基于直接数字频率合成器的新型微波成像系统

Novel microwave imaging system based on direct digital synthesizer

研究并实现了一种Ku频段的相控阵被动微波成像系统.该系统使用直接数字频率合成器(Direct Digital Synthesizer,DDS)进行上变频后作为射频通道的本振信号,通过DDS作为等效移相单元来实现相控阵成像系统的移相.对比传统使用数字移相器方案,该成像方案可以对视场内的景物进行几乎连续的高密度电扫描,具有扫描时间短、移相精度高、扫描像素高等优点.系统的实测成像结果表明:基于DDS的相控阵微波成像方案具有成像质量高、成像速度快、系统成本较低等优势,是一种有着良好研究前景的新型微波与毫米波成像技术.

A novel phased array passive microwave imaging system based on direct digital synthesizer(DDS)technology is proposed and implemented,which uses DDS to indicate the local oscillator signal for the RF channel after its up-conversion with a fixedfrequency local oscillator.DDS is used as the equivalent phase shifter for the phased array imaging system due to its high phase resolution and fast phase shifting capability.Compared to the traditional phased array imaging schemes which use the digital phase shifters,the proposed imaging scheme has the capability to make almost continuous high density scanning for the field of view with the advantages of high scanning speed,high resolution of phase shifting and high scanning pixels.The measured imaging results show that the imaging schemes based on DDS have the advantages of better imaging quality,high imaging speed and lower cost,which demonstrates that it is a promising technology for microwave and millimeter wave imaging.