低副瓣数字端射阵列组阵研究

发布时间：2018-06-08 16:32

本文选题：端射天线 + 正交信号　；参考：《北京理工大学》2014年博士论文

【摘要】：端射天线结构简单，风阻小、成本低，作为雷达的发射和接收天线，可以大幅度缩减尺寸，实现雷达天线与载体的完美结合。但是端射天线相比较于各种口径天线其增益不高，这一缺点制约了它应用于需要窄波束、高增益的雷达天线方面。解决这一问题的办法就是以端射天线为单元组成端射天线阵列。但是端射天线阵列由于本身体制问题引入单元间复杂的互耦问题，导致端射天线组阵很难获得预期组阵高增益。通过拉大端射天线单元间距组阵可以获得高增益，但是引入栅瓣和高副瓣电平。解决的办法就是：提出基于最小二乘估计的虚拟内插阵元组阵新方法来实现栅瓣抑制，提出低副瓣波束合成算法进一步降低副瓣。本文的研究工作重点围绕数字端射天线低副瓣组阵问题展开,主要研究工作包括以下几个方面： 1、研究正交信号激励的数字端射阵列的基本原理。从阵列空域能量分布、抗截获能力、阵列综合方向图等方面开展正交信号阵列性能分析。相比常规相控阵，正交信号激励的端射阵列具有更低的截获概率，更灵活的辐射空域控制，方向系数、波瓣宽度、副瓣电平等阵列指标和常规相控阵指标一致。通过推导发射阵列和接收阵列相移关系，在常规的自适应波束形成算法的基础上，研究基于正交信号激励的自适应数字波束形成算法，给后面章节提供理论算法基础。 2、分析了互耦对于端射天线单元和端射阵列远场方向图的影响。对于常用的互耦计算效应的计算方法进行分析和比较，提出一种修正的DBF算法来研究互耦对于端射天线单元和端射阵列远场方向图的影响。该算法能够正确的计算互耦对于端射天线单元和端射阵列远场方向图的影响。仿真实例验证了该算法正确性。从信号去耦的角度，分析端射天线在侧射组阵时，正交信号激励对于单元间互耦的影响。仿真结果显示步进频正交信号激励的端射阵列对于单元间互耦的抑制效果不大。 3、开展了基于虚拟内插阵元技术的栅瓣抑制研究。当接收端射阵列单元间距为1.5时，提出基于最小二乘估计的虚拟内插阵元算法来抑制数字端射阵列的栅瓣。该算法是通过虚拟内插阵元的方式，使虚拟阵列的单元间距减小到0.5，从而使阵列栅瓣得到抑制。仿真实验结果证明了该算法的可行性。在实验样机上进行了虚拟内插阵元技术试验验证，测试结果验证了基于虚拟内插阵元技术抑制栅瓣的可行性和正确性。在相邻两个实端射天线单元间内插3个虚拟端射天线单元形成虚拟端射阵列，虚拟端射阵列保持实端射阵列高增益，峰值副瓣电平由-8.35dB下降到-18.25dB，栅瓣得到明显抑制。 4、开展了数字端射阵列低副瓣波束合成算法研究。首先研究干扰对消栅瓣抑制算法。该算法通过加入干扰信号的方式对方向图副瓣进行控制，但是在单元间距大于0.5时，在栅瓣处加入干扰信号，合成方向图时不能抑制栅瓣。因此在单元间距大于0.5时，根据正交信号激励的数字端射阵列的特点，，我们提出一种低副瓣波束合成算法。在发射阵列单元间距为1.5，接收阵列单元间距为0.5时，发射阵列出现栅瓣，我们可以在接收阵列方向图中与栅瓣对应的位置形成满足一定条件的低副瓣，这样在方向图相乘以后便不会形成高的副瓣，而接收阵列方向图的低副瓣值可通过加入干扰信号后DBF算法合成得到。仿真实验结果验证了算法的有效性。在发射阵列和接收阵列单元间距均为1.5，我们先通过第4章研究的在发射和接收阵列加入虚拟内插阵元的方法抑制栅瓣，然后再利用第5章的低副瓣波束合成算法来进一步降低副瓣电平。采用该算法后，接收阵列副瓣电平由-18.25dB下降到-28.12dB，双程阵列副瓣电平由-15.53dB下降到-32.21dB。
[Abstract]:The end ejection antenna is simple in structure, small in wind resistance and low in cost. As a radar transmitting and receiving antenna, it can greatly reduce the size of the antenna and realize the perfect combination of the radar antenna and the carrier. However, the end shooting antenna has a low gain compared with the various aperture antennas. This disadvantage restricts its application to the radar antenna which needs narrow beam and high gain. The way to solve this problem is to use the end shooting antenna as an antenna array. However, the end ejection antenna array leads to the complex mutual coupling problem between the units due to its own system problem, which leads to the difficulty of obtaining the expected high gain of the expected array array. The solution of gate valve and high sidelobe level is to propose a new method of virtual inner array tuple array based on least square estimation to suppress the gate lobe, and propose a low sidelobe beamforming algorithm to further reduce the sidelobe.
The research work in this paper focuses on the low sidelobe array problem of digital end fire antenna. The main research work includes the following aspects:
1, the basic principle of digital end shooting array excited by orthogonal signal is studied. The performance analysis of orthogonal signal array is carried out from the space domain energy distribution, the anti interception ability, the array synthesis direction and so on. Compared with the conventional phased array, the end shooting array excited by the orthogonal signal has the lower intercept probability, the more flexible radiation space control, the direction system. The number, the lobe width, the sidelobe level and other array indexes are the same as the conventional phased array. By deriving the relationship between the transmit array and the received array phase shift, the adaptive beamforming algorithm based on the orthogonal signal excitation is studied on the basis of the conventional adaptive beamforming algorithm, which provides the theoretical algorithm basis for the following chapters.
2, the influence of mutual coupling on the end fire antenna element and the far field pattern of end ejection array is analyzed. A modified DBF algorithm is proposed to study the influence of mutual coupling on the end fire antenna element and the far field pattern of end ejection array. The simulation example shows the correctness of the algorithm. From the angle of the signal decoupling, the effect of the orthogonal signal excitation on the mutual coupling between the units is analyzed from the angle of the signal decoupling. The simulation results show that the end shooting array of the step frequency orthogonal signal excitation is used to suppress the mutual coupling among the units. The effect of the system is not very good.
3, the gate flap suppression based on virtual interpolation array is developed. When the spacing of the receiving end array unit is 1.5, a virtual interpolated array element algorithm based on the least square estimation is proposed to suppress the gate lobe of the digital end array. This algorithm makes the cell spacing of the virtual array reduced to 0.5 by the virtual interpolation array element. The array gate flap is suppressed. The simulation experiment results demonstrate the feasibility of the algorithm. The experimental verification of the virtual interpolation array technique is carried out on the experimental prototype. The test results verify the feasibility and correctness of the suppression of the gate flap based on the virtual interpolation array technology. 3 virtual end shooting antenna units are interpolated between the two adjacent real terminal line units. The virtual end fire array is formed, the virtual end fire array keeps the high gain of the real end array, and the peak sidelobe level decreases from -8.35dB to -18.25dB, and the gate lobe is obviously suppressed.
4, research on the low sidelobe beam synthesis algorithm of digital end shooting array is carried out. Firstly, the interference cancellation gate suppression algorithm is studied. The algorithm controls the side lobe of the pattern by adding interference signals, but when the unit spacing is greater than 0.5, the interference signal is added to the gate flap, and the gate flap can not be suppressed when the direction map is combined. When the distance is greater than 0.5, we propose a low sidelobe beam synthesis algorithm based on the characteristics of the digital end shooting array excited by the orthogonal signal. When the spacing of the array unit is 1.5 and the spacing of the receiving array unit is 0.5, the array lobe appears in the array. We can form a certain condition in the position corresponding to the gate valve in the received array direction. The low sidelobe will not form a high sidelobe after multiplying the direction map, and the low sidelobe value of the received array pattern can be synthesized by the DBF algorithm after adding interference signals. The simulation results verify the effectiveness of the algorithm. The space between the transmitter array and the receiving array unit is 1.5, and we first studied in the fourth chapter. This algorithm is used to reduce the sidelobe level further by using the low sidelobe beam synthesis algorithm in fifth chapters. After this algorithm, the received array sidelobe level is reduced from -18.25dB to -28.12dB, and the dual path array sidelobe level is reduced from -15.53dB to -32.21dB.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN957.2

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