Wideband Digital Beamforming Algorithm Research

Modern Radar usually works in the environment which is full of electronic interferences coming from different directions. It is difficult to suppress these interferences while only depending on the information of time and frequency domain. While the digital beam forming (DBF) technique can suppress interferences via its capability of adaptive low side-lobe and adaptive nulling. However, for the modern radar, especially the high-range resolution (HRR) radar and large-scale array antenna radar, the conventional DBF technique is difficult to obtain good result of interference suppression. Therefore, it is necessary to developing new DBF algorithms for modern HRR radar and large-scale array antenna radar.For the HRR radar, aiming at the problem of wide-band and channel unequalization, we proposed a novel DBF algorithm which is based on the channel equalization. For the large-scale digital array antenna, aiming at the problem of many hardware devices and complicated system of the conventional DBF algorithm, we proposed a novel DBF algorithm which is based on the technique of several subarrays.This paper firstly introduces the basic conceptions and recent researches of the wide-band digital beam forming. And then discusses the static polar diagram, the side-lobe, the grid-lobe, and the beam width of the array antenna and planar array. The paper also studies adaptive signal model, and makes theory analysis and comparison of the basic standards and algorithms.The paper introduces both the narrow-band signal model and wide-band signal model, and analyzes the influences of channel mismatching. And then the paper discusses the algorithms and realizations of both the time field channel equalization and the frequency field channel equalization, and gives simulation results of the channel equalization.In the last, the paper studies sub-array dividing technology and some adaptive beam forming algorithms of the digital antenna array. The paper discusses frequency field processing method in allusion to the dispersive problem. In this method, we make the received signals do the DFT transformation, and make the sub-frequency band decompose, and then adopts the incoherence signal method (ISM) or coherence signal method (CSM) to make beam forming. In the coherence signal method, we discuss the RSS algorithm, the LS algorithm and the coherence focusing algorithm, and give the corresponding simulation results.