Research On Passive Jamming Method Based On Absorber Materials

With the rapid development of modern electronic technology,electronic warfare has become one of the key factors in the victory of the future war.Due to the continuous improvement of radar technology,radar jamming technology,which is the key to destroy the enemy’s weapons and equipment and protect the effectiveness of our own weapons,is facing severe challenges.Therefore,it is of great significance to develop an effective radar jamming technology.Compared with active jamming,passive jamming method has the advantages of low price,wide frequency working band,direction,polarization,and has the ability that working with all kinds of threat signals at the same time in complex electromagnetic environment.The effects of traditional passive jamming technology are subject to many factors.The emergence of the stealth technology can solve the problems which the traditional passive jamming method facing.The essence of the stealth technology is to realize the significant decrease of the radar echo energy,which has a fundamentally different with traditional passive jamming method.By optimizing the detected target shape or coating on the surface of detected target,the features of the detected target can be hidden.The radar absorbing materials(RAM)is a key factor in stealth technology,which makes it possible for the protection of high speed flying target using the passive jamming method.It can be used for the high speed flying target to stealth,and the jamming effect has been fully verified in many wars.Restricted by the weight,the thickness and the effective bandwidth of the traditional RAM,the effectiveness of the traditional RAM used for target stealth is very limited.Two kinds of special radar absorbing material are selected in this dissertation which can realize the complex modulation of radar electromagnetic wave in addition to the strong absorption ability.Based on the resonant absorption effect of electromagnetic metamaterials and plasma,a new passive jamming method is proposed.It is found that electromagnetic metamaterials and plasma both can achieve double interference effects:one is having the strong absorption effect on radar echo,and the other one is realizing the false target jamming effect due to the radar echo waveform distortion.The main innovation and contribution of this dissertation can be summarized as follows:1.The electromagnetic metamaterials and plasma are selected in order to realize the jamming effect because of the complex modulation to radar electromagnetic wave.Using the electromagnetic calculation method,the electromagnetic characteristics of the radar signal echo are obtained,when the plate targets coating with electromagnetic metamaterials and plasma respectively.In addition to this,the radar echo signal model is established.Based on the resonance absorption,the mechanism of the novel jamming method using electromagnetic metamaterials and plasma is studied.By taking the pulse compression radar an example,the jamming effect on the radar echo waveforms of three kinds of typical radar signals including linear frequency modulation(LFM)signal and nonlinear frequency modulation(NLFM)signal and the linear frequency modulation and binary phase shift keying(LFM/BPSK)signal under the action of EM MMs and plasma respectively.The study results show that both the two kinds of the special radar absorbing materials can make the pulse compression radar signals distort,mainly displaying in two aspects:the strong attenuation of the radar echo signal and the change of the radar echo’s the amplitude modulation and phase modulation.2.Based on the three typical pulse compression radar signals distortion mentioned above,the jamming effect on radar signal detection is studied.Through making comparisons of pulse compressing results with and without the two special RAM,it is found that the outputs of pulse compressing are different under the different parameter conditions.When the appropriate RAM parameters are chosen,the pulse compression peak is attenuated by several dB or even tens dB,meanwhile,ranging errors of several decimeters are found in both simulation results.Moreover,besides the great attenuations,single radar target becomes two false targets with several meters apart after the pulse compressing process.This is an excellent jamming effect on the radar detection.By adopting the detection probability Pd≤0.1 as a valid jamming criterion,the effective RAM parameters for different radar frequencies are given.These parameters provide references for the designing of jamming technology applied to aircrafts and missiles for practical engineering application.3.Considering the advantage of EM MMs which is easy to conformal with radar targets,a novel jamming method using electromagnetic metamaterials to realize passive jamming to Inverse Synthetic Aperture Radar(ISAR)is proposed in this dissertation.Taking the cross-shaped metamaterial structure design as an example,the jamming effect on ISAR imaging result of X band radar is studied.Firstly,the jamming effect on the radar one-dimensional range profile is verified based on the point scattering model.Besides the half of the energy attenuation,signal radar target becomes two radar false targets with several centimeters apart.Based on the research above,cross-shaped metamaterial is used to jam the ISAR imaging of the missile target.The ISAR imaging model of the target coated with cross-shaped metamaterial is established and the imaging mechanism is studied.Finally,the simulation results indicate that cross-shaped metamaterials has an excellent jamming effect on the ISAR imaging result.Based on the resonant absorption effect of metamaterials and plasma,a novel passive jamming technology is proposed in this dissertation.It is found that electromagnetic metamaterials and plasma can make the radar echo distort,which leading to the attenuation of the pulse compression peak value and the false targets with several meters apart from the real target.In addition,it can also be used to jam the ISAR imaging result.The passive jamming technology not only can solve the restrictions of traditional passive jamming method for flight target protection,but also have the advantages in engineering and applications,proving a new concept for the passive jamming technology.