塔康相控阵天线相位校准算法

由于天线要形成旋转的9瓣心脏形方向图,工作中必须对控制天线辐射信号的移相器相位进行实时控制,而移相器的初始相位决定了天线方向图形成的准确性,因此塔康相控阵天线必须进行相位校准后才能正常工作.在对塔康相控阵天线方向图形成原理和天线相位校准方法进行分析的基础上,运用傅里叶变换理论和矢量叠加原理,提出了一种基于矢量叠加的相位校准算法.通过该算法可减少运算量,在保证相位校准精度的前提下,提高了相位校准速度,降低了对硬件平台的要求.实验表明:该算法合理有效、相位校准速度快、相位计算精度高,在塔康相控阵天线中得到了成功应用.     

某型微波着陆设备移相器故障诊断方法研究

针对某型微波着陆设备测试性校准时间较长,影响移相器故障诊断效率的问题,基于相控阵天线相位校准原理,通过对扫描天线阵列参数获取方法以及移相器故障诊断流程的分析,采用相位控制赋形算法计算出了扫描天线固定指向时各阵元支路的最优相移值。由于相位控制赋型算法通过测量辐射功率来调整闭合等式的权值,并且在进行每次相位寻优时都将前一次量化引入的误差计算其中,因此经过少量迭代就可得到移相器的阵列参数,缩短了测试性校准时间,进而用测试性校准所得的阵列参数与工作性校准后存入天线控制器RAM中的阵列参数相比较,快速对移相器进行故障诊断。最后通过仿真验证了该方法的可行性。     

半集总参数定向耦合器及其应用

本文介绍一种27MHz半集总参数定向耦合器的研制结果及其应用情况。在很宽的频率范围内,这种定向耦合器的最大特点是体积小、结构简单、方向性好于30 dB,耦合度可以根据需要进行选择。利用这种定向耦合器做成的电调移相器、相移变化很小的电调衰减器、脉冲调制器、相位调制器和鉴相器等都取得了令人满意的结果。     

RFID标签天线的研究与设计

在RFID技术的发展过程中,标签天线设计已经逐渐成为新的研究热点。论文研究了RFID标签天线领域的关键技术,分析了RFID系统的组成和基本原理．设计并仿真了工作在915MHz的标签天线。论文根据标签天线的基本理论,设计出了一款用于标签的平面单极天线,天线呈S形弯曲,外围尺寸36mm×100mm,该天线的中心频率为915MHz,VSWR〈2的带宽为902MHz-928MHz,方向性比较好。     

悬置带状线T接头等效电路的提取

为了精确地设计移相器,基于带状线的物理结构和传输线模型,分别设计了单片耦合悬置带状线T接头和双片耦合U型悬置带状线T接头的等效电路,然后根据这些电路计算出T接头S参数的幅度和相位,并与Ansoft HFSS软件的仿真结果和实测结果进行比较,验证了文中所提出等效电路的有效性,为电调天线移相器的设计提供了准确模型.     

一款适用于CNSS及GNSS的双频圆极化天线

介绍了一款适用于北斗导航卫星系统（CNSS）以及格罗纳斯导航卫星系统（GNSS）的天线．该天线为双频圆极化层叠贴片天线,可覆盖1258．52～1278．52MHz（133频段）以及1575～1609MHz（B1—2／L1频段）．仿真结果显示,在B3频段和B1—2／L1频段,该天线为右旋圆极化（RHCP）,法线方向轴比均小于1．5,增益可分别达4．6dB和4．7dB,驻波比分别小于1．4和1．1．     

单通道干涉仪测向系统中的高精度数字移相技术研究

为解决单通道干涉仪测向系统中传统数字移相器对参考天线输出信号移相时移相精度不高的问题,基于直接数字频率合成技术(DDS)和混频技术,提出了一种新的数字移相技术。该技术采用两级混频结构,分别进行下变频和上变频。两级混频器的本振信号均由DDS信号发生器产生,通过调节本振信号的相位差,实现对一定频率范围内的输入信号进行0°～360°相位偏移。采用FPGA评估板、DAC FMC子卡、混频器、滤波器等模块制作了输入频率范围为432～434 MHz的移相器样机,对该方法进行了验证,实现了输入信号的0°～360°移相,移相步进小于0.09°,实测误差的均方根(RMS)小于0.8°。     

超短波宽带天线设计与分析

提出了一种新型“V”型天线,并运用实频匹配技术使该天线在25MHz-85MHz获得了优秀的天线性能。该天线在频段范围内VSWR<3,增益主要分布在0-2dB之间,最小增益不低于-6dB,天线效率大于75%,可广泛运用于军事、遥感、环境监测等领域。     

一种80MHz移相器的设计方法

本文介绍了一种中频模拟移相器,该移相器工作频率为80MHz,带宽10MHz,移相度数可达246°,移相线性度较好,最大插入损耗1.85dB,幅度变化小于0.6dB。     

基于简单复合左右手结构的宽带90°移相器

利用简单复合左右手结构的非线性相位特性,提出了一种平面、低插入损耗的宽带90°差分移相器的设计方法。该设计方法的原理主要是通过调节简单复合左右手结构的参数和进行相位比较的传统微带线长度,使二者的相位曲线最大程度具有相同的斜率,并且满足90°的相位差。移相器的幅度和相位测试结果表明:在2.9～8.4 GHz的频率范围内,反射系数小于-10 dB,插入损耗小于0.7 dB,相位不平衡度小于±5°,相对带宽达到了97.3％,而满足相同指标的传统微带差分移相器,其相对带宽仅有11％。该结构设计简单,便于加工。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that