基于方位向多波束-多相位中心的星载SAR多维波形编码技术研究

Study of Space Borne SAR Multidimensional Waveform Encoding Technology Based on Azimuth Multi-Beams Multi-Phase Centers

通过方位向多波束与多相位中心结合,采用方位向-快时间二维波形编码发射技术获得了星载SAR系统高分辨-宽测绘带成像的优良性能.所提方案在发射端的方位向采用脉内扫描形成多个方位窄波束,以减小子多普勒带宽,距离向通过波束展宽获得宽测绘带;在接收端沿距离-方位向形成多个等效相位中心,通过俯仰DBF技术分离各子波束回波信号来抑制距离模糊,方位向通过谱重构方法解方位多普勒模糊,并通过多个子多普勒谱拼接获得方位高分辨.文中研究了本系统的主要系统参数典型设计及性能优势.仿真结果表明,该系统能有效的完成高分辨-宽测绘带任务,相对已有的其它星载SAR系统,系统性能优势明显,系统结构更加轻便灵活.

This paper introduces a new waveform encoding technology on azimuth-fast time domain for space borne synthetic aperture radar （SAR）,this technology can obtain high resolution wide swath imaging capacity by combining the azimuth multiple beams with multiple phase centers. On the transmitter, inVapulse scanning technolog is utilized to form multiple narrow beams on az- imuth in this system, which can reduce the sub-doppler bandwidth,and the elevation beam is widened for wide imaging swath. On the receiver,multiple equivalent phase centers are produced both on azimuth and elevation, the range ambiguity is deducted as the result of multiple sub-waveforms separated by digital beam-forming （DBF） on elevation,and the azimuth doppler ambiguity is de- ducted by doppler spectral reconstruction method. Finally, the multiple sub-doppler spectra are combined to achieve high azimuth resolution.Moreover, the primary system parameters and performance advantage are analyzed. Simulation results confirm this new system can fulfill high resolution wide swath imaging,also within condensed configuration than other space borne SAR system.