Low Sidelobe Digital Beam Forming Algorithm Research

Adaptive array technique is one of the branches in array signal processing. It has played an important role in both military and commercial application fields, such as radar, communication, sonar, navigation, acoustics and speech signal processing, and so on. During the system property parameters, low sidelobe is always a popular topic. Under more and more complex electromagnetism environment, low sidelobe has become very important role in electronic warfare reconnaissance domain. Based on the low sidelobe, the contributions of the dissertation can be summarized as follows:1. The array signal model was introuduced and the conventional bemforming algorithms were studied.2. Based on the LCMV beamforming algorithm, the diagonal loading algorithm and general linear combination covariance matrix modifying algorithm were studied.These two algorithms can make the outputting beampattern have better performance and lower sidelobe. Changed the diagonal loading value, the changing rules of the sidelobe and mainlobe breadth were analysed. And based on the changing frequency and changing inputting SNR, the sidelobe performance is studied.At the same time, a new algorithm which can give the range of the diagonal loading value and the simulation also was made. And the robust digital beamforming algorithm whcich is based on W-RABF was studied.3. The subarray level digital beamforming algorithm was systematicly analysed. It can reduce the complexity and cost of the system, the simulation results for the line array and planar array were given.4. A low sidelobe algorithm was proposed which can update the optimal weights through searching and restraining. Every time for searching to achieve the position of the highest sidelobe, then added restraint to the position to have new weights. Based on the line and planar array, the algorithm is verifying. The amplitude weighting algorithm be studied and a new algorithm for the ununiform toroid array is proposed, the simulation which had a good performance is made.5. The algorithms for the array calibration were studied and analysed.Based on the correlation algorithm and Least Square algorithm, the calibration results for the seven arm circle ring array were achieved.