结构紧凑型宽带低副瓣阵列天线

为了满足系统对阵列天线宽带、低副瓣的要求,设计了一款工作在X和Ku波段的结构紧凑型宽带低副瓣阵列天线,相对带宽为54.5%,副瓣电平在-30 dB以下,天线纵向尺寸为4.5λg。阵列天线采用带状线加权馈电网络和宽带带状线偶极子天线一体化设计,偶极子天线用短路探针对馈电分布电容进行补偿并加载寄生贴片,有效展宽了带宽;馈电网络通过拓扑结构设计获得各功分节点最佳功率比值,对各功分节点位置合理布局缩减馈电网络纵向尺寸。在微波暗室利用近场测试系统对阵列天线实物进行测试,验证了仿真结果。     

一种新型高增益小型化四臂螺旋天线

针对卫星通信、卫星导航设备中四臂螺旋天线低仰角增益低、馈电网络尺寸不能满足安装要求的问题,设计了一种新型四臂螺旋天线,采用折叠式威尔金森(Wilkinson)移相馈电网络馈电,采用类八臂渐变式螺旋臂的方法提升天线低仰角增益。天线仿真和测试结果吻合良好,结果显示,在±60°~±90°低仰角范围内天线增益提高了1~2 dB,天线轴比保持在2以内,馈电网络高度降低了1.5 cm。该四臂螺旋天线具有低仰角高增益、圆极化特性良好、尺寸小等特点。     

双角串馈毫米波高增益微带阵列天线的研究

随着现代通信技术和雷达、引信系统的快速发展,对毫米波天线性能要求越来越高,传统的串并联馈电网络已难以满足需求。文中采用双角串馈结构进行馈电,设计并测试了工作在24 GHz 和35 GHz 的两款双角馈毫米波天线。仿真的24 GHz 天线尺寸24.76 mm×16.92 mm,增益15.59 dB,带宽0.4 GHz,仿真的35GHz 天线尺寸17.06 mm×11.22 mm,增益14.73 dB,带宽1 GHz;对35 GHz 天线进行加工实测,实测天线增益为14.2 dB,带宽为1 GHz。分析了天线的主要参数影响以及此种结构天线的极化特性。相对于传统的串并联馈电天线,文中研究的天线具有特殊阵列结构,仅通过角馈线相连,无需馈网,降低了馈电损耗,整体尺寸小,增益高,具有一定的推广意义。     

一种毫米波宽角扫描Vivaldi 天线设计

设计了一种工作于毫米波段的金属Vivaldi 天线,天线宽带扫描性能优异。天线结构利用Vivaldi 作为辐射单元,将其集成到带状线耦合的馈电基板上,馈电网络与辐射天线结构相对独立,便于加工。通过仿真得到:在27. 2 GHz ~46. 0 GHz 范围内VSWR<2;在27. 5 GHz ~42. 2 GHz 频段内,天线驻波比在E 面和H 面45毅扫描范围内满足小于2 的匹配特性。文中利用设置周期性边界条件的方法优化天线尺寸并仿真分析天线参数对扫描带宽的影响。通过驻波比、交叉极化、天线增益的仿真分析天线性能。     

新型左手传输线馈电微带阵列天线

提出了一种采用复合左右手传输线馈电的新型微带阵列天线.该天线利用左手传输线的相位超前特性来补偿传统的右手传输线所具有的相位滞后,从而保证了天线单元之间的同相位馈电,避免了因相位延迟导致的天线波束偏移,并进一步提高了天线的增益.仿真与实际测试证明:与同类型天线相比,该天线具有尺寸小、频带宽和馈电网络设计简单等优点,可在微波系统中实际使用.     

双频双极化微带共形天线

设计了一款工作在不同频率的双极化微带共形天线。首先,天线单元采用矩形微带贴片,并且通过改变贴片尺寸实现两种谐振频率;其次,改变两种单元的馈电方向,以此实现不同极化辐射;最后根据天线单元排布形式,设计了基于T 型功分器的馈电网络。根据最终的仿真结果,加工了天线实验样机。在工作带宽内,天线1、2 不圆度为分别为3. 56dB 和3. 98dB,增益分别为1.1dBi 和0.85dBi。通过比对,实测结果与仿真结果一致性较好,达到了预期目标。     

一种具有高隔离度的双频双圆极化卫星通信天线

 提出了一种新型的用于卫星通信的双频双圆极化多层微带贴片天线.该天线采用兰格耦合器正交馈电,分别在420±1.5MHz和450MHz±1.5MH的收发频率实现右旋和左旋圆极化辐射,且满足单一天线收发双工的通信要求;采用耦合贴片馈电方式和附加集总电路滤波网络,有效地改善了两端口之间的收发隔离度.此外,该天线采用高介电常数的介质基板减小了天线尺寸.兰格耦合器采用曲折线技术减小了馈电网络的结构尺寸(约74.6%).仿真和实测结果吻合良好,在工作频带内收发隔离度大于40dB,VSWR小于2.0,增益大于3dBc,0dB增益宽度及3dB轴比宽度均达到80°.     

可贴敷于人体的RFID 标签天线设计

设计了一款可贴敷于人体的超高频(UHF)射频识别(RFID)标签天线,该天线由矩形辐射单元、环形 馈电和匹配网络组成,其总体尺寸为54. 3 mm×40 mm×0. 8 mm。分析了人体不同部位、天线与人体间距以及天线自 身结构变化对天线辐射性能的影响。通过调节环形馈电和匹配网络尺寸可以实现天线与芯片之间的阻抗共轭匹 配。样品测试结果与仿真结果比较吻合,当标签天线贴敷在人体背部时,实际测量的最大读取距离可达4. 9 m。     

具有紧凑馈电网络的宽带四臂螺旋天线

传统的自相移馈电四臂螺旋天线(QHA)由于最小回波损耗频点和最小轴比频点不在一个频率上,因此,难以在较宽的频带内同时满足良好的阻抗匹配和圆极化特性.虽然采用功分相移网络馈电可以解决上述问题,但是馈电网络尺寸普遍较大,难以应用于手持机上.本文提出了一种底部带有紧凑的功分相移馈电网络的四臂螺旋天线,可以在宽频带内实现四个输出端功率平衡输出,相位两两相差90度.所提出的馈电网络使得四臂螺旋天线既可以实现宽带圆极化辐射,又具有小尺寸,非常适合GPS、北斗移动手持设备的应用需求.     

宽带圆极化锥形辐射单元阵列天线的设计

基于L型探针馈电提出了一种宽带圆极化锥形辐射单元天线的设计方法.为了提高轴比带宽,馈电网络应用带L型馈电探针的宽带90°电桥,锥台单元取代普通平面贴片作为辐射单元.4个单元组阵后可得到的峰值增益为12.7 dB.馈电网络在介质基板的底面以此来减小天线总体尺寸.测量结果与仿真结果吻合良好,天线可实现40.1%(VSWR<...     

A slotted MAC protocol for efficient bandwidth utilization in WDM metropolitan access ring networks

The paper proposes an original wavelength-division multiplexing slotted-ring network architecture with nodes that use one fixed transmitter and fixed receivers. It is shown, through theoretical predictions and simulation results, how a simple slotted medium access control protocol can be implemented to achieve fairness between access nodes and efficient bandwidth utilization when used in a metropolitan access network. Performance for both source and destination stripping schemes has been analytically derived and simulated with a realistic self-similar traffic model. A modified node architecture using a tunable receiver has also been considered and the impact of receiver collisions has been evaluated and analyzed. Finally, the effect of using unbalanced traffic sources has also been analyzed and simulated.     

The system modelling and circuit implementation from time–frequency domain signal specifications

The system modelling and the circuit implementation of the nonlinear circuits using the wavelet domain techniques has been accomplished in this study. When the time–frequency domain specifications have been given as the wavelet ridges, the signal with the given ridges has been synthesized. Then, the dynamical wavelet network has been trained for the synthesized signal. The circuit of the wavelet network has been designed and simulated.     

Extraction of noise current signatures using wavelets in packaged digital systems

This paper discusses a measurement-based approach for estimating the switching noise current waveform in a functioning computer system. The proposed method consists of a wavelet-based approach for denoising the measured waveform and a technique for capturing the result in an accurate and compact model. The method has been tested on simulated and measured data. The test case considered is a high-speed functioning workstation from Sun Microsystems. Using the current source developed, simultaneous switching noise in the power distribution network of the test system has been simulated with good accuracy     

毫米波微带键合金丝互连模型的研究

本文应用神经网络方法、采用FDTD全波分析结果作为训练样本得到了毫米波微带键合金丝互连的参数模型.这个神经网络模型可以指导毫米波集成电路的设计,利用该模型可以得到不同拱高、微带间隙和频率时的电路散射参数.实验测试了键合金丝互连的散射参量并与神经网络模型的结果进行了比较分析.     

多层微带功分网络的设计

介绍一种多层微带功分网络的具体实现过程。利用ADS和HFSS等电磁仿真软件进行了仿真计算,设计出实际的器件。测试结果验证了设计方法的正确性和可行性。该功分网络已经用于雷达系统中。     

大容量广电网的P圈启发式算法研究

结合广电网大容量的发展要求,考虑较为复杂的网状网结构,网络生存性问题日益凸显。对经典的预置圈(P圈)容量算法进行了改进,并选用COST239网络拓扑对改进算法进行编程仿真。结果证明,改进算法在减少预置圈数量的同时能够提高资源利用率,性能有所提高,可以较好地解决广电网的生存性问题。     

Design and performance evaluation of a packet voice system

A packet voice network has been designed using adaptive delta modulators. Tests were performed to examine the effects of packet length and packet loss rate on digital voice intelligibility. The packet voice network was simulated using a SLAM network model to find queue size requirements as a function of packet size, delay distribution, and expiring time out. The queuing strategy is investigated in order to minimize total information loss during channel acquisition delays.     

Power Consumption Based Simulation Model for Mobile Ad-hoc Network

Mobile ad-hoc network has limited battery power. Power consumption control is the main issue in mobile ad-hoc network. Node battery power is a precious resource that should be used in order to avoid the early termination of nodes. Energy management model and power consumption control flow chart is proposed to control power consumption by reducing data transmit time in mobile ad-hoc network. Simulation model has been used to analysis the energy consumption of a node. This has been achieved by estimating the time spent in transmission of data by node. The proposed model has been simulated using OMNET \(++\) simulator. Simulation results show significant energy savings after applying the proposed model and flow chart.     

基于径向基函数神经网络的模拟/混合电路故障诊断

径向基函数神经网络是一种前馈型神经网络,具有较强的函数逼近能力和分类能力,学习速度快等优点.本文采用幅值恒定的正弦信号源进行模拟电路的故障仿真,从频域提取输出信号波形的特征值建立故障字典,应用径向基函数神经网络的这些优点进行响应分析和故障诊断,能够实现快速故障诊断及定位,具有准确率高的特点.     

新型C频段TE21模圆极化合成网络设计

指出了波导结构及微带形式的TE21模圆极化合成网络的不足,介绍了3 dB分支定向耦舍器的基本原理,设计了新型C频段空气带状线形式的圆极化合成网络,并对该结构进行仿真和测试,结果满足性能要求.此种合成网络可与耦合器设计为一体,既可以增加结构强度,还缩短了传输路径,降低了损耗,目前已经成功应用在多种型号天线系统上.