共查询到20条相似文献,搜索用时 31 毫秒
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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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A planar and miniature (0.09lambda times 0.13lambda) radio frequency identification (RFID) tag antenna is described whose radiation pattern is near omni-directional in three dimensions, with less than 2.6 dB gain deviation in all directions. The antenna is comprised of an open-loop radiating element, which is excited by a small loop. The minimum and maximum read ranges of the implemented RFID tag are approximately 2.3 and 2.6 m, respectively. Comparison between the simulated and measured results for the radiation and read patterns are shown to be in good agreement. 相似文献
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A novel wire-loop antenna is introduced for circular polarization. By introducing a small gap at the middle of two nonradiating sides of a one-wavelength square wire loop, a 90/spl deg/ time-phase difference between the currents on the other two radiating sides can be achieved. Then by twisting the square loop to make the radiating sides orthogonal the necessary conditions are satisfied for circularly polarized radiation. The antenna yields nearly ideally circular polarization at broadside as well as excellent input impedance properties near the design frequency. The radiation pattern has a broad beamwidth and good rotational symmetry about the axis. For a demonstrator operating at 1 GHz, a 3-dB axial ratio was maintained over /spl plusmn/30/spl deg/. The mechanism of circular polarization is analyzed based on numerical simulation. Experimental results are presented to verify the theoretical predictions made. 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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J. A. Ansari Kamakshi Kumari Ashish Singh Anurag Mishra 《Wireless Personal Communications》2013,69(4):1365-1378
In this paper, a comparative study of co-planar gap coupled rectangular and elliptical microstrip patch antenna is presented. It is analyzed by using circuit theory concept. The proposed antennas show ultra wideband operations which depend on dimensions of the patches, gap between them as well as air gap thickness. It is observed that the performance of gap coupled elliptical patch antenna is better than that of rectangular patch antenna while the area of rectangular and elliptical patches is same. The bandwidth of proposed rectangular patch antenna is found to be 50.7 % with average gain of 6.5 dBi while for elliptical patch antenna the bandwidth and gain further improves up to 57.6 % and 9.5 dBi respectively. The theoretical results are in good agreement with the simulated results obtained from IE3D simulation software. 相似文献
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Ronglin Li Gerald Dejean Manos M. Tentzeris Joy Laskar 《Wireless Personal Communications》2007,42(1):1-11
A new type of multi-broadband antennas is developed for wireless applications. The broadband performance of this type of antennas
is achieved by introducing a small gap on a wire loop while the multi-band operation is realized by simultaneously exciting
one or more additional wire elements. Three antenna configurations are investigated for single-, dual-, and triple-broadband
operations. The dual-broadband operation is obtained by employing a combination of a loop and a monopole. The triple-broadband
antenna consists of a loop, a monopole, and an inverted-L structure. It is demonstrated that the multi-broadband antennas
can achieve a bandwidth of 30% in the 1GHz band, 50% in the 2 GHz band, and 40% in the 5 GHz band, which cover the frequency
bands for AMPS/PCS, GSM/DCS, PDC/PHS, and IMT-2000 mobile communications as well as for 2.4-GHz and 5-GHz wireless applications. 相似文献
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A design for a small and tunable loop antenna is presented. This design enables the higher-order mode resonant frequency to become low while keeping the radiation pattern in good shape. The use of a tunable circuit to utilise higher-order mode for bandwidth enhancement has been investigated. The measured and simulated radiation patterns and voltage standing wave ratio are given. 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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A novel and compact electrical loop antenna for an RFID reader at 433.92 MHz is proposed. Using modified and stacked patches, in-phase and uniform currents are excited so that an omnidirectional radiation pattern with a /spl phi/-component of the electric field is obtained. The antenna is analysed based on simulated and measured results. 相似文献
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A small circular loop antenna is located in an insulating layer within a dissipative medium. The admittance of the loop is calculated using a two-term trial function for the loop current in a variational formulation. Thin insulating layers tend to maintain a nearly uniform current around the small loop, in particular for highly lossy surrounding media. The assumption of a uniform loop current is shown to be justified for a range of antenna parameters. 相似文献
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Circularly polarized metallic EBG antenna 总被引:1,自引:0,他引:1
Diblanc M. Rodes E. Arnaud E. Thevenot M. Monediere T. Jecko B. 《Microwave and Wireless Components Letters, IEEE》2005,15(10):638-640
This letter describes the concept and the realization of a directive and circularly polarized antenna using an electromagnetic band gap material whose circular polarization is generated by the structure itself. Experimental and simulated results are presented for an antenna operating at 5GHz. 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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本文介绍了一种通过加载电磁带隙结构(Electromagnetic band gap,EBG)反射板来辐射圆极化电磁波的偶极子天线。该EBG反射板由矩形单元组成7×5阵列,印制偶极子天线谐振中心频点是5.2GHz。从仿真结果看,该偶极子天线能够有效地辐射圆极化波,阻抗带宽达到了0.65GHz,极化带宽达到了0.13GHz,天线增益达到了7.8 d B。 相似文献
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The loop cell used for calibration is fabricated using two intersecting metal sheets joined at the intersection and forming a 360 angle. A section of a loop is mounted between two coaxial panel jacks, one on each sheet located at a distance equal to the loop radius from the intersection. A known current through this section of electrically small loop produces calculable E and H fields between the sheets in the plane of the loop. These known fields may be used to determine the antenna factor of small E and H antennas placed in the field if the mutual impedance due to the antenna images in the sheets is negligible and the antenna is not close to the open edges of the cell. Measured and calculated antenna factors agree within ± 2 dB between 0.25 and 1000 MHz. 相似文献
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Closed-form expressions are derived for the input impedanceZ of a small loop antenna with arbitrary orientation in a cold collisionless uniform multicomponent magnetoplasma. The closed-forms results ofZ are compared with numerical results from a full-wave formal solution. It is found that for small loops these approximate formulas adequately represent the loop input impedance. 相似文献
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