The Key Technologies In Photonics-Assisted Broadband RF Transceiver System

With the rapid development of wireless communication technology in the world today,the requirements of RF transceiver system are getting higher and higher,Not only requires the ability to support high-bandwidth,high sensitivity,also requested its reach as small as possible,as light weight,low power consumption as well as low cost as possible a wide range of requirements.Faced with this challenge,this paper applies microwave photonics theory and practical experience to analyze the problems encountered in wideband phased array radar systems.ROF links are used to give the broadband microwave signal which modulated on the light a true time delay,in order to achieve photonics-assisted broadband RF transceiver system.In this paper,the fundamental components of microwave photonics-Radio over Fiber(ROF)link are analyzed.The influence of the performance on the gain,noise figure and spurious-free dynamic range is analyzed,and discussed the link index of the relevant test methods to ensure the correct selection and performance testing of the system in the further research.Then the beamforming principle and beam characteristics of traditional phased array radar based on narrowband microwave phase shifter and optical phased array based optical true time delay line are discussed.The results show that using optical true time delay line can solve the problem of broadband Aperture Transition Problem of Radar.Then,we design and fabricate a tunable optical fiber delay line based on the binary differential structure of MEMS optical switch.The self-developed high-precision optical fiber grinding process can precisely control the fiber length within 0.06mm and realize 0.3ps time delay precision.Based on above technologies,the paper proposes a new 8×8 planar phased array transceiver system,and designs a phase-shifting network based on our self-innovate tunable optical fiber delay line.The feasibility of the scheme is being analyzed and simulated.The maximum value of the center angle of the scanning pointing error of the designed phased array system is 0.855°.In addition,in conjunction with the photonic RF channelization design in the receiver system,can reduce the demand for the high-speed broadband ADC on the back end of antenna.