数字相控阵天线中的波束合成实现方法

摘要

数字相控阵天线是有源相控阵天线发展的重要方向,而信号处理的核心内容是波束合成.但波束合成的工程设计中面临的一些问题,往往通过经验进行处理,并未从理论角度进行分析和解决.首先,针对信号处理硬件平台中的数据采集功能,通过分析ADC噪声来源,并结合输入中频信号SNR、动态、采样处理增益,得到了满足输出SNR要求的最少有效比特位的解析表达.其次,根据数字相控阵阵因子表达,分析了在指向误差对方向图影响,根据天线增益的损失,可以确定指向误差的允许范围.另外,根据空间色散原理,分析了频偏对阵列方向图影响,同样根据天线增益损失,可以确定允许的信号带宽指标.上述指标确定方法,通过计算机仿真证明了正确性和有效性,从而为数字相控阵天线的工程实现,提供了有益的支持.%Digital phased array antenna is an important trend for the development of active phased array.And beamforming is the key content of the technology.There are some issues faced during the implement by engineers,which are not well solved through the fundamental theory.Firstly,through investigating the source of ADC noise,SNR and dynamic range of input intermediate frequency signal,and the processing gain in sampling as well,the way to determine the least ENOB in the data sampling was obtained for signal processing hardware platform.Secondly,the allowable error of directional angle was analyzed according to the array factor formulation.Since the error can cause the distortion of pattern for phased array,and the pattern decides the array factor and antenna gain,the allowable error can be induced by the allowable gain reduction.In addition,the relationship between the signal bandwidth and antenna gain is created.Based on the theory of spatial dispersion,the frequency shift,which is caused by the signal bandwidth,can attenuate the gain.The ENOB,error of directional angle and signal bandwidth mentioned above are all dominant parameters.So the proposed conclusions for the selection of these parameters are constructive greatly to the implement of digital phased array.Some computer simulation also proves that these approach are correct and effective.