Study On Countermeasure Performance Of Adaptive Side-lobe Cancellation System

Today, radar is facing complex electronic jamming environment. The radar which has anti-interference ability will have vitality. Most electronic jammings enter receiver from radar antenna side-lobe, the most effective anti-interference technique is antenna side-lobe cancellation. This thesis studies coutermeasure performance about adaptive side-lobe cancellation. Main content of the thesis is described in the followings:The principle of adaptive side-lobe cancellation and calculation methods of weights are studied in this thesis. The simulation of system's performance about the number of samples and the ratio of signal-jamming shows that the bigger the ratio of signal-jamming, the greater the cancellation during calculation of number of samples. It analyses some valuable problems when ASLC is applied in project application, including the number of auxiliary antennas, noise of channel, frequency band and wave path difference, etc. Corresponding performance curve is gotten.The performance of adaptive side-lobe cancellation system is studied on narrowband interference condition. The cancellation performance of system is reduced as the modulus of signal correlation coefficient increases. The coherent jamming has an advantage over non-coherent jamming for side-lobe cancellation. The better interference correlation, the worse system performance degradation. The anti-jamming effects about synchronous delay interference are studied in the third chapter.The performance of adaptive side-lobe cancellation system is studied on broadband interference condition. Through analysis of relationship between destructively gain and interference bandwidth, we can see that the increase of relative bandwidth will make destructively gain become smaller. Using broadband interfering signal mathematical model, we can find that broadband noise FM disturbance can countermeasure anti-interference measures. In order to solve the problem of system performance's deterioration, we analyses three improvement measures in the fourth chapter.Finally this thesis simulates pattern of antenna. This thesis discusses generalized side-lobe cancellation and construction of blocking matrix, because that the side-lobe systems would go worse with the existence of desired signal and mainlobe jamming inside sampling signals. It proves that the simulation of pattern of antenna based on generalized side-lobe cancellation could increase the cancellation performance.