基于调频Z变换的均匀线列阵恒定束宽波束形成器设计

Design of a constant beamwidth beam-former for uniform linear array based on Chirped Z transform

提出了基于调频Z变换(CZT)的宽带恒定束宽波束形成(CBB)方法:假设在每个子带内,各方位波束的权系数相同,推导得到:每个频率子带的权系数序列与参考频率的权系数序列的频谱相同,而在频率轴上满足比例伸缩关系,比例尺度为参考频率与相应频率子带的中心频率之比。依据此设计思想,给出有效孔径不变的CZT法(CZTIA)和有效孔径变化的CZT法(CZTVA)两种CBB实现方法。它们均是由参考频率的权系数序列,通过设定不同的参数值,采用CZT快速计算各个子带的权系数序列的频谱,然后通过傅里叶反变换便可得到相应频率子带的权系数序列。计算机仿真结果验证了理论分析的正确性。

Design of a constant beamwidth beam-former（CBB） based on Chirped Z Transform（CZT） are proposed： within every frequency sub-band,assuming that weighting coefficient sequences of beams oriented to different directions are the same.Then it can be concluded from the deduction that the sequences in all sub-bands have the same spectrum, but a scale relationship is satisfied on the frequency axes.The scale is equal to the ratio of the reference frequency to the central frequency in each sub-band.According to the design ideas of CBB,the CBB method based on CZT with Invariable Aperture（CZTIA） and the one with Variable Aperture（CZTVA） are presented.It is the same in these two methods that the weighting sequence of the reference frequency is obtained firstly,and then by use of CZT with different parameters values,the spectrums of weighting sequences in all sub-bands can be calculated,and finally they can be obtained by inverse fast Fourier transform（IFFT）.The validity of these conclusions is validated with computer simulations.