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1.
Antennas based on the Soret and folded zone plates are analyzed using the body-of-revolution finite-difference time-domain method. Parametric studies of the focusing performance of these antennas are performed by varying the number of zones, the focal length, and the diameter of the zone plate. The results of the studies provide insight into the factors that influence the performance of these zone plate antennas and are used to generate accurate design graphs. The full analysis is validated by comparison with previously measured data for an integrated-circuit zone plate antenna 相似文献
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Grooved-dielectric, phase-correcting, Fresnel zone plate antennas are analyzed using the body-of-revolution finite-difference time-domain (BOR-FDTD) method. Parametric studies of the focusing ability of these antennas are performed to examine the effects of the focal length, diameter, number of zones, and the thickness of the lens, as well as the number of phase corrections per zone. The results of these studies are presented as design graphs and are used to lend insight into the focusing mechanism of phase-correcting zone plates. The BOR-FDTD analysis is validated by comparison with previous measurements. 相似文献
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Prakash P. Converse M.C. Webster J.G. Mahvi D.M. 《IEEE transactions on bio-medical engineering》2009,56(10):2470-2476
Microwave ablation (MWA) is a minimally invasive technique increasingly used for thermal therapy of liver tumors. Effective MWA requires efficient interstitial antennas that destroy tumors and a margin of healthy tissue, in situ, while minimizing damage to the rest of the organ. Previously, we presented a method for optimizing MWA antenna designs by coupling finite element method models of antennas with a real-coded, multiobjective genetic algorithm. We utilized this procedure to optimize the design of a minimally invasive choke antenna that can be used to create near-spherical ablation zones of adjustable size (radius 1-2 cm) by adjusting treatment durations and a sliding structure of the antenna. Computational results were validated with experiments in ex vivo bovine liver. The optimization procedure yielded antennas with reflection coefficients below -30 dB, which were capable of creating spherical ablation zones up to 2 cm in radius using 100 W input power at 2.45 GHz with treatment durations under 2 min. 相似文献
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Won‐Kyu Choi Seung‐Hwan Jeong Chan‐Won Park Cheol‐Sig Pyo Hae‐Won Son 《ETRI Journal》2014,36(6):881-888
This paper studies the magnetic coupling between two adjacent loop antennas that are parallel to each other in a plane and presents a new practical method to avoid the resulting magnetic coupling interference. The study focuses on the high frequency radio‐frequency identification (RFID) system for casino applications, where several loop antennas are closely built into a game table to monitor gaming chips. In this case, neighboring loop antennas may severely interfere with each other by magnetic coupling, which leads to the malfunction of the RFID system. In this paper, we present a practical loop antenna with a new loop switch circuit for avoiding magnetic coupling. The loop switch circuit is integrated with a matching circuit and automatically operated by using an interrogating signal from a reader. We verified the validity of the proposed design by showing that an RFID reader with the proposed antenna can exactly and separately read the gaming chips placed on the different betting zones of a game table. 相似文献
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Advancements in curtain-type high-frequency (HF) broadcast antennas are reviewed. Novel high-performance antennas for the Voice of America (VOA) are described, including vertical and horizontal beam selections, performance measurements, effects of finite ground and hills, radiation hazard zones, and transmission lines. Specifications for antennas to be installed at four new VOA stations are examined. The designs provide substantial flexibility in radiation-beam characteristics with four vertical beam modes and seven horizontal beam angles. it is believed that the technique of selecting the optimum radiation beam for ionospheric propagation to VOA target areas will provide a substantial improvement in the performance 相似文献
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根据微带天线的设计技术要求,介绍了微带天线带宽的影响因素。在矩形毫米波微带天线设计与分析的基础上,分别设计出 C 型和 W 型两种宽带毫米波开槽微带天线。利用仿真软件对3 种天线的输入回波损耗、驻波系数、相对带宽和方向性等技术参数进行仿真优化和比较分析。仿真与实验结果表明,3 种天线的设计均满足技术要求,C 型和 W 型开槽微带天线较矩形微带天线的相对带宽大幅提高,且具备良好的定向辐射特性。 相似文献
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The authors present a systematic process for the design of multimode quasi-integrated horn antennas, and provide a full range of practical antenna designs for millimeter- and submillimeter-wave applications. The design methodology is based on the Gaussian beam approach and the structures are optimized for achieving maximum fundamental Gaussian coupling efficiency. For this purpose, a hybrid technique is used in which the integrated part of the antennas is treated using full-wave analysis, whereas the machined part is treated using an approximate model. This results in a simple and efficient design process. The design procedure has been applied to the design of 20-, 23-, and 25-dB quasi-integrated horn antennas, all with a Gaussian coupling efficiency exceeding 97%. The designed antennas have been tested and characterized using both full-wave analysis and 91/370-GHz measurements. The quasi-integrated horn antennas are also examined as feed elements for Cassegrain antenna systems and are proved to be comparable to the traditional machined corrugated horn feeds 相似文献
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Zhi Ning Chen Xuan Hui Wu Hui Feng Li Ning Yang Chia M.Y.W. 《Antennas and Propagation, IEEE Transactions on》2004,52(7):1739-1748
This paper addresses two vital design considerations in ultrawide-band radio systems. One is that radiated power density spectrum shaping must comply with certain emission limit mask for coexistence with other electronic systems. Another is that the design of source pulses and transmitting/receiving antennas should be optimal for the performance of overall systems. The design of source pulses and transmitting/receiving antennas under the two considerations is discussed. First, the characteristics of transmitting/receiving antenna systems are described by a system transfer function. Then, the design of source pulses and transmitting antennas are studied based on the considerations for emission limits. Finally, the design of transmitting and receiving antennas are investigated in terms of pulse fidelity and system transmission efficiency. In the studies, thin wire dipoles with narrow bandwidths and planar dipoles with broad bandwidths are exemplified. 相似文献
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对陷波特性超宽带(UWB)天线的研究现状进行了分析总结.介绍了陷波特性超宽带天线的技术背景,分别对近年来陷波功能超宽带天线的设计进行了详细的评论,最后展望了陷波特性超宽带天线的未来发展方向. 相似文献
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小型平面超宽带天线的研究进展 总被引:5,自引:0,他引:5
对小型平面超宽带(UWB)天线的研究现状进行了分析总结.首先介绍超宽带无线通信的技术背景,描述了超宽带天线的几种常见定义.然后分别对小型超宽带印刷单极子天线的设计、小型超宽带缝隙天线的设计、具有陷波功能的小型超宽带天线的设计进行了详细的评论,并讨论了超宽带天线的性能评价方法.最后展望了小型平面超宽带天线的未来研究方向. 相似文献
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天线布局优化仿真研究 总被引:2,自引:0,他引:2
随着车载无线系统上装无线设备电磁环境日益复杂,设备间电磁干扰日益严重,采用仿真技术进行天线布局优化可以有效减小设备间干扰。本文分析了影响车载天线系统天线布局的主要因素,得出天线优化布局的优化目标为天线间的耦合度和方向图失真度,建立了天线布局优化模型,采用改进的遗传算法对车顶天线布局进行优化设计,在电磁兼容设计初期得出粗略的最佳布局方案,使其满足电磁兼容性能要求,降低了天线布局设计的难度,并设计了电磁兼容优化仿真软件,实现了车载系统的优化布局仿真,达到工程实际要求。 相似文献
13.
Bhobe A.U. Holloway C.L. Piket-May M. Hall R. 《Antennas and Propagation, IEEE Transactions on》2004,52(10):2545-2554
In microwave and millimeter wave applications, slot antennas fed by coplanar waveguide (CPW) lines are receiving increasing attention. These antennas have several useful properties, such as a wider impedance bandwidth compared to microstrip patch antennas, and easier integration of solid-state active devices. In this paper novel CPW-fed wideband slot antennas are presented. The design procedure of CPW-fed hybrid slot antennas (HSA) having impedance bandwidths (VSWR<2) up to 57% is described. Theoretical and measured results are shown. We also describe the design procedure of a CPW-fed log-periodic slot antenna (LPSA). The impedance matching and the radiation characteristics of these structures were studied using a method of moment technique. Simulated and measured results for different dielectrics are presented. 相似文献
14.
为了提高天线的容量和发射接收速率,LTE通信系统使用了MIMO天线。由于移动终端上空间有限,多个天线间存在较大耦舍,天线的辐射效率和通信容量会降低。为了解决这一问题,从S参数的角度推导出了天线的正交辐射模式,提出了通过加入180。耦舍器来降低多个天线间耦合的方法。使用HFSS和ADS对设计好的710MHz天线进行联合仿真,结果显示加入耦舍器后,两个天线间的耦合明显减小。这种设计使得该天线可以很好地应用于LTE通信系统的移动终端。 相似文献
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Mantravadi A. Veeravalli V.V. Viswanathan H. 《Selected Areas in Communications, IEEE Journal on》2003,21(3):382-394
The use of multiple antennas at the transmitter and the receiver is considered for the uplink of cellular communication systems. The achievable spectral efficiency in bits/s/Hz is used as the criterion for comparing various design choices. The focus is on wideband code-division multiple-access (CDMA) systems when the receiver uses the matched-filter or the minimum mean-squared error detector, followed by single-user decoders. The spreading sequences of the CDMA system are assumed to be random across the users, but could be dependent across the transmit antennas of each user. Using analytical results in the large system asymptote, guidelines are provided for the sequence design across the transmit antennas and for choosing the number of antennas. In addition, comparisons are made between (random) CDMA and orthogonal multiaccess with multiple antennas. It is shown that CDMA, even with single-user decoding, can outperform orthogonal multiaccess when the number of receive antennas is sufficiently large. 相似文献
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研究了有源相控阵天线的低成本设计思路和数字技术新方法。首先详细地分析了有源相控阵天线的系统构架和成本组成;然后从系统总体的角度,探讨了低成本数字阵列相控阵天线设计方法;最后提出了采用宽带宽角扫描的可重构设计技术来降低有源相控阵天线的成本。提出的有源相控阵天线低成本设计新方法具有很好的工程实用价值和科学意义。 相似文献
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Simplified design and analysis equations are presented for multiple-beam reflector antennas based on the Gaussian-beam analysis of the primary and secondary patterns. The derived equations are useful for the quick design and performance analysis in terms of the coverage-area directivity and the inter-beam isolation of multiple-beam antenna systems. Results of the analysis given in this paper agree well with rigorous computations based on physical-optics analysis of the reflector-antenna radiation patterns. Extension of the analysis to multiple-beam lens antennas, and to shaped/contoured-beam antennas, is also presented 相似文献