Study On The Textile Substrate Tag Antenna Based On Conductive Ink

As a kind of wearable devices with good application in the Internet of things,the fabric substrate RFID tag has broad application prospects.However,when the RFID tag is twisted or placed on human body,its performance will be changed,and the change of tag performance may limit the scope of the tag.Therefore,it is of great significance to study the performance of fabric substrate RFID tag antenna in the case of deformation and placement of human tissue.This paper researched the performance of the fabric substrate wearable RFID tag antenna with relative dielectric constant testing,tag antenna tiling,bending and torsion and placed on the human arm to provide reference for the design and application of fabric substrate RFID tag antenna.Research methods include modeling,simulation and measurement.Main research contents and conclusions are as follows:(1)Using vector network analyzer,the relative dielectric constant was calculated through the resonance method.By simulation and optimization,tag antennas with good performance were got,and the specific parameters were calculated in HFSS which provide a reliable basis for the preparation of real antenna.(2)Through the simulation,it is found that the bending has little influence on the performance of the tag antenna and the torsion has great influence on the tag antenna.Bending deformation without destroying the antenna' equilibrium structure,the antenna still has good behavior.Torsion deformation with destroying the antenna' equilibrium structure led to the mismatch of antenna and chip.(3)The fabric substrate RFID tag antennas respectively with the shape of tile,bend and torsional were attached to the human arm and the performance changed a lot.(4)RFID tag antennas and tags were manufacture with screen printing technology.Then the balanced-unbalanced converter is designed and it was used to measure the impedance.With the method based on S parameters,the impedance values of the fabric substrate tag antennas were obtained.Then the impedances of the tag antennas with tiling,bending and torsional status attached on the arm were measured.The measurement results and simulation results have some differences,but they all showed that the impedance of the antenna changed,and it is inconsistent with the tag chip.At last the maximum reading distances of the tag were measured with RFID reader.