| At present,the aging population problem in China becomes increasingly serious,which is possibly to cause a lack of healthcare resources in the near future.Because the portable physiological monitoring system is capable of providing timely telemedicine assistance at home for the elderly patients,the demand for wearable medical device will increase sharply.As an important part of the wearable device,wearable antenna is worthy to be studied in depth and explored for valuable applications.In addition to the medical applications like physiological monitoring,wearable antennas have even more prospects in various research fields such as military affairs,firefighting,exploration and entertainment.In this paper,a systematic study on the textile wearable antenna is conducted mainly in terms of three aspects as follows.Firstly,for antenna’s material and fabrication,the polyester-cotton fabric is chosen as the flexible substrate,and the silver paste is chosen as conductive material.Processed by advanced screen printing technique,high-precision,lightweight and comfortable innovative textile antenna design is achieved.Secondly,for antenna design,2.45 GHz is set as the working frequency,considering wearable antenna’s connection with other devices in the wireless body area network(WBAN)application.In addition,taking into account the research interest of multi-frequency transmission in communication systems,the dual-band antenna design at 2.45 / 5.8 GHz has been completed.Moreover,in order to improve the antenna performance,two kinds of artificial magnetic conductor(AMC)unit are designed respectively for both the single and dual band antennas.They can reduce the radiation toward the human body as well as increase the gain in positive path while the antenna is working on the body surface.Great efforts have been made to reduce the size of the AMC unit,and as thin as less than 1 mm overall antenna thickness has been reached.However,due to the narrow bandwidth after loading AMC,antenna is sensitive to its operation frequency.But it still has good radiation performance at the resonant frequency.Thirdly,for antenna measurement,the relative permittivity of the polyester-cotton fabric was measured by the approach of using the open-ended coaxial probe.Such data provide reference for future textile antenna’s design.Furthermore,a series of methods have been employed to enhance the connection between the antenna and the coaxial cable during the measurement,such as adopting the PMI foam as the support,modifying the SMA connector’s structure,and applying the conductive silver adhesives.The wearable antenna proposed in this paper possesses the advantages of comfort,safety and portability in the practical applications.Moreover,it is outstanding for high precision and low cost of screen printing processing.Our results are promising for further optimization and application of the textile antenna,and can be taken the foundation for further development of functional wearable devices. |
