Research On Transmitting Digital Beamforming Technology In Wideband Radar Jamming System

In the face of modern warfare,information warfare has become the mainstream war mode.By mastering the electromagnetic spectrum,you can master the initiative of the entire war.The nature of radar countermeasures is also the control of the electromagnetic spectrum.The trend of modern radar systems is digitalization and wideband.Therefore,the radar jamming system has followed the trend to fully realize digitalization and wideband.radar jamming systems need the ability to jam several enemy devices simultaneously,At the same time,we must avoid jamming with our own equipment.In this dissertion,research works on digital beamforming technology in wideband radar jamming system are carried out.First of all,this article introduces the existing radar jamming systems.Then,an radar jamming system based on time-varying weighted vector is introduced.In addition,digital beam forming(DBF)technology is an important part of radar jamming systems.Finally,the focus of this paper is on the digital beam forming technology that suitable for time-varying weighted vector jamming system.The main contents are as follows:1.The antenna array model,narrowband signal model and wideband signal model are studied.In addition,this paper introduces the basic principles of transmitting single beam forming and transmitting multiple beam forming.Finally,the existing jamming beam systems are studied,and the advantages and disadvantages of these jamming systems are analyzed.In addition,an radar jamming system using time-varying weighted vector that uses direct digital synthesizer(DDS)technology is introduced.2.First,this paper analyzes the problems existing in the application of traditional narrowband beamforming technology to wideband signals.Aiming at the time-varying weighted vector jamming system,delay-weighted beamforming algorithm,spatial resampling beamforming algorithm and linear constraint minimum variance(LCMV)adaptive digital beamforming algorithm suitable for the jamming system are studied.And wideband linear frequency modulation(LFM)signal is modulated with time-varying weighted vector to achieve wideband beamforming.At the same time,the method of transmitting multi-beam forming of the jamming system is given.Furthermore,the effects of the above-mentioned algorithm’s wideband beam forming and the simultaneous transmission of multiple beamforming are analyzed through simulation.Finally,the jamming system uses the LCMV adaptive digital beamforming algorithm,which has problems such as poor frequency invariance of different frequency components,the null broadening,and other problems.3.When the LCMV adaptive digital beam forming algorithm is used in the time-varying weighted vector jamming system,there will be a certain deviation in the beam forming of different frequency components in the broadband signal.At the same time,the beam pointing angle of the jamming system using this algorithm produces a certain degree of deviation.In response to the above problems,This paper introduces the definition of the spatial response variation(SRV)factor and the quadratic constraint LCMV criterion further optimized on the basis of the LCMV criterion.Then this paper proposes a new algorithm that combines the quadratic constraint LCMV criterion and the SRV factor.On this basis,the algorithm adds sidelobe constraint factors.What is more,the beam forming algorithm is transformed into a convex optimization problem,which effectively reduces the difficulty of the algorithm.