通道失配对超视距雷达DBF副瓣电平的影响

The frequency response mismatch between the channels and its effects on the sidelobe level of OTH radar

在超视距雷达中 ,需要经过 FFT来获得距离信息。FFT对于正弦信号而言是匹配滤波器 ,随着积累时间的增加匹配滤波器的带宽会随之减少。不同距离单元的幅相不一致性与不同的频率相对应。随着 FFT点数的增加 ,每个距离门对应的带宽会不断减小 ,带内的起伏会随之减小。同一距离门之间的幅相误差趋于固定 ,经过校正后 ,DBF的性能也会有提高 。

In OTH radars, the range information is obtained by FFT. The FFT is a match filter for sinusoid signal, and the band width of the match filter will decrease with increase in integrated time . In a particular range gate , the inconsistancy of amplitude and phase between the channels is corresponding to that of a particular band. As the band of the filter decreases, the viariation of amplitude and phase inconsistancy in the band will decrease too. The inconsistancy between the channels tends to a fixed value. After calibration, the performance of the DBF will be improved. The requirement of OTH radar for the amplitude and phase consistancy between channels will be relaxed.