Optimum coupling of a Gaussian beam to a corner reflector with a four-wavelength antenna

The coupling of a Gaussian radiation beam to a corner reflector with a four-wavelength long wire antenna was studied theoretically and experimentally. The antenna configuration in conjunction with a Schottky barrier diode is recently used widely as a fast submillimeter wave detector. The optimum angle focusing the radiation to the antenna has been obtained and is 11° (half-width at the 8.7dB points).     

Convergence Analysis of the Block Householder Block Diagonalization Algorithm

This paper develops algebraic and convergence properties of the left and right block reflectors used in the block diagonalization algorithm. Several numerical illustrations are reported.AMS subject classification (2000) 65F20, 15A23.Submitted December 2002. Accepted October 2003. Communicated by Per Christian Hansen.     

Tamm plasmon-polaritons: First experimental observation

We report on the first experimental observation of Tamm plasmon-polaritons (TPP) formed at the interface between a metal and a dielectric Bragg reflector (DBR). Contrary to conventional surface plasmons, TPPs have an in-plane wave vector less than the wave vector of light in vacuum, which allows for their direct optical excitation, and can be formed in both the TE and TM polarizations. The angular resolved reflectivity and transmission spectra of a GaAs/AlAs DBR covered by Au films of various thicknesses show the resonances associated with the TPP at low temperatures and at room temperature. The in-plane dispersion of TTPs is parabolic with an effective mass 4×10⁻⁵$4\times 10^{-5}$ of the free electron mass.     

光电遥感器反射镜组件过盈接触分析

针对空间光学遥感器反射镜组件结构中存在的过盈配合接触非线性问题,利用非线性有限元分析软件ABAQUS进行结构分析。文中围绕反射镜组件结构中接触问题的非线性特征为重点,分析了过盈量、摩擦系数等参数对反射镜的影响。通过非线性有限元模型的建立、分析、验证最终确定该结构的合理过盈量为0.08 mm。有限元分析的结果对于改进空间光学遥感器装调工艺具有非常重要的理论参考依据。     

Monolithic white LED based on Al_xGa_(1-x) N/InyGa_(1-y)N DBR resonant-cavity

A monolithic white light-emitting diode (LED) with blue and yellow light active regions has been designed and studied. With the AlxGa1-xN/InyGa1-yN distributed Bragg reflector (DBR) resonant-cavity, the extraction efficiency and power of the yellow light are enhanced so that high quality white light can be obtained.     

Monolithic white LED based on AlxGa1-x N/InyGa1-yN DBR resonant-cavity

A monolithic white light-emitting diode (LED) with blue and yellow light active regions has been de-signed and studied. With the AlxGa1-xN/InyGa1-yN distributed Bragg reflector (DBR) resonant-cavity, the extraction efficiency and power of the yellow light are enhanced so that high quality white light can be obtained.     

基于极化分解的抗角反射器干扰研究

角反射器干扰是舰船应对反舰导弹的一种重要无源干扰形式,为了提高反舰导弹的作战效能,利用目标宽带条件下极化分解比重邻频差异的统计特性,将Krogager极化分解算法用于舰船和角反射器阵列的鉴别。该算法采用双门限的设定,不仅可以判别待识别模式极化分解在频率上的稳定性,而且可以进一步判别在姿态上的稳定性。结果表明角反射器阵列的极化分解比重不仅随频率变化具有稳定性,并且随角反射器个数的变化也具有稳定性,而舰船的极化分解比重随频率的变化具有敏感性,达到较好的鉴别效果。     

影响反射面天线副瓣性能的机理

由于反射面天线中抛物盒顶部开口所造成结构不连续，使其开口处产生的散射场对抛物盒的反射场干涉而造成口径场畸变，从而导致了天线副瓣性能变差。该文根据天线方向图与其口径场之间的关系，通过理论分析和仿真计算，分析、讨论了口径场分布影响天线副瓣性能的主要机理。     

基于谐振式反射器的脑活动探测天线设计

设计了一款用于脑活动探测的超宽带定向天线。该天线采用了平面菱形单极天线的宽频带特性,通过缺陷地结构实现小型化。为了增强天线的定向辐射能力,设计了一种花瓣形谐振式反射器,在较宽频带内产生同相反射,并可减少剖面高度至0.1λ0。该天线整体结构具有尺寸小、重量轻的特点。对天线结构进行仿真优化并加工实测,测试结果与仿真的一致性表明了该天线具有超宽带的特点,实测阻抗带宽为0.91~2.42 GHz(91%),且远场方向图表明了天线具有良好的定向性能,因而该天线可以应用于人脑活动探测等领域。     

全介质超周期光栅太赫兹波段宽带完美反射器设计

提出一种超周期全介质光栅结构,该类结构在单个周期内具有多个不同宽度亚单元光栅条,基于优化超周期单元结构的占空比、高度以及光栅条宽度等几何参数,实现太赫兹波段(1.2-2.0THz)宽带完美反射特性。利用S-参数反演算法,有效提取亚波长超周期全介质光栅结构的等效参数,包括等效折射率、等效介电常数、等效磁导率以及等效阻抗。分析超周期光栅结构等效参数,结合完美反射条件,证实该类光栅结构的宽带完美反射特性。基于矢量全波计算方法,数值模拟超周期光栅结构的电磁场分布,揭示其宽带太赫兹波完美反射Mie氏谐振特性和电磁耦合特性。