基于HFSS的机载天线方向图研究

简要分析了机体结构对机载天线方向图的影响,并采用HFSS软件的高频积分方程(HFSS-IE)求解器对甚高频(VHF)频段的天线进行仿真,对比不同位置处天线方向图变化,分析了方向图变化的产生原因,可在早期飞机研发设计中为天线布置提供参考。     

FEKO在直升机天线布局中的应用

电磁仿真软件FEKO具有强大的电磁场计算分析能力。以直升机载航管应答天线和无线电高度表天线为例,研究了FEKO在直升机天线布局设计中的应用,给出了FEKO中的模型建立方法,通过仿真计算天线辐射方向图和隔离度及其分析,说明FEKO可完成天线布局的优化设计。研究中的试验测量结果与仿真计算结果基本吻合,验证了FEKO进行直升机天线布局仿真方法的合理性和可行性。     

基于天线安装的菱形翼无人机翼型优化设计

以菱形翼布局高空长航时(HALE)传感器无人机研究为背景,分析了翼型内部安装平面相控阵雷达天线的基本原理。通过推导雷达探测性能的估算方程,建立了在翼型中安装平面相控阵雷达天线的数学模型。采用数值模拟的方法,对典型雷诺数下的RAE2822翼型的气动特性进行了研究并与试验数据进行了对比,验证了使用有限体积法k-ωSST(Shear Stress Transport)湍流模型求解雷诺平均Navier-Stokes方程在这一状态下的可靠性和适用性;同时对不同厚度的NACA 64A系列翼型的流场结构和流动机理进行了分析,在此基础上提出了一种满足平面相控阵雷达天线安装情况下翼型的优化设计思想。优化结果验证了这一设计思想的可行性。     

相控阵雷达天线模型及仿真

阐述了相控阵天线仿真的重要性,指出了相控阵天线仿真的主要困难。提出了一种利用阵因子、方向性因子和旁瓣抑制因子分别解决仿真波束形状、天线增益、方向图旁瓣及其变化等3大问题,并进行综合建模和仿真,给出了综合后的仿真模型。该仿真模型保证了理论方面的精度,优化和减少了仿真计算步骤和计算量。利用该仿真模型,给出了宙斯盾系统的AN／SPY-1D雷达天线的仿真计算实例。     

相控阵雷达导引头波束稳定技术研究

 相控阵雷达导引头已成为新型空空导弹制导系统的首选,相控阵雷达导引头应用在空空导弹上需要首先解决导引头波束稳定的技术难题。本文基于波束指向在惯性空间不变性原理提出一种相控阵雷达导引头波束稳定算法,对影响相控阵雷达导引头隔离度性能的主要因素进行了仿真分析。仿真结果表明:该算法可以实现相控阵雷达导引头波束惯性空间指向稳定并且满足工程应用要求;通过减小速率陀螺数据周期和波束控制周期,及引入速率陀螺传输延时补偿算法可以提高导引头的隔离度性能。     

弹载共形相控阵天线拓扑结构分析

以弹载多模复合制导雷达导引头为应用背景,在未考虑极化的情况下,首先建立了任意有向阵列的方向图函数;然后,采用同心圆等角度、同心圆等间距以及矩形栅格 3种不同配置方式,建立了锥面共形相控阵天线模型,推导了不同配置方式下天线阵列方向图函数;通过比较其方位面及俯仰面的副瓣电平,得出结论:同心圆等间距配置方式是锥面共形相控阵雷达导引头天线单元的最优配置方式。     

子阵级应用延迟线对相控阵天线带宽改善的分析

采用频率无关移相器的相控阵天线的波束指向会随频率发生变化.实时延迟线是提高宽带相控阵天线指向精度的重要方法.分析了平面相控阵天线波束指向随频率改变而产生漂移的现象,理论分析和仿真结果均表明,当频率改变时,平面相控阵天线的波束指向仅在俯仰角面发生漂移,而在方位角的指向不变.详细讨论采用子阵分割技术,并在子阵级别用实时延迟线,单元内采用移相器的混合波束控制技术.结果表明,这种方法可以有效扩展相控阵天线的带宽.     

海面低飞情况下机载航管二次雷达覆盖研究

二次雷达较之一次雷达有许多优点，使其在军用和民用领域得到广泛应用。但当装有航管二次雷达的飞机在海面低飞时，会出现常见的多径效应现象。文章详细分析了飞机机体和海面对航管二次雷达方向图的影响，并利用HFSS软件对飞机在海面低飞时航管二次雷达方向图进行仿真。结果表明，海面影响航管二次雷达的方向图并导致根据其分叉变形，根据平面对天线方向图的影响及其计算公式，对不同飞行高度的方向图进行了计算，得出了在海面低飞时的最佳飞行高度。     

相控阵雷达探测性能计算研究

提出了一种相控阵雷达波位的编排方法,该方法采用第一指向角作为法向波束宽度,使得雷达波位间隙率为0、重叠率很小。通过对指向角大的波位进行驻留时间补偿,使得脉冲积累数随波束指向角增加而增大,探测性能随指向角变化差别不大。以波位编排和边缘不出现栅瓣为条件,可以估算相控阵雷达结构参数。在此基础上,初步建立了相控阵雷达探测性能的计算过程。对简单目标的仿真计算表明,计算方法合理,计算结果可信。     

基于相控阵雷达天线俯仰多波位相扫的设计与应用

分析研究了如何设计平面相控阵雷达天线多波位相扫的基本原理,提出了36行平面相控阵雷达天线在俯仰上实现多波位发射波束、接收波束形成与展宽方法.通过微波暗室的测试,天线技术指标完全达到了平面相控阵雷达天线多波位相扫的技术要求,实现了一维相控阵面高增益、高灵敏度、低噪声、大动态范围技术指标.     

Robust space-time adaptive processing for airborne radar in nonhomogeneous clutter environments

Space-time adaptive processing (STAP) holds tremendous potential for the new generation airborne surveillance radar, in which the phased array antennas and pulse Doppler processing mode are adopted. A new STAP approach using the multiple-beam and multiple Doppler channels is presented here for airborne phased array radar. The approach with space-time multiple-beam (STMB) architecture is robust to array errors and has very low system degrees of freedom (DOFs). Hence, it has low sample support requirement and it is very suitable for the practical planar phased array radar under nonhomogeneous clutter environments. Meanwhile, a new nonhomogeneous detector (NHD) based on the correlation dimension (CD) is also proposed here, which is used as an effective method to screen tracing data prior to detection processing. It can further improve the performance of the STAP approach in the severely nonhomogeneous clutter environments. Therefore, a scheme that incorporates the correlation dimension nonhomogeneity detector (CD-NHD) with the STMB is recommended, which we term CD-NHD-STMB. The experimental simulation results indicate that: 1) the STMB processor is robust to array element error and has high performance under nonhomogeneous clutter environments; 2) the CD-NHD is also effective on the nonhomogeneous clutter. As a result, the CD-NHD-STMB scheme is robust to array element error and nonhomogeneous clutter, and therefore available for airborne phased array radar applications.     

Noise-correlating radar based on retrodirective antennas

A new retrodirective antenna-based search radar system has been introduced. The suggested system uses a noise correlation technique to detect the presence and the direction of the target. Simulation and analytical results show an order of magnitude improvement in acquisition time of the radar when compared with a phased array antenna-based radar system with the same specifications, except transmit power. To the best knowledge of the authors, no radar of a comparable acquisition time has been designed to this date. Power versus acquisition time tradeoff has been compared with a phased array radar for evaluating performance of the system. The radar is self-tracking due to retrodirectivity of the antenna array, and is much easier to implement, as it does not require any phase shifters etc.     

Ka波段高增益圆极化机载微带天线阵的设计与实现

设计、分析、制作了一种工作在Ka波段的4单元高增益、圆极化机载微带天线阵列。利用顺序旋转阵列和串并馈方式的微带线网络馈电,显著改善了天线的轴比带宽和驻波带宽,减少了馈线损耗,实现了高增益。采用L型微带调配枝节对贴片单元进行匹配,便于组阵,解决了阵列空间布局不合理的难题;馈电网络和天线单元集成在同一介质基板上,易于加工和制作。测试结果表明:该天线阵具有高增益和良好的圆极化特性,从而证实了该方法的正确性和实用性。本文所设计的天线由于具有体积小、质量轻、结构紧凑、易于集成等优点,在机载相控阵雷达以及卫星通信系统中具有很好的应用前景。     

Active transmitting phased antenna arrays

The benefits of using transmitting phased array antennas for radar systems are examined. Accurate performance prediction for the transmitting phased array antennas requires theories describing both the antenna system and the power generation devices. These theories were created and applied to the design and performance evaluation of the Russian 3-D mobile solid-state surveillance radar 67N6E (GAMMA-DE), a PAA designed for long-range air defense.     

相控阵雷达搜索方式下波位编排与优化

分析不同波位编排方式对相控阵雷达能量需求与搜索性能的影响,给出了搜索方式下较为优化的波位编排方式。然后在分析相控阵雷达波束展宽效应的基础上,提出了非均匀划分扫描空域并对波束展宽效应进行补偿的方法,对波位编排方式进一步优化。最后利用该方法仿真分析了波束宽度与天线增益的变化,结果表明可有效补偿波束展宽效应带来的影响。     

Analysis of array errors and a short-time processor in airbornephased array radars

Array errors are inherent in a realistic phased array radar system. The influence of array errors on the clutter degrees of freedom and the clutter subspace in an airborne phased array radar is analyzed. Based on the presented theoretic results, a method of short-time processing followed by coherent integration is proposed for clutter suppression in airborne phased array radars. It can approximate the two-dimensional optimal processor well even in the presence of array errors, clutter fluctuations and aircraft drift, with a considerable saving in computations     

Electronically steerable plasma mirror based radar-concept andcharacteristics

An alternative to using a phased array to steer a radar beam is to electronically control the orientation of an inertialess broadband microwave reflector. Recent experiments have demonstrated that a planar plasma mirror immersed in a magnetic field can be formed with electron densities high enough to reflect X-band microwave beams. A plasma mirror performs like a metal mirror, but it is inertialess. Compared to high performance phased array systems, a plasma mirror based radar system is much simpler and is therefore more affordable. Electronic steering of microwave beams using a plasma mirror permits the use of wide instantaneous bandwidth waveforms. Potential areas of application for a plasma mirror based antenna system include ship self-defense, high-resolution radar imaging, target identification, electronic countermeasures, high data rate communications, spread spectrum links and remote sensing. As a reflector, the plasma mirror exhibits extremely low loss and the reflectivity is very nearly 100%. Since a perfectly reflecting object cannot radiate, the noise temperature contribution of the plasma mirror to the antenna temperature is likely to be small. The plasma sheet can be steered in elevation by tilting the magnetic field, and steering in azimuth may be accomplished by designating cathode initiation sites. Switching times between successive mirror orientations may be less than 20 μs