共查询到19条相似文献,搜索用时 468 毫秒
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研究天线性能优化问题,为了满足多个无线通信系统实现多系统收发共用,天线需在宽频带及不同频段下工作.为了得到优化的谐振频率和宽带,通过在矩形微带线上开两条对称的槽得到E型贴片天线,实现天线的双频功能,利用电磁仿真软件IE3D建立天线模型,通过IE3D对天线的性能进行仿真和分析,同时使用粒子群优化算法对其关键性参数进行了自适应优化,得出天线的具体尺寸.仿真结果表明,天线-10dB阻抗带宽分别为125 MHz(2400-2525MHz)和275MHz(5575-5850MHz),能够满足WLAN(2400-2484 MHz/5725-5825 MHz)的通信需求.优化的天线结构简单,具有很好的双频特性,在工作带宽内有很好的全向辐射特性. 相似文献
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星间链路天线指向的分析在卫星通信中非常重要.为了深入研究天线指向特性从而改善星间链路以及轨道构型的设计,通过仿真方法实现了星间天线指向的建模与分析.在介绍天线参数基础上,分析了天线方向图和天线指向模型.根据卫星是否同轨道面或同轨道高度,区别描述了4种不同情况下的天线指向特性.基于HLA/RTI构建了卫星网络仿真环境,通过建立由MEO、LEO卫星和地面站构成的仿真场景,对MEO卫星间链路和LEo/地面站与MEO卫星间链路的天线指向特性进行仿真,得出轨内和轨间星间链路在天线指向特性方面的差异,并提出对星间链路设计的建议. 相似文献
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导引头性能测试中,射频仿真的关键在于天线阵列辐射被试设备所需的目标回波,但天线三元组阵列的辐射特性即射频仿真系统的空域特性与导引头真实回波之间存在差异,并且难以解析表达,使得导引头测角误差的量化分析比较困难.针对上述问题,采用天线阵列电磁建模结合雷达导引头数学建模的方法,得到系统空域特性,计算其在不同目标位置引起的导引头测角误差.结果表明:射频仿真系统的空域特性会影响导引头的测角灵敏度和测角精度,而建立的模型能准确量化误差,便于修正三元组幅度控制指令以补偿测角误差,提高导引头接收信号角位置精度,增强导引头性能测试的可靠性. 相似文献
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针对标签天线在RFID系统中的重要性,基于微带天线设计和电磁场散射理论,设计和分析了一种具有感应反馈环的超高频段RFID标签天线。天线的谐振频率为915 MHz,尺寸为78 mm×23 mm,天线显示近线性相位特性,在电压驻波比小于2的条件下,天线的阻抗带宽为100 MHz。可以通过调整感应反馈环的长度来调整天线的谐振频率,天线的增益为2.5 dBi左右。通过仿真和测量可知,这种天线能较好地满足RFID超高频段标签的要求。 相似文献
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针对标签天线在RFID系统中的重要性,基于微带天线设计和电磁散射理论,设计和分析了一种具有匹配反馈环的微波段RFID标签天线。谐振频率为2.45 GHz和2.41 GHz天线的尺寸为54 mm×33 mm左右,天线显示近线性相位特性,在电压驻波比小于2的条件下天线的阻抗带宽为300 MHz。可以通过调整匹配反馈环的长度来调整天线的谐振频率,天线的增益为2.4~2.7 dBi。谐振频率为5.8 GHz的天线阻抗带宽为7%,增益为2.8~3.2 dBi,尺寸大小为20 mm×12 mm。通过仿真和测量可知,这种天线能较好地满足RFID微波段标签的要求。 相似文献
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Spectrum sensing with multiple antennas for cognitive radio systems in microcell environments is affected by the spatial correlation among multiple antennas.To reduce the adverse effects of the spatial correlation on the spectrum sensing performance,we employ multiple dual polarization antennas at the sensing node of secondary users.The analysis of the spatial correlation is derived using the propagation characteristics of the electromagnetic wave based on the scattering patch model in a multipath microcell environment.The superiority of spectrum sensing with multiple dual polarized antennas over multiple mono-polarized antennas is shown by analyzing the false alarm and detection probabilities with the correlation among the antennas in a microcell environment. 相似文献
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This article presents the Gui‐shaped Chinese character array antenna (GCCAA), which is loaded with the L‐shaped defect ground structure (LDGS) to improve isolation between the antennas. The GCCAA is obtained by arranging two Tu‐shaped antennas up and down. By etching a pair of LDGS on the ground, the direction of the coupling current is changed on the ground. Most importantly, the LDGS is not etched in the middle of the antenna elements, but loaded along the outer edge of the GCCAA, which not to destroy the appearance of the GCCAA and maintain the compact nature of the Chinese character. The measured results show that LDGS improves isolation from 15.4 to 37.4 dB when the antennas are placed with a 0.065 λ0 edge‐to‐edge distance. Meanwhile, it has little influence on reflection coefficient and radiation patterns. The decoupling technique is simple and straightforward which can be easy applied in Chinese character array antenna. 相似文献
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Expedited simulation‐driven design optimization of UWB antennas by means of response features 下载免费PDF全文
In this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature‐based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions is less nonlinear than for the original frequency characteristics (here, S‐parameters). This results in faster convergence of the optimization algorithm. The cost of the design process is further reduced using variable‐fidelity electromagnetic (EM) simulation models. In case of UWB antennas, the feature points are defined, among others, as the levels of the reflection characteristic at its local in‐band maxima, as well as location of the frequency point which corresponds to acceptable reflection around the lower corner frequency within the UWB band. Also, the number of characteristic points depends on antenna topology and its dimensions. Performance of FBO‐based design optimization is demonstrated using two examples of planar UWB antennas. Moreover, the computational cost of the approach is compared with conventional optimization driven by a pattern search algorithm. Experimental validation of the numerical results is also provided. 相似文献
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In this work, wire antennas are designed to jam GSM frequencies using genetic algorithms. These antennas are designed to block communication at 3-band GSM frequencies. They are planned to be mounted on a vehicle and therefore are modeled on a ground plane. Jammer antennas designed in this work are composed of wires, placed on two square dielectric frames, perpendicular to each other. Genetic optimization routines are developed on MATLAB environment for the designs carried out in this work. Electromagnetic simulation program called SuperNEC, which analyses antennas by the method of moments, is used to determine the antenna performances and is called by the developed GA routines. The purpose of the antenna optimization is to obtain low VSWR values and omni-directional radiation pattern near ground at θ = [70° 80° 90°] planes at all GSM frequencies, since the targets will be near ground for this application. Original and interesting antenna designs are obtained as the result of genetic optimization, and are presented in the paper. 相似文献
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Isolation enhancement between tightly spaced compact unidirectional patch‐antennas on multilayer EBG surfaces 下载免费PDF全文
In this article, ultracompact unidirectional patch antennas are used in different two‐antenna systems for biomedical applications at 5.2 GHz. Multilayer mushroom type electromagnetic bandgap (EBG) structures are designed as slow‐wave medium to reduce the size of the individual patch antennas to 0.1λ0 by 0.18λ0. Various techniques are investigated herein to improve antenna isolation for an enhanced Multiple‐Input Multiple‐Output (MIMO) performance. First, the coupling between 0.3λ0‐spaced antennas is verified to occur dominantly through radiation and near‐field coupling between the patches rather than through substrate‐bound modes. Second, various configurations are proposed to suppress antenna coupling. These approaches include reorientation of the antennas and employment of parasitic radiators between the patches. A novel design is presented in which a unidirectional parasitic slot radiator on an EBG reflector is inserted between the antennas to decouple them. Measurement results confirm efficacy of these approaches in mitigating antenna coupling by more than 11 dB in the operating bandwidth of the antennas. The compact patch antennas maintain efficiency values of higher than 70%. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:30–38, 2015. 相似文献
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This paper presents a reconfigurable terahertz Vivaldi antenna based on a hybrid graphene‐metal structure. The proposed antenna uses a novel tapered slot edge with hybrid graphene‐metal structure to improve the electromagnetic characteristics of classical metallic Vivaldi antennas. The results show that the proposed hybrid graphene‐metal Vivaldi antenna can be dynamically reconfigured via electric field bias, and has a low reflection coefficient. Moreover, this study demonstrates that the proposed antenna has excellent gain and radiation efficiency than that of the graphene Vivaldi antenna, and brings more possibilities to the realization and application of graphene antennas in the terahertz band, which is expected to use in terahertz wireless communication in the future. 相似文献