Adaptive Interference Nulling And Beamforming Algorithm

The modern digital array radar system generally apply adaptive algorithm to control the nulls position of the beamforming and to suppress interferential signals. It is one of advanced technologies used in modern radar.Phase-only beamforming algorithm mostly used in control the beam nulling. Phase-only algorithm only uses the phase information of the weights so it is easy to actualize. In order to make full use of the abilities of transmitting function modules, phase-only method is an optimal solution for radiation nulling. However, this method only uses information of weights so that equations for defining phase perturbations are generally unlinear. Therefore, the analytical solution is more difficult. At present some familiar algorithms are small phase perturbation restriction algorithm, big phase perturbation restriction algorithm, maximum gain of the expected direction restriction algorithm and so on.The tactics performance improves of array radar mostly hanging on the ability of multiple beamforming. When we used radar to observe multi-target, the array antenna may form multiple beams, aim at different targets. In special time, it even can cover with all the airspace. There are many methods to form multiple beams, this dissertation also introduced the digital multiple beamforming based on FFT.To solute the difficult unlinear equations, the dissertation introduced small phase perturbation restriction algorithm in Chap.3, deduced the principle of this algorithm and did the simulation experiment, then introduced maximum gain of the expected direction restriction algorithm in Chap.4, deduced the principle of this algorithm and did the simulation experiment too. This paper goes into details on two practical phase-only algorithms including their theories, simulation results, and performance analyses. Both the two algorithms can be applied to adaptive arrays working on radiation mode, thus greatly improving radar anti-jamming capabilities.Before used phase-only algorithm to do beam nulling, we must know principle of adaptive beamforming and multiple beamforming. So this paper introduced these two principle and deduced the principle of this algorithm and did the simulation experiment. The Chap.5 is the most important chapter of this dissertation, it mainly introduce the instance of applying maximum gain of the expected direction restriction algorithm to do the beam nulling in Wideband Digital Array Radar (DAR).Therefor this chapter introduced three technology of wideband beamforming and deduced the principle of this algorithm and did the simulation experiment, educed result of experiment. Otherwise this chapter simply introduced multiple beam nulling and made the primary discuss. Lastly, I made a conclusion in Chap.6.