and the radiation of the backward radation is reduced by the characteristic of ±90° in-phase reflection.The gain of antenna increases to 7.47 dBi,achieving the front-back ratio greater than 20 dB.In addition,the bending stability and radiation safety of wearable antenna system are studied in this paper,the SAR(Specific Absorption Rate,SAR)< 0.15 W/kg,lower than the international safety standards.For further verification,the measured results show a strong agreement with the simulation,satisfying the design requirements of indicators.2.In order to make full use of ISM band and improve utilization of the channel,a Ushaped dual-band wearable antenna based on miniaturized AMC structure is proposed.By adjusting the relationship between the total length of the symmetrical U-shaped patch and the wavelength,the upper dual-frequency monopole antenna resonates at 2.45 and 5.8GHz,respectively.Aslo,the size of the antenna is reduced by folding the patch multiple times.Meanwhile,in order to meet the requirements of low radiation and high gain for wearable antenna,a dual-frequency artificial magnetic conductor structure with miniaturization characteristics is proposed.The composed antenna system can cover 2.4~2.48 GHz and 5.725~5.85 GHz of ISM frequency band.Owing to the addition of AMC structure,the backward radiation is effectively reduced,and the forward gain at low frequency and high frequency increase to 6.43 dBi?7.75 dBi,respectively.When the antenna operates on the human body,it has stable performance under the bending condition and high security,meeting the practical application requirements of wearable antenna.In summary,the two wearable antennas proposed in this paper meet the development trend of miniaturization,high security and low cost,sytisefying the practical application requirements of ISM band in WBAN.