Design And Research Of RFID Fractal Antennas For Coal Mine Monitoring Systems

With the constant development of wireless communication,RFID technology has been widely used in all kinds of specific application areas.Currently,all kinds of coal mine accidents have occurred.Therefore,to research a new type of RFID system for coal mine is very important so as to keep an accurate record of the number of miners,to protect the safety of miners and to ensure the rescue measures to be carried out successfully.As a vital and integral part of the system,RFID antennas have attracted much attention,and the design is very urgent and significant.In fact,the development of RFID antennas is of theoretical significance and practical value to the RFID system.Firstly,a brief introduction to the RFID technology is given,the operating principle of RFID system and the hotspot of research are described,and meanwhile the technical specifications and investigating status of antenna in RFID system are analyzed and discussed.And then,according to the environment of the underground coal mine and the working characteristics of RFID system,suitable fractal structures are chosen for designing the tag and the reader antennas.Finally,the simulations,optimizations, fabrications and experimental measurements of the RFID antennas are done.The author's contributions in this thesis include following aspects.(1)According to the analysis and research of the attenuation of the electromagnetic waves in the mine tunnel as well as the requirement of no explosion with equipment,we choose 2.4GHz as the system frequency.(2)A new fractal printed antenna with compact structure,small size and good performance is designed for RFID tag.Firstly,the radio frequency module with its matching circuits is given,and the requirements of RFID tag antenna are presented. And then,the structure designed for tag antenna is obtained through the simulations of printed inverted F and Hilbert fractal monopole antenna.Finally,the printed Hilbert inverted F antenna is simulated and optimized by Ansoft HFSS.(3)About the design of reader antenna,the requirements are presented firstly,and then an improved fractal structure is given.By using coaxial and aperture-coupled technology in simulation,it is found that the later antenna is more suitable for the personnel position system on the bandwidth requirement.(4)The experimental samples are manufactured according to the design parameters of RFID antennas,and the resonant characteristics and gain of the above samples are also tested by using the existing experimental conditions of school laboratory.The experimental results meet the practical requirements and the measured data agree with the calculated results.Finally,a simple measurement is done for the manufactured antennas by using the corridor model to simulate the working condition of coal mine tunnel.In this dissertation,the RFID fractal tag antenna has been analyzed and designed for coal mine applications.Due to its compact structure,small size,predominant performance and low cost,it is also suitable for such applications which need lots of tags,such as container automatic identification system and no stop toll collection system.