共查询到20条相似文献,搜索用时 375 毫秒
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设计了一副改进的非对称平衡对拓Vivaldi天线。辐射贴片外边缘用3阶多项式曲线修正,以实现很宽的阻抗带宽。在天线口径处嵌入一个金属贴片作引向器以改善天线的辐射特性。对辐射贴片引入非对称性,使得E面波束偏离得到进一步补偿。实测结果表明,该天线具有极宽的工作带宽,在2~40 GHz内的增益大于0 dBi,且在15~30 GHz内的增益大于14 dBi;E面的波束偏离在6~40 GHz频率范围内小于3°。该天线具有结构简单、尺寸紧凑(44 mm×98 mm)以及方向图稳定等优点。该天线能够较好地应用于相控阵、超宽带系统等。 相似文献
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通过对微带贴片天线单元的仿真与优化,得出了法向轴比小于3 dB的右旋圆极化微带贴片天线单元;用所得的天线单元组阵得到9元相控阵天线,仿真得到其S11参数小于-16 dB、增益大于13 dB和轴比小于3 dB.针对微带贴片相控阵天线的轴比特性,提出了降低轴比的几种布阵方法,得到0.2 dB的轴比,最后分析并总结了改善微带贴片相控阵天线轴比的一般方法. 相似文献
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宽带相控阵天线一般利用时延补偿技术来实现.首先分析了波束指向的偏移对相控阵天线带宽的限制.接着对子阵均匀划分、不均匀划分、部分相位加权等方法进行了全面分析和阐述.相位的确定是通过遗传算法实现的.证明了采用这些方法,阵列的栅瓣、波束指向偏移都有较大抑制,带宽相应增加,为宽带相控阵天线的设计提供了参考价值. 相似文献
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介绍了一种用于共形相控阵天线的宽频带宽波束双圆极化微带贴片天线,并利用Ansoft公司的电磁场高频结构仿真软件HFSS对所设计的天线进行计算分析。所设计的微带贴片天线在设计频段内反射损耗小于-20 dB,半功率波束宽度大于±60°。 相似文献
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采用双层矩形贴片加切角的结构设计圆极化单元,并将其组成应用于X 波段64 单元高增益圆极化微带阵列天线。天线基板采用Taconic-TRF,介电常数4. 5,厚度0. 81mm,损耗角正切0. 0035。利用Ansoft HF-SS 软件对单元及阵列模型进行仿真优化。通过实际测试,64 单元阵列天线轴比AR<6dB 的带宽500MHz,增益达到21. 2dB,S11 <-10dB 的相对阻抗带宽达到6. 9%,天线具有良好的圆极化和阻抗匹配特性。圆极化天线具有较强的抗干扰能力,可很好地应用于电子侦察、电子对抗等领域。设计的圆极化微带阵列天线为组成更大阵列的天线以及构建相控阵天线提供了单元基础。 相似文献
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Michael Reilly 《半导体技术》2004,29(12)
DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system. 相似文献
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Thomas M.Trexler 《半导体技术》2004,29(5)
From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test. 相似文献
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The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high. 相似文献
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The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation. 相似文献
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Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible. 相似文献
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Qi-jiang Ran Pei-de Han Yu-jun Quan Li-peng Gao Fan-ping Zeng Chun-hua Zhao 《光电子快报》2008,4(4):239-242
This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel's. 相似文献
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Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers
A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it. 相似文献
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It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory. 相似文献
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A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working. 相似文献
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《中国通信》2014,(7)
正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks 相似文献