Computation of the resonant frequency of electrically thin and thick rectangular microstrip antennas with the use of fuzzy inference systems

A new method for calculating the resonant frequency of electrically thin and thick rectangular microstrip antennas, based on the fuzzy inference systems, is presented. The optimum design parameters of the fuzzy inference systems are determined by using the classical, modified, and improved tabu search algorithms. The calculated resonant frequency results are in very good agreement with the experimental results reported elsewhere. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 108–119, 2000.     

Modal analysis of probe‐fed circular sector microstrip antenna with and without variable air gap: Investigation with modified cavity model

Determination of accurate modal fields is one of the most crucial issues to understand the proper behavior of circular sector microstrip antennas (CSMAs) to achieve the best performance. In this article, dominant and higher order modal characteristics have been rigorously studied which germinate an improved, accurate, and efficient computer‐aided design (CAD) formulation to estimate the resonant frequency of CSMA with and without air gap between substrate and ground plane. The proposed formulation can address the wide variety of issues (such as substrate height, substrate permittivity, air gap height, higher order modes, etc.). The computed results were validated against the results obtained from high ‐ frequency structure simulator (HFSS) and our own experiments, while they have been also justified through the results obtained from the available literature.     

石英晶体谐振频率测量系统

在石英晶振的生产过程中,切割后的晶振片需要对其共振频率进行快速测量,并通过机械手按频率分选。本文介绍了一种结合单片机、直接数字频率合成器(DDS)和增益鉴相器的简单石英晶振共振频率检测系统,利用晶振阻抗随激励信号频率而变化的特性,在100ms内测得其共振频率,控制成本的同时保证了一定的测量精度。     

基于反推的电液比例系统共振频率控制

针对电液比例系统的非线性以及不确定性因素对破碎频率控制的影响,设计反推的频率控制方法.建立电液比例阀控液压马达的破碎机构的非线性模型,特别是考虑了比例阀的动态频率和阻尼特性,将系统的各不确定性参数对破碎频率的影响等效为液压马达轴上的负载波动;设计基于反推的控制律,构建各步骤的误差信号、虚拟控制信号和目标函数间的关系,在不确定性有界的前提下保证了液压马达输出转速渐近跟踪的稳定性.给出频率控制系统的模型参数,并在基于Matlab6.5的环境下进行了仿真研究以及车载试验,结果表明,对于具有不确定性因素的电液比例频率控制系统,反推控制策略具有较好的控制性能,能够满足共振式破碎机的工程应用要求.     

硅基微带天线损耗机理分析

硅基微带天线存在损耗大、效率低、增益不足等问题。其成因在于以下五种损耗:1.金属贴片及匹配微带线的导体损耗。2.介质的介电损耗。3.表面波损耗。4.半导体基底的电阻性损耗。5.由基底与绝缘层交界面上的载流子运动导致的界面损耗。在深入分析各种损耗的形成机理的基础上,研究了相应损耗的计算模型及其在总损耗中所占的地位,并提出了降低损耗的有效途径。实验结果显示,采用微机械(MEMS)工艺,在高阻硅与低介电常数介质的混合衬底上,生长一层多晶硅薄膜的方法,可有效降低损耗,使硅基微带天线单元的效率达到87%,增益达到8dB。     

小型化多频带微带天线的设计

第三代移动通信对天线的小型化和多频带提出了越来越高的要求,提出了一种双U型槽和弧形边联合加载的平面倒L天线,采用微带馈电;从蜂窝移动通信、全球定位系统和蓝牙通讯对天线的要求出发,设计了两个四频天线:一个覆盖GSM/DCS/PCS/ISM频段,另一个覆盖GSM/GPS/PCS/ISM频段;应用ANSOFT公司的HFSS10.0三维仿真软件,对天线进行设计和优化,最终得到了两个基本符合频段带宽及方向图要求的四频天线,这对微带天线的小型化和多频带技术具有一定的指导意义。     

C波段微带阵列天线的设计分析

微带阵列天线的使用对飞机的隐身性能、机动性能等都具有非常重要的现实意义,在分析矩形微带天线设计原理的基础上,依据指标设计要求,完成了一个C频段微带天线阵的设计;同时,利用三维电磁场仿真软件(Ansoft HFSS)进行了仿真,并对其设计的参数进行了优化;在此基础上,通过实物加工,暗室实测,以及与AnsoftHFSS仿真结果进行比较,达到了C频段微带天线阵设计的目的,具有一定的实用工程价值.     

Computation of resonant frequency for equilateral triangular microstrip antennas using the adaptive neuro-fuzzy inference system

A new method based on the adaptive neuro-fuzzy inference system (ANFIS) for calculating the resonant frequency of the equilateral triangular microstrip patch antenna is presented. The ANFIS has the advantages of the expert knowledge of the fuzzy inference system and the learning capability of neural networks. A hybrid-learning algorithm, which combines the least-square method and the backpropagation algorithm, is used to identify the parameters of ANFIS. The results of the new method show better agreement with the experimental results, as compared to the results of previous methods available in the literature. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 134–143, 2004.     

MEMS层叠式毫米波天线设计

为了提高天线带宽,改善天线性能,提出并设计了一种基于微机械工艺的层叠式口径耦合毫米波天线,该天线中心频点为35 GHz,利用有限宽地共面波导-微带(FGCPW-MS)进行馈电.分析天线结构中的几个关键参数对天线带宽性能的影响,利用HFSS三维电磁场仿真软件进行天线模型仿真.结果表明,该天线带宽为11.8%,增益为7.8 dB,天线辐射效率为71%.与传统微带天线相比,该天线在带宽、增益等方面均到改善,且易与其他有源元件进一步集成.     

单层超宽带微带贴片天线的设计与分析

该文提出了一种新颖超宽带微带天线。该天线由微带宽槽天线的基本结构变形而来,其结构由矩形馈电微带贴片与矩形宽槽孔贴片组成。矩形宽槽孔开在金属GND板上,而矩形馈电贴片在介质板的另一面并在矩形宽槽孔框内偏下方。贴片与馈电线对接处采用渐变结构来达到阻抗匹配。以矩形宽槽尺寸为主构成了低频段的等效谐振电长度,而馈电贴片尺寸构成了高频段的等效谐振电长度。在各自的谐振频区上,矩形宽槽与馈电微带贴片两者相互耦合,构成两谐振电长度的天线叠合组成为一共面天线,从而拓展了天线的带宽。该文运用HFSS仿真软件,根据设定尺寸进行了仿真设计,制备了两只不同频段的样品天线。仿真结果和实验结果基本一致,表明该原理设计出的天线可实现超宽带特性。     

基于有限元法串馈微带天线阵的设计与优化

研究毫米波段串馈微带天线阵的优化问题,阵列采用1/4阻抗变换器的幅度加权方法实现低副瓣。针对阻抗变换段与传输线之间存在不连续导致各单元相位的差异而影响副瓣电平进一步的降低,应用有限元法优化传输线的长度进行相位补偿,使各单元辐射同相谐振。仿真结果表明,优化后的方向图副瓣≤-22dB,较优化前降低了7dB,增益15.8dB,波束宽度9.6°,实现了微带阵列天线的低副瓣、高增益、窄波束的指标要求。     

用于石英晶体——频率测试相位检测技术研究

在使用π网络零相位法对高频石英晶体进行测试时,相位检测技术是关键.本文所设计的鉴相系统采用混频技术,降低所要鉴相的频率,对固定频率进行相位检测.经实验验证,本测试系统的测试频率范围1MHz～200MHz,相位检测的精度能够满足串联谐振频率的测试精度±2ppm的要求,重复精度大于0.5ppm.     

Bacterial foraging optimization technique to calculate resonant frequency of rectangular microstrip antenna

Resonant frequency of rectangular microstrip antenna having various substrate thicknesses are generally calculated using the standard expressions presented in literatures. But these equations suffer from errors when compared with the experimental values due to Quasi‐TEM propagation in the microstrip structure and fringing field. A number of researchers used soft computing approach such as neural networks and genetic algorithm on those equations to minimize the error for better accuracy. Bacterial foraging, an evolutionary optimization technique conceived in recent times, has many advantages over genetic algorithm and is yet to be applied on the design of microstrip patch antenna. In this article, a novel technique is developed to apply bacterial foraging optimization technique in conjunction with the expressions developed to calculate accurately the resonant frequency of rectangular microstrip antenna of any dimension and of any substrate thickness. Further, bacterial foraging is applied to the calculatation of the feed point of microstrip antenna. The technique developed in this article can be a generalized soft computing tool to calculate resonant frequency of rectangular microstrip antenna. Similarly, the idea of the article can be used for calculating the various parameters of microstrip antennas of different structure and geometry. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

电除尘高频电源串并联混合谐振变换器的应用

介绍电除尘用高频电源的组成原理,分析串并联混合谐振变换器并给出实验结果,说明了采用该变换器的技术优越性。     

一种宽带天线的研究与设计*

为了满足宽带通信的需求,利用U形单极子天线和两个U形寄生辐射元的方法,设计了一种共面波导馈电的宽带天线,其阻抗带宽达到85%。所设计的天线印刷在尺寸为20 mm×30 mm×1.6 mm、介电常数为265的聚四氟乙烯介质基板上。为了满足无线局域网（WLAN）和全球互联微波接入（WiMAX）的工作需要,抑制不需要的信号,在U形单极子辐射元之间插入一条调谐微带线,产生一个陷波特性,使所设计的天线满足WLAN、WiMAX和低端UWB通信需求。利用高频结构仿真软件HFSS对影响天线性能的主要参数进行仿真、分析和优化,得到天线的优化尺寸,并对优化的天线进行制造和测试。实验结果表明,该天线比传统微带贴片天线性能有了较大的提高,证明了利用共面波导馈电和寄生技术设计宽带天线的可行性和有效性。     

一种高Q值硅微陀螺谐振频率快速锁定方法

提出了一种高Q值微陀螺快速锁定谐振频率的方法,可以减小其锁相环的调节时间。该方法基于高Q值微陀螺驱动模态受迫响应的瞬态分量包含谐振频率信息且持续时间长的特点,首先简要介绍了高Q值对锁相环锁定过程的影响,重点分析了其对锁频速度的影响;然后通过理论推导以及系统仿真验证了所提方法的可行性和有效性;最后基于FPGA设计了数字驱动电路,并对高Q值陀螺（Q值约为200000）进行驱动模态谐振频率锁定测试。试验结果表明,该方案可以有效控制压控振荡器（VCO）输出信号频率由初始频率迅速跳频至谐振频率附近,并由锁相环迅速锁定。     

微谐振传感器同频干扰的建模与消除

主要研究了静电激励/电容拾振谐振式硅微加速度传感器的同频干扰问题,分析了几种干扰源,建立了同频干扰的电路等效模型,提出一种基于双端激励/双端检测的结构,采用二次差分的方式消除同频干扰.     

电磁激励的硅谐振梁设计和有限元分析

介绍了电磁激励硅谐振梁的激励和检测原理,给出了双端固支的硅谐振梁谐振频率公式,并利用该公式分析了双端固支梁的谐振频率和梁尺寸的关系.本文利用有限元软件模态分析计算了三种不同的谐振频率情况,并逐一加以比较分析.本文还利用有限元软件对受力弯曲的工字梁做了静态分析,从而得出了在一定磁场力作用下的应力分布图,从而对压敏电阻的设计提供了一定的依据.     

低轨卫星通信终端微带天线设计与实现

针对低轨卫星通信系统中微带天线的特性要求,首先利用高频结构仿真软件HFSS建立微带天线模型,并对该模型运用电磁理论和优化理论进行仿真优化,得到了最佳的微带天线结构和电参数.然后根据设计参数研制了符合要求的中心频率为398 MHz的微带天线,并且缩减尺寸至可以植入卫星通信中的便携式终端设备.利用矢量网络分析仪对该天线各参数实测结果表明,研制的微带天线的性能与实际要求的指标吻合,证明了设计的有效性.     

Frequency tunable circularly polarized antenna with branch line coupler feed network for wireless applications

In this article, frequency tuning and circularly polarized concentric circular microstrip antenna is investigated. The proposed antenna consist of varactor diode for frequency tuning and branch line coupler (BLC) feed network to achieve the circular polarization (RHCP/LHCP). By changing the varactor diode capacitance between 12.33 pF (0 V) to 1.30 pF (15 V) attain the frequency tuning (2.34‐2.68 GHz). The right hand circular polarization (RHCP) and left hand circular polarizations (LHCP) are realized in the antenna through BLC feed network output ports. The impedance bandwidth (2.05‐3.13 GHz) of BLC feed network is well‐matched with the circular microstrip antenna frequency tunable bandwidth. The proposed antenna is fabricated, and simulated results are verified using the mathematical modeling and experimental verification.