通道失配对超视距雷达DBF副瓣电平的影响

在超视距雷达中，需要经过FFT来获得距离信息。FFT对于正弦信号而言中匹配滤波器，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，超视距雷达对接收通道频响一致性的要求将有所放松。

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

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.