Design Of Miniaturized Wearable Microstrip Antenna

With the popularity of wearable smart devices and the rapid development of wireless communication,the importance of wearable antennas with beautiful,intelligent and portable features is increasing.This paper summarizes the research status of wearable antennas.Then the dielectric constants of several textile materials used in wearable antennas were tested.This paper designs two flexible wearable microstrip antennas,they used the textile materials that measured the dielectric constant as the substrate,and worked at 2.42GHz~2.484 GHz,5.725GHz~5.85 GHz band.After that,two types of wearable microstrip antennas were designed for the 27.5GHz~28.35 GHz band.The performance of antennas placed on the human body was tested and analyzed,the development prospect of these antennas were prospected.The main research contents as follows:In order to improve the portability of the designed antenna,this paper choose denim as antenna substrate,and select copper foil tape as a radiating element,then design and manufacture two kinds of dual-band flexible wearable microstrip antennas(2.45 GHz and 5.8 GHz).The winding folded wearable microstrip antenna adopts the method of bending the radiation part.The simulation results show that the dominant resonant frequency is 2.45 GHz and 5.8GHz,and the bandwidths of-10 dB is 2.33GHz~2.68 GHz,5.59GHz~5.98 GHz,respectively.The performance of the antenna is consistent with the theoretical calculation,they all can meet the design requirements.Put the antenna in the human body environment,get the simulation and measurement results of difference is not big,therefore,the antenna performance is not greatly affected by the human body.The multi-branch flexible wearable microstrip antenna has greatly reduced the size of the antenna while obtaining the dual-band antenna.The simulation results show that the dominant resonant frequency is 2.45 GHz and 5.8GHz,and the bandwidths of-10 dB is 2.3GHz~2.55 GHz,5.55GHz~6.6GHz,respectively.The antenna is processed and tested,the measurement results are consistent with the simulation results,they both can meet the design requirements of dual-band.When the antenna is placed in the human environment,the simulation calculation and actual test are carried out.The measured S11 diagram and the simulation result are consistent,and all of them covered the frequency band.With the rapid development of 5G communication and the miniaturization of wireless devices,it is necessary to study the smart wearable antennas with higher frequency band and smaller volume.This paper selects 5G authorized frequency band(27.5GHz~28.35GHz)specified by the FCC to design two wearable microstrip antennas that work in the 28 GHz frequency band and process them into antenna objects.A CPW feed wearable microstrip antenna,by using coplanar waveguide feed,the return loss of the antenna is further reduced and the antenna performance is improved.The simulation results show that the dominant resonant frequency is 28 GHz,and the bandwidths of-10 dB is 27.40GHz~28.66 GHz,then the antenna is processed and tested,the results show that the measurement results are consistent with the simulation results,they both can cover the authorized frequency band of 28 GHz in the U.S.FCC.Placed the antenna in the human body model,the simulation results show that the return loss of this antenna in human model is basically consistent with free space,which indicates that the antenna has good performance in the near human characteristics.A wearable microstrip antenna with a rectangular ring groove on the back,by using slot technology,the miniaturization design of antenna is realized.The simulation results show that the dominant resonant frequency is 28 GHz,and the bandwidths of-10 dB is 27.3GHz~28.68 GHz.The antenna is processed and tested,and the measurement results are consistent with the simulation results,they both can cover the authorized frequency band of 28 GHz in the U.S.FCC.The characteristics of the antenna near the body are also verified,it shows a good match between the two conditions(on-body,in the free space),that is to say,the human body has a small impact to the performance of the antenna.The proposed antenna has good application prospect in intelligent wearable field.