Study On ISAR Jamming Techniques Based On Scattering And Micro-motion Characteristics Modulation Of Targets

Inverse Synthetic Aperture Radar(ISAR) collects the scattering echoes of non-cooperation targets and coherently processes them to reconstruct a two-dimensional(2-D) high-resolution intensity image. ISAR plays an important role in many military applications such as imaging, classification, recognition, identification, guiding and destruction. The potentials of ISAR in such applications and the advanced ISAR systems in the world threaten the survival of military targets(such as satellites, aircrafts, naval vessels and missiles). The requirement for countering wideband ISAR imaging radars remains a high priority in electronic countermeasure(ECM) area. In order to protect the military targets via the ISAR retransmission active jamming, the jamming techniques against ISAR based on scattering and micro-motion characteristics modulation of targets are profoundly studied.The background and significance of ISAR jamming is introduced in this thesis. The developments of ISAR systems in the world and the present status of ISAR imaging techniques are also summarized. Furthermore, the problems in the ISAR active jamming are especially concerned. The major contents of this dissertation are addressed as followings:Firstly, the signal theory and methods of ISAR active retransmission jamming are addressed. The features of active jamming signals based on the intermittently sampling, sub-Nyquist sampling, and the pulse-divided retransmission after ISAR signal processing are analyzed. The difference and sameness between intermittently sampling and sub-Nyquist sampling are discussed in this chapter. The conclusions are also validated by the simulation results. A novel retransmission jamming is presented based on pulse-divided against LFM radars. Formulas of divided number on condition that false targets hold amplitude dominance and retransmitted order with the maximum number of false targets are presented.Secondly, based on the active retransmission jamming and scattering characteristics modulation in ISAR jamming application, the scatter wave jamming method is adopted in ISAR deceptive image jamming. The features of the deceptive images in ISAR imaging plane are discussed and the various jamming effects with different intermittent sampling intervals, duty ratios and the equivalent bistatic angle are also addressed. A new jamming approach of applying pulse divided and retransmission against the LFM-ISAR is also presented. Based on the divided number and the retransmitted order, the number and the resolution of deceptive images are described. False-target images are of great potential for countermining ISAR, but suffer from insufficiency on a moving platform. The signal modeling and imaging of the false target of non-cooperative moving platform in the Self-screening jamming(SSJ) scenarios are concerned. The influence of the modulation coordinate, coordinate offset and angular velocity on the jamming performance is also analyzed. The results demonstrate that a false-target image would be induced in the image plane via phase and amplitude modulation of the phase samples.Finally, the imaging features of the rotating targets are revealed and the modulation jamming methods based on rotating micro-motion are also proposed. Firstly, the echoes of rotating targets in the stepped-frequency ISAR is modeled and processed. The results in the imaging plane of ISAR are verified by the outfield experiments. Based on the imaging characteristics of the rotating targets and sub-Nyquist sampling, the research of micro-motion modulation ISAR jamming method is analyzed. Micro-motion modulations jamming not only contaminates the readability of ISAR images, but also can be utilized to deceive the identification of radar. The micro-motion characteristics modulation jamming based on sub-Nyquist sampling can contaminate the ISAR image in both the down-range and the cross-range since sub-Nyquist sampling spreads the micro-motion modulation effect into various range cells.The development of ISAR systems are vigorous and many new ISAR imaging techniques are also proposed and adopted in real applications to deal with more complex moving targets. The main work in this dissertation not only consummates the ECM systems and enriches the jamming methods of ISAR, but also assists the ISAR jamming implementation. The conclusions of this paper can also be developed to provide guidance in ISAR deception jamming, micro-mition modulation jamming, and etc.