Research On The Terminal Antenna Of The Beidou Island Monitoring System

With the development and improvement of the Beidou satellite navigation system,Beidou short message communication has been more and more used in natural disaster warning,disaster relief and other aspects for its convenience and reliability.The monitoring system in romote areas and unattended,once the power failure or be stolen or other accidents,it will lead to the monitoring can not work properly,may cause greater losses.Therefore,we need to install an alarm terminal in these island monitoring system,and report to the command center timely.So far,we monitor the status of the monitoring system in remote areas through the GPRS or 4G,but the GPRS or 4G signal in remote area is weak,can not be timely and realiable to transmit information,and the cost of the leased line is too high,so we consider design an alarm terminal of island monitoring system based on Beidou short message communication.In this thesis,considering the demand of the island monitoring system,the design block diagram of the monitoring system based on the Beidou satellite navigation system is given.The Beidou navigation system in the alarm terminal bear the function of positioning and short message communication,we selected the suitable Bei Dou positioning and communication module TM8260,and we put forward the needs of antenna according to the performance parameters of TM8260 and the general specification of Beidou short message terminal and navigation terminal.The antenna in the system needs to meet the needs of RDSS and RNSS,ultimately we design a three layers stacked microstrip antenna covered B1,L,S band.Based on the basic theory and analysis methods of the microstrip antenna and the circular polarization method of microstrip antenna,we decide dual fed for B1,L and single fed for S with corner cut.Through the comparison of power divider,we use Wilkinson power divider for the feed network of B1 and L.The simulation results meet the requirements,and left a certain margin.Finally,we take into accout that special circumstances of the monitoring system is relatively small,and we send people has been in the command center guards are more wasteful labor costs,so we need a short message communication of Beidou handheld terminal,so we design a compact dual layer microstrip antenna for the Beidou handheld terminal.It can achieve the Beidou short message communication function,and positioning function realized through Bei Dou B1&GPS L1,also the receiving position amplifying circuit integrated on the floor of the microstrip antenna,reduce the noise figure of the system.