Research On Antenna Based On Wireless Power Transfer On Human Body Surface

With the continuous development of body area network related technologies,the trend of body area network grouping is becoming more and more obvious,and 6 G communication technology is driving the formation of body area network.In the future,these technologies will be integrated into the human body to interconnect the various communication modules of the body area network,and power supply will then become a necessary issue.To this end,this paper investigates antenna technology that transfers kinetic energy wirelessly,with the following main research elements:(1)The concept of wireless power transfer on the body surface is proposed.A realistic non-uniform solid-state electromagnetic simulation model is investigated based on the comparable characteristics of the arm diameter and the wavelength of 5.80 GHz in the ISM band.Based on this,the wireless power transfer concept is extended to the body surface transmission study of body area networks to investigate the performance of wireless power transfer between two identical all-fabric Yagi antennas placed on the arm and to accurately evaluate the transmission efficiency.(2)Study of a periodic structure-loaded directional button antenna.For the top dielectric loaded button antenna,the directional radiation of the button antenna in the 5.80 GHz ISM band is achieved by loading a 3×3 cell double T-shaped artificial magnetic conductor(AMC)structure at its microstrip feed line end;and a 2×3 cell AMC structure is investigated to reduce the antenna profile based on the effective reflection region of the metamaterial cell.Simulations and measurements show that the method not only reduces the body specific absorption rate(SAR value),but also improves the gain and transmission efficiency.(3)Research into easily integrated miniaturised directional button antennas.A technique for miniaturising antennas at conventional high frequencies is used to study the loading of AMC structures in the 24 GHz band in the ISM band to achieve directional radiation from a button antenna.The height of the antenna is only 2.2 mm after the loading of 3×3 periodic units,which is a significant reduction compared to 10 mm at 5.80 GHz.Simulation studies show that the performance of the directional button antenna at high frequencies is minimally affected by the arm.(4)Study of low-profile directional button antennas based on non-periodic resonant structures.To address the above mentioned characteristics of wireless power transfer at 5.80 GHz and 24 GHz,a new non-periodic resonant structure loading technique at 5.80 GHz is investigated to reduce the profile of the antenna.It consists of a dielectric layer and two metal layers with square open rings symmetrical along the monopole.By adjusting the monopole size and the parameters of the new loading structure,it is possible to achieve directional radiation with a button antenna profile of 6.5 mm and a gain reduction of only about 0.6 d B compared to the loading of a 3×3 periodic units.