涂覆球体的散射矩阵及极化分析

利用物理光学法及平面板块元法，通过场的Ｆｒａｎｚ表达式，对涂覆 散射阵进行了推导和计算，然后通过散射阵分析目标散场场的极化特性参数和最优极化，并给出了具体算体。     

“动中通”接收天线极化匹配及跟踪技术研究

为了稳定"动中通"接收天线的极化轴,克服波束滚动引起的交叉极化干扰,从而提高"动中通"通信质量.以波束实时对准为依据,分析极化匹配的原理,研究"动中通"中交叉极化干扰的产生途径.利用坐标旋转变换导出极化角的计算公式,讨论极化跟踪的必要性,建立极化跟踪的模型.采用电子变极化技术设计了适用于平板天线的"全电子"新型极化跟踪网络,阐述该网络的工作原理,为"动中通"的极化跟踪提供了新的途径.     

高分辨率多极化SAR图像目标分类误差分析

讨论了多极化SAR系统的极化误差及其对多极化SAR图像极化匹配目标分类性能的影响，并给出了计算结果。分析表明，多极化SAR系统的极化通道幅度不平衡误差对目标极化匹配结果的影响最大，交叉极化干扰项对此也有较大的影响。     

特殊散射矩阵和极化特性分析

本文利用散射矩阵和单站雷达系统的最优极化状态分析，提出了共极化匹配系数，交叉极化系数和自适应极化匹配系数三个新概念和便于计算的表达式。对三类特殊形式用射矩阵对应的散射问题进行了极化特性分析，并给出了若干结论     

运动估计误差对同时极化测量影响和分析

同时全极化雷达是面向空中运动目标动态散射矩阵测量的一种全极化雷达，针对同时全极化雷达系统特点，对同时全极化雷达系统中匹配滤波器引入的误差进行了分析，并仿照分时全极化雷达系统模型的发射和接收失真矩阵模型，给出了匹配滤波器引入的失真矩阵及各矩阵元素的物理意义。分析了目标运动估计对目标动态散射矩阵测量的影响机理，提出了运动估计误差矩阵，利用该矩阵对同时全极化雷达测量影响进行了定量仿真分析，从而为同时全极化雷达系统运动估计方法的性能要求提供理论依据。     

基于极化变换的极化匹配滤波器及其通带理论

借助极化基变换思想,通过矩阵特征值与特征矢量的方法求取了部分极化情况下极化匹配滤波器的极化天线最优接收极化方式,即最优极化Jones矢量解。分析了极化白化滤波器与匹配滤波器的性能差异,提出了极化白化-匹配联合滤波方法。针对极化匹配滤波器,分析了其最优极化接收Jones矢量在极化复平面上的表征。并在极化复平面上分析了极化通带的特性,得出在poincaré球上的极化球冠的通带映射到极化复平面变化为极化圆的表征模式,给出了极化圆随通带大小变化的趋势,这是极化通带理论的一个新发展,为极化滤波创造了简便的判决方法,同时为极化滤波中的数据处理提供了新的途径。     

目标RCS的理论值与实测值的关系

指出了目标的理论RCS与其实测RCS的差别，并导出了其关系式；在poincare球上表征了极化匹配因子ρ与目标PCS的理论值σ的大小，便于从几何学直观地了解极化匹配情况与最佳RCS大小。     

单站雷达系统的极化匹配系数

在通讯系统中天线的极化匹配系数这一概念的基础上,根据雷达目标应用中的最优极化状态的分析,提出了单站雷达系统中天线的共极化匹配系数,交叉极化匹配系数和自适应极化匹配系数的新概念,并给出了便于计算的表达式。     

接收线极化卫星节目的天线极化匹配

本文介绍了接收线极化卫星节目时，合理选择接收天线馈源，正确调整天线极化匹配的方法，以有效地抑制反极化干扰，提高接收质量。     

卫星接收中线极化匹配的理论分析与调整方法

本文根据线极化的基本原理和极化角调整的实际，为了便于分析、计算和测量，提出了极化角的新定义和极化偏角，极化源转角的概念；使用解析几何方法，给出了方位角、仰角和极化角在三维空间中的位置；根据位置图，阐述了线极化匹配调整的内容、步骤和极化角的调整方向；详细介绍了极化角预调的方法，给出了极化源转角的实测数值；最后介绍了实际调整经验。     

特殊散射矩阵和极化特性分析

本文利用散射矩阵和单站雷达系统的最优极化状态分析,提出了共极化匹配系数、交叉极化匹配系数和自适应极化匹配系数三个新概念和便于计算的表达式。对三类特殊形式散射矩阵对应的散射问题进行了极化特性分析,并给出了若干结论。     

Polarization control for coherent fiber-optic systems using nematicliquid crystals

One of the obstacles to coherent fiber-optic communications is the unpredictable polarization drift which necessitates the use of an active polarization controlling system to match the polarizations of the signal and local oscillator. The polarization match must be maintained during the reset of any of the finite range components to prevent loss of data. A novel and practical system which uses three liquid-crystal devices for the polarization matching process is presented, and the required reset control algorithm and its derivation are described in detail     

极化滤波器的性能比较

基于极化滤波器的最优解,分析了最优极化滤波器的性能,并与固定极化、干扰抑制滤波器ISPF、信号匹配滤波器SMPF进行了比较.最优滤波器的性能比ISPF和SMPF平均要好1～3dB,比固定极化平均要好6～15 dB,最高可达30 dB以上.因此,最优极化滤波器的得益还是很可观的,这对研究最优极化理论的应用具有重要的理论指导意义和使用价值.     

Specification of polarization parameters for optimal-performance inrain of dual circularly polarized radio links

Rain depolarization of nominally circularly polarized waves alters the polarization state of the wave to produce a polarization ellipse in which the major axis is tilted with respect to the horizontal. Tilt angles for right-hand and left-hand polarization are opposite in sign. It is shown that these tilt angles are almost independent of rain rate and only slightly dependent on frequency. At 62 GHz the magnitude of tilt is close to 60°C. The suggestion is made that the antenna system be deliberately designed to match, as closely as possible, the polarization state of the incoming wave when the expected rain attenuation is at the design maximum (rain margin) for a given communications link. This strategy assures that the crosstalk between polarizations will be minimized when the signal-to-thermal noise ratio (SNR) is at its lowest value. In clear weather, the SNR will be larger, and a greater degree of polarization crosstalk can be tolerated. Finding an optimal match involves selection of the correct rotational orientation of at least one of the antennas as well as specification of its axial ratio to lie between minimum and maximum limits     

Photorefractive polarization couplers in elliptical core fibres

Photorefractive polarization couplers written internally in germanium-doped elliptical core fibers at 488, 514, and 532 nm are reported. Complete power transfer between the orthogonal polarization modes of the fiber was achieved for couplers written at 514 and 488 nm, respectively. It is shown that the couplers are nonuniform in length because of the high photoinduced attenuation and also due to two-photon absorption. Polarization coupling of higher order modes is also demonstrated at shorter wavelengths where their polarization beat lengths match the polarization beat length of the fundamental mode at which the coupler was written.<>     

天线特性测量中极化基失配的影响及校准

对一部待测、待评估的天线,其交叉极化特性实际上是依赖于极化基的,极化基匹配或失配情况下,得到的交叉极化性能评估结果也不一样.文中首先建立了天线极化特性测最模型,推导了交叉极化测量校准约束模型,给出了该约束下的最佳收发极化基.并针对实际的雷达天线进行了外场测量实验,实测处理结果验证了上述结论.利用约束模型可对实测的极化方向图实现有效的校准.     

Study of form birefringence in waveguide devices using the semivectorial beam propagation method

Waveguide devices based on nonbirefringent substrates may still have form birefringence if index discontinuities exist. It is demonstrated that the semivectorial beam propagation method can be used to study the polarization dependence in waveguide devices. It is shown that the calculated coupling lengths of planar directional couplers match within 3.5% of analytical solutions. Results on polarization dependencies of coupling lengths and bending losses of rib waveguide devices are presented. Results of rib waveguide directional couplers indicate that the form birefringence can be significant. Losses of S-shaped bends are weakly polarization dependent in the low-loss regime.<>     

多径循环平稳信号二维波达方向估计极化域平滑法

针对相干循环平稳信号,该文提出一种估计二维波达方向的新方法极化域平滑法。该算法充分利用信号的循环平稳特性以及极化多样性,在不影响阵列孔径的情况下,进一步增大可估计的相干信源数目,且具有信号选择和噪声抑制能力。估计过程中各参数自动配对。仿真结果验证该文方法的有效性。     

Coplanar-waveguide-fed slot-coupled rectangular dielectric resonator antenna

A novel coupling scheme to a rectangular dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved through a narrow slot at the end of a coplanar waveguide (CPW). The objectives of this design are to maximize the coupling, match the dielectric resonator to the CPW feed line, achieve resonance at the desired frequency, obtain linear polarization with low cross polarization components, and minimize back radiation without using a back conductor. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results.