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八木天线是一种常用的天线形式.本文将Minkowski分形环应用于八木天线设计中,利用分形结构的空间填充特性来减小天线的横向尺寸,从而实现天线小型化设计.设计了工作于880~960MHz的6元二阶Minkowski分形环八木天线,以矩量法为核心对设计天线进行数值分析,将线天线模拟为细带线模型,天线表面采用三角单元进行剖分,RwG基函数作为电流展开函数.同方环八木天线进行了比较,在驻波特性、辐射特性相似情况下,分形环八木天线的尺寸缩减了29.8%. 相似文献
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为了克服正交磁环天线结构误差角造成的测向角度(测角)误差较大的问题,该文提出一种结构上改进的三磁环测向天线设计方案。阐述了两两呈60°夹角磁环嵌套结构的三磁环天线的测向原理,建立了三磁环天线测角误差关于结构误差角的仿真模型。仿真分析表明,在相同结构误差角的条件下,相比正交磁环天线,三磁环天线测角误差最大值理论上能够降低50%。低频(f<200 kHz)情况下的对比实验结果表明,相比于正交磁环天线,三磁环天线测角误差最大值降低65%,测角误差总体优化约50%,实验与仿真结果符合较好。 相似文献
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RongLin Li Bo Pan Traille A.N. Papapolymerou J. Laskar J. Tentzeris M.M. 《Antennas and Propagation, IEEE Transactions on》2008,56(2):312-318
A cavity-backed loop antenna is developed for producing broadband circularly polarized (CP) radiation. The antenna configuration consists of a slot loop and a strip loop. The slot loop radiates a CP wave at a lower frequency while the strip loop produces CP radiation at a higher frequency. A combination of the two frequencies leads to a bandwidth enhancement. The slot/strip loop antenna is fed by a single straight microstrip line. It is demonstrated that the cavity-backed slot/strip loop antenna can achieve an axial ratio (les 3 dB) bandwidth of 19% with good impedance matching. The antenna configuration is described and the operating principles for broadband circular polarization and impedance matching are analyzed. The antenna performance is confirmed by experimental results. 相似文献
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应用矩量法计算了折线电天线、方形环天线和加载电容方形环天线的电流分布,计算结果表明:当加载电容的方形环天线所加载的电容很大或很小时,其电流分布分别与闭合环天线和开路折线电天线的电流分布相吻合;并在此基础上进一步计算和分析了不同频率下环路闭合与开路的天线辐射场,研究结果对分析电磁兼容共模辐射问题有一定的参考价值. 相似文献
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复合材料垂尾隐蔽式短波天线研究 总被引:1,自引:0,他引:1
为研究复合材料垂尾对机载短波天线输入阻抗和辐射特性的影响,分析了不同机载隐蔽式短波天线的结构和性能,提出了一种基于复合材料垂尾的新型回线天线结构,并利用基于时域有限差分法的仿真软件XFDTD对这种位于机垂尾前缘的隐蔽式回线天线和传统的机载套筒天线分别进行了建模和仿真。根据仿真结果分析并总结出了复合材料垂尾对这两种机载短波天线输入阻抗和辐射特性的影响情况。通过与传统回线天线的比较,验证了新型回线天线的可行性和优势。仿真结果对实际机载短波天线的研究和设计有一定的参考价值。 相似文献
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RongLin Li DeJean G. Laskar J. Tentzeris M.M. 《Antennas and Propagation, IEEE Transactions on》2005,53(12):3930-3939
It is demonstrated that the bandwidth of circular polarization (CP) can be significantly increased when one more parasitic loop is added inside the original loop. A single-loop antenna has only one minimum axial ratio (AR) point while the two-loop antenna can create two minimum AR points. An appropriate combination of the two minimum AR points results in a significant enhancement for the CP bandwidth. A comprehensive study of the new type of broad-band circularly polarized antennas is presented. Several loop configurations, including a circular loop, a rhombic loop, and a dual rhombic loop with a series feed and a parallel feed, are investigated. The AR (/spl les/2 dB) bandwidth of the circular-loop antenna with a parasitic circular loop is found to be 20%, more than three times the AR bandwidth of a single loop. For the rhombic-loop antenna with a parasitic rhombic loop, an AR bandwidth (AR/spl les/2dB) of more than 40% can be achieved by changing the rhombus vertex angle. The AR (/spl les/2 dB) bandwidths of the series-fed and parallel-fed dual rhombic-loop antennas with a parasitic element are 30% and 50%, respectively. A broad-band balun is incorporated into the series-fed dual rhombic-loop antenna for impedance matching. The broad-band CP performance of the loop antennas is verified by experimental results. 相似文献
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A novel miniaturized cavity-backed composite slot loop antenna (CBCSLA) with low profile and omnidirectional radiation similar to a short dipole is presented. The antenna displays vertical polarization while having less than lambda/100 dimension in height. The geometry of the antenna is inspired from a small magnetic loop which is realized using a slot configuration on metallic ground. Since a small slot loop antenna cannot be impedance matched, a composite geometry is devised that acts like as a small slot loop and can easily be impedance matched using this configuration. The diameter of the CBCSLA can be made as small as lambda/10 or smaller. The feeding mechanism is designed in a manner to create a circumferentially-constant current distribution around the composite loop while effectively matching to a 50 Omega coaxial feed from the antenna center. Additional methods are discussed to further enhance the bandwidth and achieve a dual-band response. The antennas are designed, fabricated, and measured. It is shown that despite their small lateral dimension and extremely small height, the miniaturized cavity-backed slot loop features extremely well input impedance match, uniform radiation pattern, low cross-polarization levels and expected gain. 相似文献
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The distribution of current, admittance, and far field of a shunt-driven circular loop antenna are derived and related to those of an equivalent series-driven loop in parallel with a section of transmission line. The effective length of a shunt-loaded receiving antenna is obtained in terms of the corresponding quantity for the series-loaded loop. 相似文献
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Yang G.M. Daigle A. Liu M. Obi O. Stoute S. Naishadham K. Sun N.X. 《Electronics letters》2008,44(5):332-333
A circular loop antenna with self-biased magnetic film loading at 1.7 GHz is presented. The proposed circular loop antenna is realised by cascading a microstrip loop and a tuning stub. Self-biased NiCo-ferrite magnetic films were used to tune the working frequency of the loop antenna. Three different cases of antennas with films loading were designed and analysed. Antennas with self-biased magnetic films loading working at 1.7 GHz with a tuning range of 50-400% of the antenna bandwidth were achieved. 相似文献
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在车载动中通卫星通信系统中,为了隔离天线载体姿态变化对天线指向的扰动,天线伺服环路常采用陀螺稳定外套自跟踪环路和引导位置环路的多环路设计。对于采用A-E轴系座架卫星通信动中通天线,天线座A轴的运动与天线指向在H面的运动之间存在一个正割关系,因此在环路设计时需要进行正割补偿。通过传递函数结构图分析,详细论述了在不同位置引入正割补偿对伺服环路的影响,确定了正割补偿设置方案。 相似文献
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The radiation properties of parasitic loop counterpoise antennas are investigated in detail. It is found that the parasitic loop concept can be used advantageously to reduce considerably the undesirable effects produced in loop counterpoise antenna patterns due to the counterpoise edge diffraction effects. Results of extensive numerical and experimental investigation of various aspects of the parasitic loop counterpoise antenna patterns are reported. The method of design of such antennas is also discussed. Three such new antennas are proposed which appear to be capable of bringing out superior performance from the present-day VOR system. 相似文献
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Analysis of a printed wire loop antenna 总被引:2,自引:0,他引:2
《Microwave Theory and Techniques》1994,42(2):227-233
The current distribution and radiation pattern of a printed thin-wire circular loop antenna are computed rigorously using an entire-domain moment method analysis. A computationally efficient algorithm using the FFT is implemented. The input impedance of the loop and the far-zone radiation pattern are computed as a function of the substrate dielectric constant and thickness and as a function of the loop circumference. The space-wave launching efficiency and z-directed power gain of the antenna are also computed as a function of the substrate thickness 相似文献
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A linearized hydrodynamic theory and potential function technique arc used to formulate the theory of a corner-driven loop antenna immersed in a warm plasma. The theory explains some of the experimental observations obtained from impedance measurement of a loop antenna on the Ariel 3 satellite. The far-zone fields and the normalized radiated power for different antenna sizes are calculated. The results suggest that much of the radiated energy is radiated in longitudinal plasma waves 相似文献
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The analysis of antenna configurations in the form of a generalized superquadric loop, which includes circular, elliptical and rectangular loop geometries, is presented in this paper. Use of a Galerkin form of the moment method with piecewise sinusoidal subsectional basis and testing functions provides rapid numerical convergence and accurate representation of the antenna current. A convenient parametric representation for the superquadric curve is developed to allow a subsectional formulation using curved wire segments, rather than the commonly employed piecewise linear segments, to construct the geometry. Both magnetic frill and delta gap source models are implemented to allow a detailed study of input impedance, directivity, radiation pattern and current distribution as a function of various geometrical parameters. The results are shown to compare well with previous results for the special case of a circular loop antenna. Some useful curves are presented to aid in the design of practical superquadric loop antennas 相似文献
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Le-Wei Li Mui-Seng Yeo Mook-Seng Leong 《Antennas and Propagation, IEEE Transactions on》2004,52(9):2391-2402
This paper presents derivation and computation of electromagnetic (EM) fields inside a dielectric prolate spheroid radiated by a loop antenna. The dielectric spheroid is considered to be multilayered, and a thin circular loop antenna that is loaded by a voltage source radiates on the top of the prolate spheroid. The multiple interaction of transmitted and reflected waves with the spheroid is characterized by applying the method of moments (MoM) to both the circular loop antenna wire and the stratified spheroidal interfaces. The dyadic Green's function in the expansion form of eigenvector wave functions is used to derive the EM fields, so the formulation is quite compact. Different basis and weighting functions are used inside the method of moments procedure for obtaining in an efficient way the unknown current distributions along the antenna wire and the unknown expansion coefficients of their resulted EM fields. Current distributions and the transmitted fields inside the spheroidal model are computed numerically and the convergence issues are discussed. 相似文献