本文關(guān)鍵詞： 無源探測定位 波達方向估計 梯度折射率透鏡 電磁諧振器 高阻抗電磁表面　出處：《哈爾濱工業(yè)大學》2014年碩士論文　論文類型：學位論文

【摘要】：作為無源探測定位技術(shù)的核心，波達方向估計技術(shù)有著極其廣闊的應(yīng)用前景。但傳統(tǒng)的波達方向估計技術(shù)為了獲得較為精確的結(jié)果，通常都會在系統(tǒng)前端設(shè)置數(shù)量眾多的天線陣元，這就使系統(tǒng)的構(gòu)造復雜體積龐大，制造和維護成本較高，從而制約了波達方向估計技術(shù)的實際應(yīng)用。龍伯透鏡作為梯度折射率透鏡的一種實現(xiàn)小型化的形式，可以將入射的平面波匯聚到透鏡邊緣的一個焦點上，非常適合作為多波束天線。本文利用梯度折射率透鏡的特殊電磁特性，將其應(yīng)用到波達方向估計技術(shù)中，減少系統(tǒng)所需接收天線的數(shù)量要求，降低成本和算法難度。本文的主要內(nèi)容可分為如下幾部分： 首先，本文基于等效媒質(zhì)理論，通過推導得出了利用S參數(shù)提取等效電磁參數(shù)的方法。提出了一種新型的立體十字型結(jié)構(gòu)作為梯度折射率超材料的單元，并計算出了其結(jié)構(gòu)尺寸與電磁參數(shù)的對應(yīng)關(guān)系。在此基礎(chǔ)設(shè)計出三維結(jié)構(gòu)的梯度折射率透鏡。仿真結(jié)果表明，在平面波入射情況下，該透鏡在X波段能夠?qū)崿F(xiàn)良好的匯聚效果。 其次，本文將電磁諧振器引入到梯度折射率透鏡的設(shè)計中來。利用電磁諧振器在低于諧振頻率時，其等效電磁參數(shù)基本保持一致的特性，通過仿真計算得到了其電磁參數(shù)隨結(jié)構(gòu)尺寸的變化規(guī)律。在此基礎(chǔ)上設(shè)計出了低剖面型的二維結(jié)構(gòu)的梯度折射率透鏡。此外還提出了一種基于高阻抗電磁表面的梯度折射率透鏡，通過調(diào)整表面波阻抗來控制電磁波的傳播路徑。由于利用PCB制作工藝即可完成制作，具有透鏡制作成本較低、體積小的特點。 最后對波達方向估計進行算法的設(shè)計。由于梯度折射率透鏡可以很好的將電磁波匯聚到一點，因此可以通過最大信號法來實現(xiàn)對波達方向的測量。在透鏡邊緣放置信號接收裝置，旋轉(zhuǎn)透鏡的同時檢測接收到的信號幅度，當幅值最大時，，接收裝置和透鏡中心所指向的方向就是波達方向。該算法簡單易行，而且仿真和實際測量結(jié)果顯示其精確度較高。
[Abstract]:As the core of passive detection and location technology, DOA estimation technology has a very broad application prospects, but traditional DOA estimation technology in order to obtain more accurate results. Usually, a large number of antenna elements are set in the front end of the system, which makes the structure of the system complex and huge, and the cost of manufacturing and maintenance is high. Therefore, the practical application of DOA estimation is restricted. As a miniaturized form of gradient index lens, Lomber lens can converge the incident plane wave to a focal point on the edge of the lens. It is very suitable as a multi-beam antenna. In this paper, the gradient index lens is applied to the DOA estimation by using the special electromagnetic characteristics of the gradient index lens, which can reduce the number of receiving antennas required by the system. The main contents of this paper can be divided into the following parts: Firstly, based on the theory of equivalent medium, the method of extracting equivalent electromagnetic parameters by using S parameters is derived, and a new type of stereoscopic cross structure is proposed as the element of gradient index metamaterials. The corresponding relationship between the structure size and electromagnetic parameters is calculated. On this basis, the gradient index lens of three-dimensional structure is designed. The simulation results show that the incident plane wave is the case. The lens can achieve a good convergence effect in X band. Secondly, the electromagnetic resonator is introduced into the design of the gradient index lens. The equivalent electromagnetic parameters of the electromagnetic resonator are basically consistent when the resonance frequency is lower than the resonant frequency. The variation of electromagnetic parameters with structure size is obtained by simulation. Based on this, a low profile gradient refractive index lens with two-dimensional structure is designed. In addition, a kind of high impedance electromagnetic surface based gradient index lens is proposed. Gradient index lens. The transmission path of electromagnetic wave can be controlled by adjusting the surface wave impedance. Because the fabrication process can be completed by using PCB, it has the characteristics of low cost and small volume of lens fabrication. Finally, the algorithm of DOA estimation is designed. Because the gradient index lens can converge the electromagnetic wave to a point well. Therefore, the maximum signal method can be used to measure the direction of arrival. A signal receiving device is placed at the edge of the lens, and the amplitude of the received signal is detected while rotating the lens, when the amplitude is the largest. The direction of the receiver and the center of the lens is the direction of arrival. The algorithm is simple and feasible, and the simulation and actual measurement results show that the accuracy of the algorithm is high.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN95

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