Research On Key Technologies Of Hf Frequency Diversity MIMO Radar Beamforming

Beam controlling is an important research in the field of radar.Phased array digital beamforming technology refers to the introduction of digital processing methods based on traditional phased array radar for beamforming.It aims at forming desired high-quality beams by change the weight of the transmitted or received signals in the digital field.It can flexibly control the transmitted and recivied beams,and the beam forming accuracy is high and the adaptability is strong,which effectively overcomes the shortcomings in the analog phased array radar.There are many application scenarios that require higher dimensional requirements for radar beam controlling,so scientists try to apply the frequency diversity MIMO system to the beam forming technology of high-frequency radar,combined with the two-dimensional area array structure to form more accurate in stereo space Beam.The thesis first analyzes the basic principles of phased array,simulates the pattern of uniform linear array and rectangular area array antenna,and studies the influence of different system parameters such as the number of elements and the distance between elements on the antenna pattern.At the same time,the anti-jamming performance of the adaptive beamforming in the pitch direction of the area array is studied,and the interference of the reflected ionosphere in the zenith direction is suppressed.In many cases,a single beam cannot meet the application requirements,so digital beamforming technology can be used to form multiple beams with different directions at the transmitting end,and the waveform of the signal can be individually controlled.Multibeamforming technology can also be used at the receiving end to observe simultaneously Airspace with multiple orientations.Aiming at the problem of transmit beamforming of frequency diversity MIMO radar,a transmit array model of frequency-controlled array is established according to different array structures,and the beamforming principle of multi-carrier frequency linear array and multi-carrier frequency area array and the space of beam pattern are deeply studied.Distribution characteristics.Frequency diversity MIMO radar can be regarded as a generalized array of phased array radar,focusing on comparing and studying the difference between the two patterns and the effect of different system parameters on the beam pattern of the multi-carrier frequency array.In order to eliminate the coupling characteristics of the frequency-controlled array radar emission pattern,an effective optimized beamforming method is proposed,which forms a high-gain spot beam in space,which is more conducive to the beam scanning at different angles and target positioning in space.The principle of multi-carrier frequency signal generation based on digital T/R component technology is also studied.Aiming at the problem of freedom of transmission and reception of frequency diversity MIMO radar,research on characteristics and resolution technology was carried out.MIMO radar has more degrees of freedom in adaptive beamforming to suppress interference.Frequency diversity MIMO radar transmits orthogonal multi-carrier frequency signals at the transmitting end to cover the entire target airspace.The receiving end uses multiple antenna array elements to receive the target reflected echoes and then performs matched filtering on the received signals to achieve signal separation and extraction.Due to the use of frequency diversity system,a virtual array element can be formed at the receiving end to expand the array aperture and improve the resolution and target detection performance of the radar.