Research On Wideband Imaging Technology Based On Microwave Photon Radar

Inverse Synthetic Aperture Radar(ISAR)can acquire imaging of target under the condition of all day and all weather,even in the night or bad weather,which can’t be achieved by optical systems.Therefore,it is widely used in military and civilian fields.With the increasing demand for high resolution of radar,in order to obtain high quality ISAR images,not only the enhancement of radar hardware but also the improvement of imaging algorithms are required.Therefore,the wideband radar based on microwave photon technology and its imaging technology are studied in this paper.The research contents of this paper include:1.In this paper,the basic working principle and structure of microwave photonic system are studied.On this basis,an ultra-wideband imaging radar system based on microwave photonic technology is designed and an experimental prototype is constructed.In the transmitter part,the linear FM signal with 2GHz bandwidth is multiplied from X-band to Ka-band,and then the frequency conversion to Ku-band is completed by the three-stage Mach-Zehnder modulator under an all-optical frequency conversion network to realize 12-18GHz ultra-broadband linear FM signal.In the receiver part,the receiver echo is modulated directly to the spectrum by using the swept spectrum sideband generated by the transmitter,so as to realize the all-optical de-skew receiving processing.The radar experimental prototype achieves 6GHz instantaneous bandwidth in Ku-band(12-18GHz),with tunable and scalable bandwidth and center frequency,and a relative bandwidth of 40%.2.Based on the above built microwave photon radar imaging experimental system,the amplitude-phase compensation algorithm for large bandwidth signal is studied under the condition that the amplitude-phase in the system band is not ideal,and the resolution and peak side flap ratio of the one-dimensional distance image of the ideal point target after compensation are basically consistent with the theoretical value.On this basis,the wideband imaging technology based on time-domain sampling transformation is proposed to solve the problems of image defocus and blur in the process of wideband imaging,and improve the imaging quality of the target.