阵列冲激雷达关键技术研究

发布时间：2018-01-14 15:02

本文关键词：阵列冲激雷达关键技术研究　出处：《电子科技大学》2017年博士论文　论文类型：学位论文

【摘要】：冲激雷达是一种新兴的超宽带雷达技术,通过发射无载波冲激脉冲对目标进行探测或识别。由于冲激信号的脉冲宽度窄,频谱分量丰富,冲激雷达和连续波雷达相比有巨大的应用潜力,在距离分辨率、角分辨率、反隐身、穿透能力等方面都优于窄带的连续波雷达。本文关于阵列冲激雷达的技术研究,首先是对冲激电脉冲信号源的研究,电脉冲源不仅要求输出功率高,同时要求触发抖动低,易于实现阵列的同步输出;另外对阵列辐射冲激电磁脉冲的传输特性进行研究,根据其能量传输、叠加的基本规律,分析阵列冲激雷达高分辨率的原因;最后对冲激信号作用下目标散射的物理图像进行研究,期望对冲激雷达目标探测提供一定的理论基础。针对冲激电脉冲源高峰值功率低触发抖动的需求,本文选用半绝缘GaAs光导开关作为电脉冲源,采用理论和实验相结合的方法对半绝缘GaAs光导开关进行研究。首先对GaAs材料的光吸收机理进行分析,通过计算发现半绝缘GaAs光导开关对1064 nm的光吸收主要是由于EL2能级的光致电离吸收。接下来对光导开关进行暗态测试时发现,暗电阻随电场变化并非单调减小,在某段电场范围内甚至会随电场增加而增加;结合载流子的热电子效应以及杂质的碰撞电离效应对暗电阻的变化规律进行分析。其次,在1064 nm激光脉冲激励下,分别对半绝缘GaAs光导开关的线性模式和lock-on模式进行了实验测试。线性模式下开关的亚线性伏安特性和输出电压饱和特性表明,线性光导开关的最佳工作光能为输出电压开始饱和时对应的光能;通过与开关的暗态伏安特性进行对比发现,当电场大于3 kV/cm时开态电竟然随电场增加继续增加,从根本上说明了线性光导开关无法实现高增益的原因。另外,对半绝缘GaAs光导开关锁定(lock-on)模式阈值条件进行实验测试时发现,开关进入lock-on工作模式不仅存在电场阈值和光能阈值下限,还存在光能阈值上限;本文提出了高倍增偶极畴模型对lock-on模式的高倍增机理进行分析,并根据该模型计算得到lock-on模式的电场和光能阈值上下限。最后采用激光二极管对光导开关进行实验测试,分析二极管参数变化对光导开关输出的影响,以实现电脉冲源的小型化设计。关于阵列辐射冲激电磁脉冲传输特性的研究,首先在圆形单元天线抽象模型的基础上,利用麦克斯韦方程组计算得到天线辐射冲激电磁脉冲的解析解,并由此得到天线辐射冲激电磁脉冲的物理意义以及天线轴线上能量传输特性的物理图像。在此基础上把单元天线看作点源,提出了适用于阵列天线的点源近似模型,对阵列辐射冲激电磁脉冲的传输特性进行研究,并通过实验证实了阵列冲激电磁脉冲的能量高效合成特性、波束聚焦特性,说明了阵列冲激雷达高分辨率的原因。另外,针对实验时冲激电磁脉冲能量随距离快速衰减的现象,用解析公式结合地面反射理论进行分析,得到的计算结果和实验测试结果完全吻合。对阵列冲激信号作用下目标的散射特性研究,采用和天线辐射冲激电磁脉冲类似的方法,根据均匀平面波垂直入射金属目标表面问题,给出了目标散射的物理实质和解析解,并以此为基础对介质目标散射特性进行分析。实验测试结果和解析计算结果相吻合。在文末给出了光导开关、Blumlein线、Vivaldi天线一体化的设计思路,进行了冲激雷达辐射系统实验测试,再次验证了阵列冲激电磁脉冲的合成特性。
[Abstract]:Impulse radar is a new ultra wideband radar technology, through the launch of the carrier free impulse detection or recognition of the target. The impulse signal with narrow pulse width, spectral component rich, impulse radar and continuous wave radar has great potential applications in comparison, range resolution, angular resolution, anti stealth, continuous wave radar penetration ability is better than the narrow band. This technology research on the array of impulse radar, the first is the research of impulse electric pulse signal source, electric pulse source requires not only high output power, and the trigger jitter is low, easy to realize synchronous output array; in addition to the array of red radiation the transmission characteristics of electromagnetic pulse excitation, according to the basic law of energy transmission, superposition, analysis of causes of high resolution array impulse radar; target scattering and impulse signal under the action of physical image. It provides a theoretical basis for the desired impulse radar detection. The impulse electric pulse source with high peak power and low jitter trigger demand, this paper selected the semi insulating GaAs photoconductive switches as electrical pulse source, using the method of combination of theoretical and Experimental Research on semi insulating GaAs photoconductive switch. Firstly, GaAs light material the absorption mechanism was analyzed through calculation, the semi insulating GaAs photoconductive switches for 1064 nm optical absorption is mainly due to the EL2 level of the photoionization absorption. The photoconductive switch were found in dark state test, dark resistance with the electric field change is not monotone decreasing, even increases with the increase of the electric field in a field range variation; hot electron effect combining with carrier and the impact ionization effect of impurities on dark resistance were analyzed. Secondly, in the 1064 nm laser pulse excitation, respectively, semi insulating GaAs light Test guide switch linear model and lock-on model. Results indicate that the linear mode switch sub linear volt ampere characteristic and output voltage saturation, light corresponding to the best working light linear photoconductive switch for output voltage saturation; compare the dark state of volt ampere and switch, when the electric field is greater than 3 kV/cm on state power should continue to increase with the increase of the electric field, basically shows linear photoconductive switch can not achieve high gain. In addition, semi insulating GaAs photoconductive switch lock (lock-on) model to test the threshold condition was found when the switch into not only the threshold electric field and energy threshold limit of lock-on mode, there is light threshold limit; this paper proposes and analyzes the mechanism of high gain high gain dipole domain model of lock-on mode, and lock-on mode is calculated according to the model The electric field and the energy threshold limit. Finally, by using laser diode test of photoconductive switch, analysis of the effect of diode parameters on the photoconductive switch output, to achieve the miniaturization design of electrical pulse source. On the array radiation transmission characteristic of electromagnetic pulse impulse excitation, based on circular antenna abstract model, using the Maxwell equations and solutions of electromagnetic pulse excitation analysis of antenna radiation and thus have rushed, the antenna radiation impulse electromagnetic pulse and the physical meaning of the physical image energy transmission characteristics of the antenna axis. On the basis of the antenna as a point source, point source suitable for antenna array approximation model, studied impulse transmission the characteristics of radiation induced electromagnetic pulse array, and verified the array impulse electromagnetic pulse energy efficient synthesis characteristics of beam focusing characteristics Of that array causes impulse radar with high resolution. In addition, the experiment of impulse electromagnetic pulse energy with fast distance attenuation phenomenon, analyzed by analytic formula combined with ground reflection theory, the computational results and experimental test results perfectly. To study the scattering characteristics of the target array thrusting shock signal. The antenna radiation and impulse electromagnetic pulse similar method, according to the uniform plane wave metal target surface, and the analytical solution and physical essence of target scattering is presented, and based on the medium target scattering characteristics are analyzed. The experimental results and analytical results coincide. In the Blumlein line are given in the end optical switch, Vivaldi antenna design, the integration of the impulse radar system test proves the array synthesis characteristic of electromagnetic pulse induced impulse.

【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN958

【参考文献】