本文選題：軌道角動量 + 渦旋電磁波　； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院國家空間科學(xué)中心)》2017年碩士論文

【摘要】：軌道角動量是渦旋電磁波的新自由度,不同的軌道角動量可以構(gòu)成無窮維模態(tài)空間中的正交基,有多路復(fù)用以提高頻譜效率解決電磁頻譜擁擠問題的潛力。渦旋電磁波的幅度具有第一類貝塞爾函數(shù)的形式,輻射場對于成像區(qū)域有著不同的權(quán)重,容易突破天線孔徑實(shí)現(xiàn)天線波束內(nèi)的超分辨率成像。本文的目的是對基于均勻圓形天線陣的渦旋電磁波的產(chǎn)生與接收進(jìn)行誤差分析,得出能夠準(zhǔn)確判別軌道角動量模態(tài)的誤差閾值,明確軌道角動量各接收方案的接收條件,為渦旋電磁波的產(chǎn)生與接收提供技術(shù)參考。同時(shí)對渦旋電磁波在雷達(dá)探測與成像方面的應(yīng)用潛力進(jìn)行探索與評估。本文首先研究了天線陣元激勵(lì)幅度和相位存在高斯分布誤差、量化誤差、單個(gè)陣元誤差以及均勻圓形天線陣的陣元個(gè)數(shù)對所產(chǎn)生的渦旋電磁波的幅相特征的影響,利用相位梯度法計(jì)算了軌道角動量模態(tài)并給出準(zhǔn)確辨認(rèn)模態(tài)時(shí)的各誤差閾值。仿真實(shí)驗(yàn)顯示,在各類激勵(lì)幅度和相位誤差下,渦旋電磁波有效幅射區(qū)域的幅度會由環(huán)狀變得不規(guī)則,相位在有效輻射區(qū)域內(nèi)保持良好,而在幅度強(qiáng)度很低的中心和邊緣出現(xiàn)了模糊與惡化。實(shí)驗(yàn)結(jié)果說明,渦旋電磁波對各類激勵(lì)幅度和相位誤差具有良好的抗干擾特性。論文對均勻圓形天線陣的接收方案進(jìn)行了誤差分析,分析了均勻圓形天線陣接收陣列與發(fā)射陣列不平行的情況下,渦旋電磁波的幅度與相位的改變。結(jié)果表明,渦旋電磁波對均勻圓形天線陣有傾斜角的誤差具有很強(qiáng)的敏感性,甚至在3度的傾斜角誤差下渦旋電磁波的相位分布已不能分辨出軌道角動量的模態(tài)。另外,明確了渦旋電磁波的各接收方案的接收條件。最后,論文對渦旋電磁波在雷達(dá)探測與成像中的應(yīng)用進(jìn)行了研究。根據(jù)渦旋電磁波的幅度中空特征選擇了側(cè)視成像體制,建立了渦旋電磁波的成像模型,利用最小二乘的關(guān)聯(lián)算法成像。仿真結(jié)果表明,同參數(shù)下與傳統(tǒng)信號的成像分辨率相比,渦旋電磁波將分辨率提高了1.8倍。對渦旋電磁波的成像結(jié)果進(jìn)行了評價(jià):由于渦旋電磁波幅度的圓對稱以及中空結(jié)構(gòu)特征,對成像分辨率的提升能力有限;渦旋電磁波所形成的信號參考矩陣條件數(shù)很高,表明具有較大的病態(tài)性;隨著信噪比的增加,成像結(jié)果以及均方根誤差均會有一定的改善。
[Abstract]:Orbital angular momentum is a new degree of freedom of vortex electromagnetic wave. Different orbital angular momentum can form the orthogonal basis in infinite dimensional mode space and has the potential of multiplexing to improve the spectral efficiency to solve the problem of electromagnetic spectrum congestion. The amplitude of vortex electromagnetic wave has the form of Bessel function of the first kind, and the radiation field has different weights for the imaging region, so it is easy to break through the antenna aperture to realize super-resolution imaging in the antenna beam. The purpose of this paper is to analyze the error of vortex electromagnetic wave generation and reception based on uniform circular antenna array, to obtain the error threshold which can accurately distinguish the orbital angular momentum mode, and to determine the receiving conditions of each receiving scheme of orbital angular momentum. It provides a technical reference for the generation and reception of vortex electromagnetic wave. At the same time, the application potential of vortex electromagnetic wave in radar detection and imaging is explored and evaluated. In this paper, the effects of Gao Si distribution error, quantization error, single element error and the number of array elements of uniform circular antenna array on the amplitude and phase characteristics of vortex electromagnetic wave are studied. The phase gradient method is used to calculate the orbital angular momentum modes and the error thresholds for identifying the modes are given. The simulation results show that the amplitude of the effective radiation region of vortex electromagnetic wave changes from annular to irregular under various excitation amplitude and phase error, and the phase keeps well in the effective radiation region. At the center and edge where the amplitude intensity is very low, there is blur and aggravation. The experimental results show that the vortex electromagnetic wave has good anti-interference characteristics to all kinds of excitation amplitude and phase error. In this paper, the error analysis of the receiving scheme of uniform circular antenna array is carried out, and the amplitude and phase of vortex electromagnetic wave are analyzed when the receiving array of uniform circular antenna array is not parallel to the transmitting array. The results show that the vortex electromagnetic wave is very sensitive to the error of the uniform circular antenna array with inclination angle, and even the phase distribution of the vortex electromagnetic wave can not distinguish the orbital angular momentum mode under the angle error of 3 degrees. In addition, the receiving conditions of each receiving scheme of vortex electromagnetic wave are determined. Finally, the application of vortex electromagnetic wave in radar detection and imaging is studied. According to the amplitude and hollow characteristic of vortex electromagnetic wave, the lateral imaging system is selected, the imaging model of vortex electromagnetic wave is established, and the least square correlation algorithm is used to image the image. The simulation results show that the resolution of the vortex electromagnetic wave is 1.8 times higher than that of the conventional signal under the same parameters. The imaging results of the vortex electromagnetic wave are evaluated. Due to the circular symmetry of the amplitude of the vortex electromagnetic wave and the hollow structure, the lifting ability of the imaging resolution is limited, and the condition of the signal reference matrix formed by the vortex electromagnetic wave is very high. With the increase of SNR, the imaging results and the root mean square error will be improved to some extent.
【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院國家空間科學(xué)中心)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN820.15

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本文編號：1807406