【作者】 张雪芹；

【导师】 王均宏；

【作者基本信息】 北京交通大学 ， 电磁场与微波技术， 2008， 博士

【摘要】 天线的隐身与反隐身已经成为一个重要的课题,现有研究大多是基于连续波工作状态。而时域脉冲包含有极宽的频谱,被认为是一种有效的反隐身途径。目前技术已经能够制造出纳秒级、峰值功率在几个GW的脉冲源,脉冲探测装备的实用化已成为可能。因此,研究天线在强脉冲作用下的散射特性、特征及其与天线结构之间的关系显得非常重要和紧迫,这些信息对天线的隐身与反隐身非常重要。本文将天线阵列的时域散射作为课题,旨在从机理上研究天线的时域散射特性及其与结构之间的关系,研究减小天线时域散射的方法和途径。本文的主要工作和创新点如下:1.研究了现有时域天线辐射及散射参数的定义,提出了几种可以用于描述天线时域散射特性的参量。2.组建了并行机,实现了FDTD程序的并行化,并研究了并行计算效率,结果表明基于MPI设计的并行FDTD程序,能够有效计算较大型天线阵列的时域散射特性。3.首次系统地研究了对数周期天线、平面振子天线阵列、带有反射面的平面振子天线阵列的时域散射特性,分析了不同馈电方式、不同脉冲宽度、不同入射方向、以及不同极化等情况下的散射脉冲峰值、能量分布以及频谱的变化规律。4.研究了偶极天线阵列的时域散射机理,分析了入射方向不同时散射脉冲的波形特征和频谱特征与天线阵列结构的内在联系;研究了能够通过后向散射场特征识别天线阵列大小的入射角度的变化范围、及其与入射脉冲宽度的关系;采用时频分析技术分析了不同宽度脉冲入射时后向散射场的时频特征。5.提出了反射面边缘渐变加载、锯齿化、以及改为楔型等三种减小带有反射面的振子天线阵列时域散射场峰值的方法,结果表明反射面边缘渐变加载和锯齿化两种方法对抑制散射场峰值效果明显。6.研究了微带阵列天线在探针馈电和微带线馈电两种情况下的时域散射特性,采用散射场分离算法研究了微带贴片阵列和地板各自对散射场的贡献,结果表明带有窄带馈电网络的微带天线阵列的时域散射特性与没有馈电网络的开路阵列的情况基本一致,并且非谐振频率时的散射主要来自地板的贡献。更多还原

【Abstract】 The stealth and anti-stealth techniques of antenna has become an important subject. The conventional investigations on this subject are mainly based on continuous wave. Due to the property of ultra-wide-band, time-domain impulse is considered as an efficient way of anti-stealth. Currently, impulse sources with duration of nanosecond and peak power of several GW can be manufactured, which make it possible to utilize impulse detection devices for practical applications. Therefore, it is emergent and important to study the scattering characteristics of antenna illuminated by strong impulse and to find the relationship between these characteristics and antenna structure. These kinds of information are of great importance on the study of stealth and anti-stealth. With the subject of time-domain scattering of antenna array, this dissertation is aimed to study the time-domain scattering mechanism of antenna scattering and find the relationship between scattering characteristics and antenna structure, and look for ways to reduce the time-domain scattering.The main work and innovation points in this dissertation include:1. By studying the available definitions of radiating and scattering parameters of antennas in time-domain, several parameters are proposed which can be used to describe the time-domain scattering characteristics of antenna.2. Parallel computer cluster has been constructed, and the FDTD code was also modified into parallel format. In addition, the efficiency of parallel calculation has been studied. The results indicate that parallel FDTD code based on MP1 can calculate the time-domain scattering of large antenna array efficiently.3. Time-domain scattering characteristics of log-periodic antenna (PLA), plane dipole antenna array with and without reflectors are studied systematically for the first time. Variations of scattering impulse peak value, energy distribution and frequency spectrum with different feeding modes, impulse width, incident directions and polarizations are analyzed.4. Time-domain scattering mechanism of dipole antenna array has been studied. The interrelationship between the scattering impulse waveform, spectrum and array structure is analyzed. The range of impulse incident angle, within which the size of the array can be identified according to the backscattered field, is studied. The relationship between the angle range and the impulse width was also studied. Based on the time-frequency technique, the time-frequency characteristics of backscattered field with different incident impulse width are analyzed.5. Three methods were proposed to reduce the peak value of time domain scattering field of dipole antenna array with reflector, which are, the taper loading in reflector edges, toothed edges and wedged edges of the reflector. The results demonstrate that the effect on suppressing the peak value of scattering field is dramatic by employing the methods of taper loading edges and toothed edges.6. Time-domain scattering characteristics of microstrip antenna array with probe feeding and microstrip line feeding have been studied. Contributions of microstrip patches and ground plane to the scattering field are analyzed individually by using the method of scattering field separation. The results show that little difference on the time-domain scattering characteristics can be found between the microstrip antenna array with narrowband feeding network and the array without feeding network but open-circuit each element. It is also found that the scattering outside resonant frequency is mainly contributed by the ground plane.更多还原