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QIYUE YU RYO TAGUCHI MASAHIRO HOGURO HIDEYOSHI HORIMAI TAIZOU UMEZAKI 《Electronics and Communications in Japan》2016,99(1):3-11
The demand for three‐dimensional (3D) measurement technology has been increasing, but in many of the traditional 3D measurement methods, such as the method using phase shift pattern projection, it is difficult to measure the shape of specular‐reflective and transparent objects, because the power of the light reflected from specular reflective objects is too high and that from transparent objects is too low. Consequently, digital cameras cannot acquire accurate information from reflected light. Digital holography has been used as a means of resolving this problem. In traditional digital holography, the interference fringes of the light from the object being measured and the reference light can be captured by a digital camera. Using the Fresnel diffraction principle, the phase information in the light from the object being measured can be acquired and the shape of the object can be calculated by interferometry. Digital holography can be used to measure reflective and transparent objects. However, by the principle of Fresnel diffraction, dc and conjugate components exist in the calculated phase information a noises, so that the accuracy of measurements is reduced. Phase shift digital holography can remove noise by using special devices to change the phase of the reference light, but the devices are costly and the systems are complex, so that practical application of phase shift digital holography has been difficult. In this paper, we propose a new method of phase shift digital holography using the light detection principle. We also propose a digital holography reconstruction method using the convolution approach rather than the traditional Fresnel approach. The proposed method results in a compact phase shift holography system with lower cost and greater accuracy than the 3D measurement method. Therefore, the practical applications of digital holography can be realized less expensively and more accurately. 相似文献
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天线基本概念和原理实验教学设计与实现 总被引：3，自引：0，他引：3
针对教学中学生在理解天线基本概念和原理方面的困难,本文设计并实现了天线电参数测量实验。实验系统以矢量网络分析仪为基础,在微波暗室中搭建,具备天线方向图、增益和电压驻波比等参数测量功能。本文给出了系统配置和实验流程,并就如何基于天线测量系统开展相关教学工作进行了讨论。实践表明,实验教学是提高天线理论教学效果的有效手段。 相似文献
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天线设计是实现无线无源声表面波扭矩检测的重要环节。针对待测扭矩的转轴结构设计了阅读器的分段环状天线,使用三维电磁仿真软件HFSS仿真了天线的中心频率、带宽、输入阻抗和方向图,在仿真优化的基础上制作了分段环状天线,并进行了相应的测试。测试结果表明,天线中心频率为431.6 MHz、带宽为424～440 MHz、输入阻抗接近50Ω,且天线所在平面具有较好的全向性。包括该阅读器天线的声表面波扭矩检测系统可实现较准确的扭矩测量,在-80～80 N·m时满量程误差为2.5%。 相似文献
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从颜色的三重属性出发,设计生成了测定颜色亮度、色调和色饱和度的三维色域测试图,用这些测试图,对被测显示器进行了色度测试,得到了不同亮度下的三维色域图。用切片算法计算了被测显示器的三维色域,并与笔者之前基于相加混色原理计算的理论三维色域值进行了比较,结果表明二者基本相等。 相似文献
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Jun Yeong Seok Seul Ji Song Jung Ho Yoon Kyung Jean Yoon Tae Hyung Park Dae Eun Kwon Hyungkwang Lim Gun Hwan Kim Doo Seok Jeong Cheol Seong Hwang 《Advanced functional materials》2014,24(34):5316-5339
Issues in the circuitry, integration, and material properties of the two‐dimensional (2D) and three‐dimensional (3D) crossbar array (CBA)‐type resistance switching memories are described. Two important quantitative guidelines for the memory integration are provided with respect to the required numbers of signal wires and sneak current paths. The advantage of 3D CBAs over 2D CBAs (i.e., the decrease in effect memory cell size) can be exploited only under certain limited conditions due to the increased area and layout complexity of the periphery circuits. The sneak current problem can be mitigated by the adoption of different voltage application schemes and various selection devices. These have critical correlations, however, and depend on the involved types of resistance switching memory. The problem is quantitatively dealt with using the generalized equation for the overall resistance of the parasitic current paths. Atomic layer deposition is discussed in detail as the most feasible fabrication process of 3D CBAs because it can provide the device with the necessary conformality and atomic‐level accuracy in thickness control. Other subsidiary issues related to the line resistance, maximum available current, and fabrication technologies are also reviewed. Finally, a summary and outlook on various other applications of 3D CBAs are provided. 相似文献
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根据天线远场测试理论,结合应用实例,分析了微波暗室和斜天线测试场作为天线远场测试场的适应性。对从微波暗室和斜天线测试场得到的双脊喇叭天线远场方向图及相关数据进行了分析,总结出两种天线测试场对天线远场测试影响的特点和规律,并对实际应用提出了指导性建议。 相似文献
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针对5G大范围覆盖的应用场景进行了设计探讨,提出通过对基站天线垂直面进行余割平方成形、以保证大范围覆盖应用场景下信号的均匀性的方法。首先通过算法推导,证明余割平方成形的功率辐射波束可满足5G信号均匀覆盖的要求;其次,采用约束最优化方法,把天线的方向性系数作为目标函数,把指定区域的波束电平作为约束函数,求解基站天线辐射单元的权值,得到满足余割平方成形的辐射方向图。在MATLAB环境下开发了实现此算法的程序。本文的创新之处在于用实际的单元方向图和约束最优化方法,在保证天线增益最优的前提下,综合出需要线阵列天线方向图。引入仰角单元与其他正常单元一起综合方向图,解决顶盲问题,是这个方法的一个应用实例。最后,仿真验证该方法,并设置场景对应用余割平方成形的天线与常规天线的信号覆盖进行比较,证明该方法对信号均匀性有极大的改善。 相似文献
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数字阵列天线测量方法研究 总被引：1，自引：0，他引：1
提出了数字阵列天线应测量的技术指标体系。基于数字阵列天线各通道的幅度相位可控,推导出了数字阵列天线方向图的中场测量公式。在已知数字阵列TR组件接收电路增益的基础上,给出了数字阵列天线接收增益测量方法。为避免分别测量数字阵列天线的有源电压驻波比和发射增益,给出了等效全向辐射功率的测量方法。实验结果验证了数字阵列天线方向图和接收增益测量方法的正确性。 相似文献
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为了节省基站天线所占空间资源,降低其运营成本,现代移动通信需要将多个天线阵列紧密地排列在一起,构成多频共口径基站天线。多天线的紧密排列势必造成天线间强烈的耦合,不仅使得天线阻抗失配、隔离度变差,同时也造成辐射方向图的严重变形。因此,近年来多频共口径基站天线的去耦成为工业界和学术界研究的热点,早期的去耦技术主要是面向改善天线的阻抗匹配和隔离度,而对面向方向图保形的去耦技术研究相对较少。文章在简要介绍面向方向图保形的基站天线去耦技术的研究现状的基础上,重点阐述了褚庆昕教授天线射频团队基于感应电流抵消、耦合场抵消和辐射阻断等原理,提出的几种新型的去耦技术。这些技术不仅可以有效地改善基站天线的阻抗匹配和隔离,更重要的是很好地实现了天线方向图保形。仿真和测试结果验证了原理的正确性和设计的可行性。一些技术已被用于5G基站天线产品。 相似文献
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为了优化超宽带天线的阻抗带宽,提出了一种改进的杠铃形超宽带天线,通过增加阶梯形缺口及采用部分接地面从而改善超宽带阻抗匹配。测量结果表明,天线的输入阻抗带宽达74.7%（3.45~7.56 GHz）,同时数值仿真表明在y-z和x-z平面方向图呈对称分布。 相似文献
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Nobuo Kochi Tadayuki Ito Kazuo Kitamura Shun'ichi Kaneko 《Electronics and Communications in Japan》2013,96(6):9-21
Three‐dimensional measurement and modeling systems with digital cameras on PCs are now making progress and increasingly felt to be desirable in terrestrial (close‐range) photogrammetry for such sectors as cultural heritage preservation, architecture, civil engineering, manufacturing, measurement, etc. Therefore, we have developed a system to improve the accuracy of stereo‐matching, which is the very core of 3D measurement. As a stereo‐matching method, in order to minimize mismatch and to be robust in geometric distortions, occlusion, as well as brightness change, we invented the Coarse‐to‐Fine Strategy Method by integrating OCM (orientation code matching) with LSM (least squares matching). This system could attain an accuracy of 0.26 mm in experiments on a mannequin. In real‐world experiments on archaeological ruins in Greece and Turkey, the accuracy was within 1 cm, compared with their blueprint plan. Formerly, workers required at least 1.5 months for this kind of survey operation with existing methods, but now only 3 or 4 days is needed. This confirmed the practicality and efficiency of the new method. Herein we demonstrate our new system of 3D measurement and stereo‐matching and present some concrete examples of its practical application. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(6): 9–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11459 相似文献
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基于“2+1”相移算法的正交复合光三维测量方法 总被引：3，自引：0，他引：3
提出一种基于"2+1"相移算法的正交复合光栅投影三维测量方法。用2帧相移量相差为π/2的正弦光栅加1帧背景光代替传统正交复合光栅相位测量轮廓术(OCGPMP)中3帧等相移正弦光栅,并将受背景项调制的载波频谱放在受2帧正弦相移光栅调制的载波频谱中间,由于背景项只有直流分量对载波的调制,与相邻调制载波交流调制成分不会发生频谱混叠,从而拓展了两相移光栅的载波频谱宽度,有效减少了频谱混叠,降低了相位测量误差。计算机仿真和实验结果表明,该方法将测量精度提高到传统OCGPMP的1.74倍。 相似文献
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研究了一种应用于卫星通信地面站的新型单臂平面螺旋天线,该天线采用圆柱螺旋激励同轴线馈电,可以形成倾斜的波束,通过改变圆柱螺旋的参数可以调整其输入阻抗以达到阻抗匹配的目的.用矩量法求解了天线的电流分布和三维辐射方向图以及增益轴比等参数,计算结果与参考文献很吻合.为了增强天线的方向性系数和增益,以四元天线阵为例,研究了这种天线组成的天线阵的辐射特性,给出了天线阵的三维辐射方向图.计算结果表明,该天线组成的天线阵同样具有倾斜的波束指向,各天线单元的输入阻抗为接近50 Ω的纯电阻,增益比单个天线单元提高6.3 dB. 相似文献
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低频天线外场测试时往往很难彻底消除地面反射的影响,而地面反射波对直达波的矢量叠加导致待测天线口面上场强分布不均匀,引入较大的测试误差。为消除或减小误差,本文通过建立地面反射模型分析了收发天线高度、收发天线水平距离及地面反射特性对待测天线口面上的反射波或合成场的影响,推导了合成场分布、最佳发射天线高度等计算公式。利用该模型基于实测数据拟合得到地面反射系数幅度和相位,从而得到优化后的测试天线布局。本文基于该模型对外场测试天线高度进行优化后,待测天线口面垂直方向上场强幅度最大值与最小值比值由5.4 dB降到1 dB以内,证明了该分析方法的有效性。该方法可用于低频大口径天线的外场测试方案设计及试验验证工作。
相似文献17.
In this letter, a novel hybrid planar inverted‐F antenna (PIFA) with a T‐shaped slot on the ground plane is proposed. The loop structure formed by the feed line and shorting pin can be operated as a series and shunt inductance for the PIFA and the T‐shaped slot antenna, respectively. The PIFA operates at a frequency of 1.75 GHz, while the T‐shaped slot on the ground plane operates at 2.4 GHz by the same voltage feeding source. The height of the PIFA is 6.5 mm, and the size of an upper patch is designed to be 30 mm…16 mm. The measured relative impedance bandwidth of the PIFA and the T‐shaped slot are about 12% and 21%, respectively. In addition, good antenna performance was achieved. 相似文献
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介绍了用卫星源法测量卫星通信地球站天线的特点。简述了利用3dB和10dB波束宽度确定地球站天线增益的原理和方法。提出了利用外推法确定天线增益频段特性的一种简单方法。对波束宽度法测量增益的误差进行了分析和估算,其均方根误差±0.387dB。最后给出了某工程应用的C波段15m地球站天线增益测量结果,增益测量结果与理论计算结果吻合很好。 相似文献
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本文介绍了所研制的二维微定位柔性系统和一维精密转动系统,进行了相关技术的研究并给出了设计参数,使SPM能够满足高精度下的大尺寸平面样品以及球形被测样品的全范围检测,扩大了扫描探针显微镜（SPM）在超精密工程中的应用范围。 相似文献