本文關(guān)鍵詞：陣列沖激雷達關(guān)鍵技術(shù)研究　出處：《電子科技大學》2017年博士論文　論文類型：學位論文

  更多相關(guān)文章： 陣列沖激雷達 半絕緣GaAs光導開關(guān) 高倍增偶極疇模型 點源近似模型 沖激電磁脈沖能量合成

【摘要】：沖激雷達是一種新興的超寬帶雷達技術(shù),通過發(fā)射無載波沖激脈沖對目標進行探測或識別。由于沖激信號的脈沖寬度窄,頻譜分量豐富,沖激雷達和連續(xù)波雷達相比有巨大的應用潛力,在距離分辨率、角分辨率、反隱身、穿透能力等方面都優(yōu)于窄帶的連續(xù)波雷達。本文關(guān)于陣列沖激雷達的技術(shù)研究,首先是對沖激電脈沖信號源的研究,電脈沖源不僅要求輸出功率高,同時要求觸發(fā)抖動低,易于實現(xiàn)陣列的同步輸出;另外對陣列輻射沖激電磁脈沖的傳輸特性進行研究,根據(jù)其能量傳輸、疊加的基本規(guī)律,分析陣列沖激雷達高分辨率的原因;最后對沖激信號作用下目標散射的物理圖像進行研究,期望對沖激雷達目標探測提供一定的理論基礎。針對沖激電脈沖源高峰值功率低觸發(fā)抖動的需求,本文選用半絕緣GaAs光導開關(guān)作為電脈沖源,采用理論和實驗相結(jié)合的方法對半絕緣GaAs光導開關(guān)進行研究。首先對GaAs材料的光吸收機理進行分析,通過計算發(fā)現(xiàn)半絕緣GaAs光導開關(guān)對1064 nm的光吸收主要是由于EL2能級的光致電離吸收。接下來對光導開關(guān)進行暗態(tài)測試時發(fā)現(xiàn),暗電阻隨電場變化并非單調(diào)減小,在某段電場范圍內(nèi)甚至會隨電場增加而增加;結(jié)合載流子的熱電子效應以及雜質(zhì)的碰撞電離效應對暗電阻的變化規(guī)律進行分析。其次,在1064 nm激光脈沖激勵下,分別對半絕緣GaAs光導開關(guān)的線性模式和lock-on模式進行了實驗測試。線性模式下開關(guān)的亞線性伏安特性和輸出電壓飽和特性表明,線性光導開關(guān)的最佳工作光能為輸出電壓開始飽和時對應的光能;通過與開關(guān)的暗態(tài)伏安特性進行對比發(fā)現(xiàn),當電場大于3 kV/cm時開態(tài)電竟然隨電場增加繼續(xù)增加,從根本上說明了線性光導開關(guān)無法實現(xiàn)高增益的原因。另外,對半絕緣GaAs光導開關(guān)鎖定(lock-on)模式閾值條件進行實驗測試時發(fā)現(xiàn),開關(guān)進入lock-on工作模式不僅存在電場閾值和光能閾值下限,還存在光能閾值上限;本文提出了高倍增偶極疇模型對lock-on模式的高倍增機理進行分析,并根據(jù)該模型計算得到lock-on模式的電場和光能閾值上下限。最后采用激光二極管對光導開關(guān)進行實驗測試,分析二極管參數(shù)變化對光導開關(guān)輸出的影響,以實現(xiàn)電脈沖源的小型化設計。關(guān)于陣列輻射沖激電磁脈沖傳輸特性的研究,首先在圓形單元天線抽象模型的基礎上,利用麥克斯韋方程組計算得到天線輻射沖激電磁脈沖的解析解,并由此得到天線輻射沖激電磁脈沖的物理意義以及天線軸線上能量傳輸特性的物理圖像。在此基礎上把單元天線看作點源,提出了適用于陣列天線的點源近似模型,對陣列輻射沖激電磁脈沖的傳輸特性進行研究,并通過實驗證實了陣列沖激電磁脈沖的能量高效合成特性、波束聚焦特性,說明了陣列沖激雷達高分辨率的原因。另外,針對實驗時沖激電磁脈沖能量隨距離快速衰減的現(xiàn)象,用解析公式結(jié)合地面反射理論進行分析,得到的計算結(jié)果和實驗測試結(jié)果完全吻合。對陣列沖激信號作用下目標的散射特性研究,采用和天線輻射沖激電磁脈沖類似的方法,根據(jù)均勻平面波垂直入射金屬目標表面問題,給出了目標散射的物理實質(zhì)和解析解,并以此為基礎對介質(zhì)目標散射特性進行分析。實驗測試結(jié)果和解析計算結(jié)果相吻合。在文末給出了光導開關(guān)、Blumlein線、Vivaldi天線一體化的設計思路,進行了沖激雷達輻射系統(tǒng)實驗測試,再次驗證了陣列沖激電磁脈沖的合成特性。
[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.

【學位授予單位】：電子科技大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TN958

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