一种窄带SIR带阻滤波器的设计

介绍了嵌入式并联λ8/4(λ8为波长)的开路支节的基本结构与特性.采用带状线,设计了一款中心频率为2.46 GHz、阻带宽度50 MHz、最大阻带衰减为60 dB的三阶嵌入式并联开路支节窄带带阻滤波器.与传统的并联开路支节带阻滤波器相比,嵌入式并联开路支节带阻滤波器的横向尺寸减小,结构紧凑.采用阶梯阻抗谐振器(SIR)结构,按相同指标设计了一款三阶嵌入式SIR窄带带阻滤波器.与嵌入式并联开路支节带阻滤波器相比,嵌入式SIR带阻滤波器结构更为紧凑,纵向尺寸缩小约17.5％,并具有更好的谐波抑制特性.     

相控参量阵波束合成设计

针对矩形和圆环形换能器阵列,完成了宽带参量阵信号的波束合成仿真与结果比较分析.仿真结果表明,同等阵元个数N=9、相似阵列边界半径rm=49 mm条件下,矩形阵列差频波波束主瓣-3 dB指向角约为6.3°(圆环阵列约为7.4°),旁瓣几乎被完全抑制(圆环阵列约为主瓣峰值的10％),矩形阵列更利于提高主瓣指向性和抑制旁瓣幅度.针对矩形阵列,该文仿真分析了采用阵元信号延时方法实现参量阵信号波束偏转时的各波束特征,仿真结果显示,偏转后波束存在主瓣峰值点幅值削弱、主瓣峰值点未对准预定方向、主瓣宽度增大等问题.分析表明,以上问题可通过增加阵元数目及增大阵列尺寸进行修正.     

Third-order voltage-mode active-C band pass filter

In this research article, a new third-order voltage-mode active-C asymmetrical band pass filter is proposed. It uses three numbers of current-controlled current conveyors and three numbers of equal-valued capacitors. The topology has the following important features: uses only three active elements, uses three capacitors, uses all grounded capacitors and no resistor is suitable for integrated circuit design, there is no matching constraint, high input impedance, low output impedance, central frequency can easily be electronically controlled by bias current, and frequency response is asymmetrical in nature. The application of the proposed topology in the realisation of a voltage-mode sixth-order symmetrical band pass filter has been demonstrated. The workability of the proposed topology and sixth-order filter has been confirmed by simulation results using 0.35-µm Austria Micro Systems complementary metal oxide semiconductor technology.     

WRC-15前俄罗斯L频段航空移动台站申报引发的思考

本文通过分析WRC-15前夕俄罗斯向国际电联申报L频段航空移动台站台站的情况,详细论述了其对我国此频段内其他各业务的影响,说明了我国在L频段国际台站申报的重要意义。     

Bipolar transport materials for electroluminescence applications

Benzofuranyl benzene incorporating naphthyl (phenothiazinyl or dimesitylboryl) entities via meta-conjugation have been synthesized. These compounds exhibit bipolar transport characteristic with mobilities in the range of 10⁻⁵ to 10⁻⁴ cm²/V s at an electric field of 4 × 10⁵ V/cm. The compounds with two naphthyl or dimesitylboryl substituents emit in the violet region with good solution quantum yields. The OLEDs fabricated from the benzofuranyl/dimethylboryl, benzofuranyl/naphthyl and benzofuranyl/dimethylboryl/phenathiazine derivatives have maximum external efficiencies of 1.01%, 1.41% and 3.14%, respectively.     

半导体器件非抛物型流体动力学模型

从 Boltzmann迁移方程出发 ,在载流子分布函数没有任何限制 ,能带结构也没有任何假设的情况下导出了 Boltzmann迁移方程的前三阶矩方程 ,然后在 Kane弥散关系和指数定律弥散关系两种非抛物型能带关系下分别得到了非抛物型流体动力学模型 ,并对模型作了归一化处理。     

快速轨道交通无线通信频段的选择和频率配置

探讨了城市快速轨道交通中无线通信频段的选择及频率配置问题,介绍了一种用无线电频率管理程序提高频率利用率的方法。     

A multi‐access method for BPL based on orthogonal pulse division multiplexing,barker‐code‐based spectrum spreading and orthogonal frequency division multiplexing

A highly efficient multi‐access scheme of broadband power line (BPL) communication, named as OFDM‐BPS‐OPDMA, is proposed based on the Orthogonal Pulse Division Multiplexing Access (OPDMA), Barker‐code‐based Spectrum Spreading (BSS) and Orthogonal Frequency Division Multiplexing (OFDM) method. The orthogonal pulses are generated by using the eigenvectors of Hermitian matrix. At the same time, a specific pulse will be allocated to every user of the communication system. The transmitting data are first modulated by OFDM. Then, it is processed with OPDMA and BSS. Finally, the data is sent to the power line channel. On the receiving side, the data is processed with BSS demodulation, OPDMA demodulation and OFDM demodulation, and the receiving data for each user is acquired. Because of the orthogonality between these pulses, the multi‐user interference could be eliminated; when BSS is used, the waveform restoration is enhanced. Meanwhile, with the help of OFDM, the multi‐path interference is mitigated. Particularly, all users can share the resources of time and spectrum without interfering with others, and get excellent reliability in the concerned scheme. When OFDM is used, the sub‐carriers may be allocated dynamically, and the legal radio frequency band could be shunned by sharing the common bandwidth with other communication systems. Copyright © 2009 John Wiley & Sons, Ltd.     

硅树脂调制的可调光子晶体

文章提出一种利用硅树脂调节光子晶体光子带隙的方法,光子晶体波导是通过往二维正方形光子晶体的介质柱之间填充硅树脂得到的,利用温度场改变硅树脂的折射率.数值模拟结果表明:通过温度场可对这种光子晶体的禁带结构进行调节.这种可调光子晶体可应用于制作新颖的偏光片和光开关.