Array Design Of MIMO Radar Anti-active Jamming

MIMO means multi-input and multi-output.This technology is first applied to wireless communication,and researchers are concerned because of its good diversity characteristics.Subsequently,radar-related researchers applied MIMO technology to radar and proposed a new concept of MIMO radar.Compared with early phased array radars,MIMO radars have high degree of freedom,good target recognition capability,and parameter estimation performance.Therefore,MIMO radars have become a key research direction for radar-related researchers.At the present stage,the MIMO radar system types mainly include distributed MIMO radar and collocated MIMO radar.Each array element spacing of distributed MIMO radar is larger,and each of the emitting elements emits waveforms of different symbol,frequency,or polarization characteristics.Therefore,the probability that the transmitting and receiving elements of the MIMO radar are interfered at the same time is relatively low.The transmitter collocated MIMO radar forms wide beam(or omnidirectional beam)in space.By processing multiple beams at the receiver,the interception's probability of the target signal is reduced to some extent.With the development of electronic jamming technology,the high sensitivity of modern electronic reconnaissance receiving equipment shows that MIMO radar still faces a huge risk of being disturbed.This thesis mainly discusses that in the active interference environment of the collocated MIMO radar,the main lobe of the synthesized beam pattern points to the target directions,and generates nulls in the active interference directions to realize the suppression of active interference.Since the synthesized beam pattern of the MIMO radar is related to the array configuration,this thesis focuses on improving the anti-active interference performance of the MIMO radar by using the MIMO radar array design.The main contents are as follows:First of all,because the essence of MIMO radar is based on the principle of array,the basic principle of array signal is introduced firstly.Based on this,the basic concepts and basic principles of MIMO radar are introduced,and the principle of virtual array element formation of MIMO radar is analyzed,and the MIMO radar pattern formula is derived.Then,the signal model of MIMO radar in active interference environment is established,and the beamforming algorithm of MIMO radar in active interference scenario is analyzed.Secondly,it is proposed that an anti-active interference method based on new sparse array(nested array and coprime array)MIMO radar array design.Early traditional MIMO radars use uniform linear array as the transceiver array.The number of anti-jamming is mainly limited by the number of virtual array elements(the product of the number of transceiver elements).The new sparse array is used as the receive array of MIMO radar and passes through Khatri-Rao product preprocessing can greatly expand the aperture of the MIMO radar's virtual array and improve the system's freedom.Therefore,it is possible to suppress the number of active interferences more than the product of the transceiving elements.Through simulation experiments,it can be proved that the MIMO radar based on the new sparse array can suppress the number of active interferences more than the product of the transceiving elements.At the same time,the new sparse array MIMO radar reduces the number of physical elements and reduces the complexity and cost of the system while improving the freedom of the system.Finally,an anti-active interference method for MIMO radar based on array elements positions control is proposed.The MIMO radar anti-active interference method based on array elements phases control and array elements positions control are introduced.The main idea of these two methods is to point the main lobe of the MIMO radar synthesized pattern to the target directions through the perturbation of the elements phases(or the perturbation of the positions of the elements),and to make nulls in the directions of the active interference to realize the suppression of active interferences.In the end,it is proposed that an anti-active interference method for MIMO radar combined with elements phases control and positions control.This method can make the MIMO radar synthesized beam pattern form deeper nulls in the active interference directions,and the effect of suppressing active interference is better.