Novel Antenna Array Synthesis Methods And Adaptive Sidelobe Cancellation Algorithms

In radar or electronic warfare systems, the interference signal enter into the systems generally from the sidelobe because the main beam is narrow.Under normal circumstances, the sidelobe gain is much lower than the main lobe gain. But the power of active interference signal come from sidelobe will be far greater than the power of target signal come from main lobe when the interference is strong. We can’t separate the target signal from the interference signal,thus the system can’t work effectively. For such a strong interference from sidelobe,we have three methods to handle it. It contains ultra-low sidelobe technology,sidelobe blanking technology and sidelobe cancellation technology.The realization of the ultra-low sidelobe technology depends on innovation of antenna array synthesis method. The radiation characteristics of antenna array is decided by the number,position and weights of elements. The three factors can change the radiation characteristics of antenna array. Synthesis of antenna arrays means optimizing the number,position and weights of antenna array to get array pattern satisfying given conditions. The first part of this paper introduce the basic theory and methods of antenna array synthesis. It contains matrix pencil method and matching pursuit method.Ultra-low sidelobe technology can improve the ability against sidelobe interference. But its realization is difficult and costly, even with regard to the large loss of resolution. If we use the sidelobe blanking technology, the target signal will be masked when the interference signal exist. Thus we generally use the sidelobe cancellation technology in practice. It can form desirable nulling in the direction of interference when using a few auxiliary antennas. This method has strong anti-interference ability without changing the gain and beamwidth of the main lobe. The second part of this paper introduce the basic theory and method of sidelobe cancellation. This paper introduce an adaptive-adaptive sidelobe cancellation to improve the SNR and the ability of keeping the shape of sidelobe. First of all, we estimate the interference direction. Then we form beam in the direction of interference by using beam forming technology. At last, we use the sidelobe cancellation technology. It is observed that the new method can improve the SNR by simulation.