Design And Development Of Broadband Array Antenna Digital Beamforming System

Digital array antennas using digital beamforming technology can simultaneously form multiple digital beams with independent control of beam pattern characteristics,and have the capabilities of space domain adaptive interference suppression and high-precision angle estimation,etc.So it has been widely used.Existing digital beamforming systems are mainly narrowband systems.With the requirements of radar range resolution improvement in practical applications,the related signal bandwidth should be increased.The wideband digital beamforming system is the trend of digital array radar in the future.In order to develop a 48-channel sub-array wideband digital array radar system,a softwarebased wideband digital array radar processing system architecture based on high-speed switching network in accordance with VITA46 standard and 6U VPX structure is proposed in this paper.Modularity,standardization and scalability are fully considered in this system.The system architecture and its implementation of the wideband sampling digital beamforming subsystem are designed and illustrated in detail.The subsystem can achieve high-speed data sampling of the wideband signal with 250 MHz and the narrowband signal with 30 MHz,software defined radio preprocessing and simultaneous 16 digital beams forming.All the functional and performance testing of the digital array antenna can be accomplished under the control of the host computer.The integration with radar signal processing modules is underway.The main work of this article includes:1)Aiming at the actual requiement of the subarray wideband digital array radar,a modular,standardized,and scalable system platform and interconnection scheme based on highspeed switching network is proposed.The function assignment of each board module of the system and its high-speed interconnection topology are analyzed in detail;2)The hardware circuit design of the 24-channel wideband IF sampling and pre-processing board module have been completed,including: the hardware circuit implementation scheme and the schematic diagram design;3)The circuit welding,software design,debugging and testing of the wideband IF sampling and pre-processing board module have been completed.The FPGA software includes multi-channel analog-to-digital conversion high-speed JESD204 B interface,software radio processing,digital multi-beam forming and high-speed data transmission software module and other functional modules.All of them are completely debugged and verified;4)The testing of the main functions and partial performance of the subsystem,consisting of the wideband IF sampling and preprocessing board module and the adaptive beamforming board module,is completed.The effective number of bit(ENOB)of ADCs and the channel frequency response characteristics are tested.The system functions such as channel selftest and calibration,baseband data acquisition and the digital beamforming are also verified.