中文摘要：

在低频超宽带合成孔径雷达中,VHF/UHF频段密集的窄带射频干扰（RFI）严重影响了雷达性能。常规RFI抑制滤波器在干扰频点的陷波造成了宽带信号的能量损失,抬高了点目标的距离向旁瓣。该文提出一种可减小自适应滤波器旁瓣效应的方法：通过在距离压缩域剔除场景内的强散射点,减小输入信号中的宽带目标信号能量,提高自适应谱线增强器（ALE）对窄带干扰估计的精度,再从原始信号中减去干扰即得到目标回波信号。这种剔除强散射点的方法利用了匹配滤波后宽带信号与窄带干扰的时域特性差异,能有效降低自适应滤波器的旁瓣效应。该文选择归一化最小均方误差（NLMS）算法对剔除强散射点的自适应窄带RFI抑制滤波器进行了性能评估,与传统算法的对比试验表明该方法可在抑制RFI的同时有效减小强目标的距离向旁瓣。

英文摘要：

The performance of low frequency Ultra-Wide-Band（UWB） Synthetic Aperture Radar（SAR） is seriously affected by narrow band Radio Frequency Interference（RFI） in the VHF/UHF band. RFI suppression, by placing notches over the energy spectra to remove the RFI spikes, results energy loss of the wide-band signals and raises the range direction side-lobes. This paper presents an approach to suppress the side-lobe in range direction caused by adaptive filtering. After clipping main energy of strong scatterers in range compression domain before RFI estimation, the interference signals are estimated using an Adaptive Line Enhancer（ALE） and subtracted from the radar echo. The clipping approach makes use of the different time-domain characteristics between wide-band signal and narrow band interference, and by using pulse compression technology the method can be processed efficiently. To investigate the performance of RFI suppression, clipping of strong scatterers is combined to the ALE based on Normalized Least Mean Square（NLMS） algorithm. Simulation results and experimental data test compared with the conventional algorithms suggest that side-lobes of the strong scatters can be reduced effectively in RFI suppression.