【摘要】：時間反演是一種自適應(yīng)空時聚焦技術(shù)。時間反演后的聲波或電磁波可自適應(yīng)地匹配于傳輸信道,并有效地抑制甚至利用多徑干涉,提高信息傳輸可靠性和探測精度。近年來該技術(shù)已成功地應(yīng)用于目標探測、水聲通信、無損檢測、地震預(yù)報等方面,并成為電磁波領(lǐng)域中的一個研究熱點。本文的研究圍繞著基于時間反演的自適應(yīng)聚焦天線陣列展開,研究了時間反演電磁波的空時聚焦特性以及與傳播環(huán)境的相互作用機理,將其與陣列天線理論有機地結(jié)合起來,形成了基于時間反演的目標探測和波束形成算法,以及脈沖陣列天線的輻射分析設(shè)計方法。旨在為基于時間反演的陣列天線的研究、發(fā)展提供理論依據(jù)及新思路。首先,本文詳細介紹了時間反演電磁波的聚焦原理,在此基礎(chǔ)上建立了時間反演電磁波的實現(xiàn)模型和算法,并結(jié)合田口優(yōu)化算法對影響聚焦效果的因素進行了討論。從波動方程的時間反演對稱性和電波傳播的互易性出發(fā),分別采用格林函數(shù)和多徑信道模型分析了時間反演腔和時間反演鏡操作下的時間反演電磁波的聚焦原理。并將時間反演操作算子引入時域有限差分法中,結(jié)合田口優(yōu)化算法仿真分析了強散射環(huán)境下,時間反演鏡單元位置、記錄時間、記錄波形、陣列配置等因素對時間反演聚焦脈沖峰值的影響。這些工作為時間反演自適應(yīng)聚焦天線陣列的實現(xiàn)打下了基礎(chǔ)。其次,對脈沖陣列天線的分析和設(shè)計方法進行了研究,并根據(jù)脈沖天線收發(fā)波形的時間反演特征,提出了一種收發(fā)模型可方便地對陣元間的互耦進行分析。脈沖陣列天線允許適當降低對天線單元的要求,配合高速度的開關(guān)可有效地提高系統(tǒng)輻射性能,并使其具有波束形成和波束掃描的能力,是實現(xiàn)自適應(yīng)聚焦天線系統(tǒng)的一種有效的途徑。由于脈沖陣列相關(guān)理論還處于發(fā)展階段,其分析與設(shè)計存在著許多難點,因此論文提出了一些方法解決了部分問題。論文將點源分析方法和仿真計算相結(jié)合,提出了一種快速的脈沖陣列方向圖的計算方法,極大地提高了計算速度減小了內(nèi)存占用；還在時域推導(dǎo)了多路信號在空間實現(xiàn)最大化功率合成的條件,據(jù)此設(shè)計了一種陣饋拋物柱反射面天線,在軸向輸出超寬帶高功率的微波窄波束；另外,在超寬帶系統(tǒng)傳遞函數(shù)的基礎(chǔ)上,研究了脈沖天線在同一激勵下的收發(fā)波形,發(fā)現(xiàn)了二者之間的時間反演特征；基于此提出了脈沖陣列天線系統(tǒng)的收發(fā)模型,用于分離陣元的輻射波形,實現(xiàn)互耦分析和陣列設(shè)計。一維TEM喇叭陣列的分析設(shè)計算例充分表明了該模型的正確性和有效性。然后,將時間反演技術(shù)與拋物方程法相結(jié)合實現(xiàn)了大氣波導(dǎo)中輻射源的定位。波達方向估計是自適應(yīng)波束形成的先決條件,然而在大氣波導(dǎo)環(huán)境中,往往因多徑效應(yīng)造成接收信號畸變,導(dǎo)致常規(guī)的估計算法精度受到影響甚至無法工作。本文在仔細研究了拋物方程法和時間反演法的基本原理和實現(xiàn)算法的基礎(chǔ)上,提出了在初始場上加載時間反演電磁波的方法,采用時間反演拋物方程法定位大氣波導(dǎo)中的輻射源,仿真結(jié)果表明該方法和逆拋物方程法具有相同的定位精度。為了進一步提高該方法的實用性,又提出了將時間反演信息加載于反演陣列方向圖的方法,在保證了相同定位精度的同時,將原天線陣元數(shù)量減少為十分之一。最后,將時間反演技術(shù)應(yīng)用于波束形成算法當中,分別研究了近場的聚焦波束形成和遠場的波束形成算法。在近場采用時間反演波補償球面波的幅度和相位,實現(xiàn)了聚焦波束,并利用去自譜的聚焦算法得到了主波瓣更窄、旁瓣電平更低的波束。在遠場利用時間反演對信號的自適應(yīng)配對和聚焦能力,把接收信號的時反信息提取出來直接用作初始激勵場的幅相參數(shù),與迭代傅里葉變換法結(jié)合,優(yōu)化了陣列激勵的幅度,設(shè)計了超低旁瓣的多波束天線陣列。
[Abstract]:Time inversion is an adaptive space-time focusing technique. The acoustic wave or the electromagnetic wave after time inversion can be adaptively matched to the transmission channel, and the multi-path interference is effectively suppressed, and the reliability and the detection precision of the information transmission are improved. In recent years, the technology has been successfully applied to the aspects of target detection, underwater acoustic communication, non-destructive testing, earthquake prediction and so on, and has become a hot spot in the field of electromagnetic wave. In this paper, the time-inversion-based self-adaptive focusing antenna array is developed, and the time-to-time focusing characteristics of the electromagnetic wave and the interaction mechanism with the propagation environment are studied, and it is organically combined with the array antenna theory. The target detection and beam forming algorithm based on time inversion and the radiation analysis and design method of the pulse array antenna are formed. The purpose of this paper is to provide a theoretical basis and a new thought for the research and development of array antenna based on time inversion. Firstly, the focus principle of time-inversion electromagnetic wave is introduced in detail, and the realization model and algorithm of time-inversion electromagnetic wave are set up, and the factors that influence the focusing effect are discussed in combination with the field-opening optimization algorithm. Based on the time inversion symmetry of the wave equation and the reciprocity of the radio wave propagation, the focusing principle of the time inversion electromagnetic wave under the time inversion cavity and the time inversion mirror operation is analyzed by using the Green's function and the multi-path channel model, respectively. In this paper, the time inversion operation operator is introduced into the time domain finite difference method, and the influence of time inversion lens unit position, recording time, recording waveform, array configuration and other factors on the time inversion focusing pulse peak is analyzed by combining the field port optimization algorithm. These work lay a foundation for the time inversion of the adaptive focus antenna array. Secondly, the analysis and design method of the pulse array antenna is studied, and the mutual coupling between the elements can be conveniently analyzed based on the time inversion characteristics of the pulse antenna transmit/ receive waveform. The pulse-array antenna allows the proper reduction of the requirement of the antenna unit, and the high-speed switch can effectively improve the radiation performance of the system, and has the capability of beam forming and beam scanning, and is an effective way to realize the self-adaptive focusing antenna system. Because the theory of pulse array is still in the development stage, there are many difficulties in the analysis and design, so some methods have been put forward to solve some problems. By combining the point source analysis method and the simulation calculation, a rapid method for calculating the direction map of the pulse array is proposed, which greatly improves the calculation speed and reduces the memory occupation; and the condition that the multi-channel signal is used for maximizing the power synthesis in the space is also derived in the time domain, In addition, on the basis of the transfer function of the ultra-wideband system, the transmitting/ receiving waveform of the pulse antenna under the same excitation is studied, and the time inversion characteristics between them are found. The transmitting and receiving model of the pulse array antenna system is proposed, and the radiation waveform of the array element is separated, and the mutual coupling analysis and the array design are realized. The analysis and design of one-dimensional TEM horn array show the correctness and validity of the model. then, the time inversion technique and the parabolic equation method are combined to realize the positioning of the radiation source in the atmospheric waveguide. The DOA estimation is a prerequisite for adaptive beamforming, however, in the atmosphere waveguide environment, the distortion of the received signal is often caused by the multi-path effect, resulting in the accuracy of the conventional estimation algorithm being affected or even impossible to work. Based on a careful study of the basic principle and the implementation of the parabolic equation method and the time inversion method, a method for inverting the electromagnetic wave at the initial field loading time is proposed, and the radiation source in the atmospheric waveguide is positioned by the time inversion parabolic equation method, The simulation results show that the method and the inverse parabolic equation method have the same positioning accuracy. In order to further improve the practicability of the method, a method for loading the time inversion information in the inversion array direction map is proposed, and the number of the original antenna array elements is reduced to one-tenth while the same positioning accuracy is ensured. Finally, the time inversion technique is applied to the beam forming algorithm, and the beam forming and the beam forming algorithm of the near field are studied. In the near field, the time inversion wave is used to compensate the amplitude and phase of the spherical wave, the focus beam is realized, and the beam with lower main lobe and lower side lobe level is obtained by using the self-spectrum focusing algorithm. the self-adaptive pairing and focusing capability of the signal is inverted at the far field by using time, the time-inverse information of the received signal is extracted to be directly used as the amplitude phase parameter of the initial excitation field, combined with the iterative Fourier transformation method, the amplitude of the array excitation is optimized, An ultra-low sidelobe multi-beam antenna array is designed.
【學位授予單位】：西南交通大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN820.15

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