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A sleeve-cage monopole has parasitic wire elements that form a sleeve around the driven cage antenna. Appropriate placement and dimensions of the wire parasites lead to bandwidth enhancement. Genetic algorithms and an integral equation solver are employed to determine the position and lengths of the parasitic wires in order to minimize voltage standing wave ratio (VSWR) over a band. The cage is replaced by a normal-mode quadrifilar helix for height reduction and the resulting structure is referred to as a sleeve helix. Measured VSWR and input impedance data are in good agreement with computed data. A fabricated sleeve-cage monopole has a bandwidth ratio of 4.4:1 and a sleeve helix has a bandwidth ratio of 3.5:1 for measured VSWR less than 3.5. 相似文献
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Nakano H. Ikeda N. Yu-Yuan Wu Suzuki R. Mimaki H. Yamauchi J. 《Antennas and Propagation, IEEE Transactions on》1998,46(6):788-793
The effects of parasitic elements on the voltage standing wave ratios (VSWR's) of two antennas are investigated. First, a parasitic monopole is used for a normal-mode helical antenna. The VSWR investigation shows that dual-frequency operation is obtained by the parasitic element effects. The dual-frequency operation is revealed as a function of monopole position above a ground plane (monopole height). As the monopole height decreases, the separation of a higher resonance frequency fH from a lower resonance frequency fL increases. For a monopole length of LMP≈0.4λHX , where λHX is the resonance wavelength of the helix, the frequency bandwidth for a VSWR=2 criterion is 12.5% in the lower frequency fL region and 5.2% in the higher frequency f H region, with a frequency separation ratio of fH/fL=2.14. Secondly, L-figured parasitic elements are used for an inverted-F antenna (IFA). The parasitic elements improve the VSWR performance. The frequency bandwidth for a VSWR=2 criterion is approximately two times as wide as that of the single IFA. It is also found that bending the horizontal sections of the IFA and parasitic elements contributes to reducing the antenna size while not significantly deteriorating the VSWR bandwidth. The radiation patterns are also presented and discussed 相似文献
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《Electronics letters》2003,39(23):7
A novel kind of planar monopole broadband antenna with a parasitic radiator is presented. Measurements show that the bandwidth of the monopole antenna has been considerably improved with a parasitic element earthed with a matching inductor. The achieved impedance bandwidth reaches over 85% for VSWR/spl les/2, and the measured radiation patterns have little distortion when the frequency changes. The impedance bandwidth parameters are compared for different dimensions of ground planes 相似文献
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设计了一种具有双陷波特性的平面超宽带天线。超宽带基础天线的馈电采用渐变式阶梯阻抗匹配结构作,使得天线具有了宽阻抗匹配能力。通过在椭形辐射器内进行开窗,以及在地面添加矩形寄生单元,实现了天线的双陷波特性。测试结果表明,该天线的工作带宽(VSWR<2)为3.1~10 GHz,工作在超宽带(UWB)频率范围,两个陷波分别在3.3~4.0 GHz和5.0~5.85 GHz,可以应用于WiMAX和WLAN频段的信号抑制。仿真与实测结果表明,该天线结构简单、实现了良好的陷波功能,能够较好地应用于超宽带通信系统中。 相似文献
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A small broadband disc-loaded monopole antenna with a probe feed and folded stripline is presented. The antenna is composed of a rectangular disc with multiple shorting pins and a probe feed with a folded stripline that are coupled electromagnetically. The dimensions of the proposed antenna are 12/spl times/12/spl times/10 mm, and it has a measured impedance bandwidth of 700 MHz for VSWR <2 with a centre frequency at 2.54 GHz, which is approximately 27.5% of a fractional bandwidth. 相似文献
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A novel multiple meander strip monopole antenna is presented. By iteratively meandering the vertical strip, compactness and broadband characteristics for the monopole antenna were achieved simultaneously. The designed monopole antenna with a radiation element volume of 14/spl times/14/spl times/14 mm/sup 3/ has the measured bandwidth ratio of 3.87:1, from 2.83 to 10.96 GHz for VSWR/spl les/2, with fairly frequency-insensitive omni-directional radiation characteristics. 相似文献
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Printed annular monopole antenna for ultra-wideband applications 总被引:3,自引:0,他引:3
A novel printed monopole antenna for ultra-wideband applications is introduced, which consists of an annular monopole patch and a trapeziform ground plane with a tapered CPW feeder in the middle. The simulated and experimental results demonstrate that this antenna achieves a ratio impedance bandwidth of more than 10:1 for VSWR/spl les/2, and exhibits the nearly omnidirectional radiation pattern with a simple structure. 相似文献
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为了解决车载通信天线工作频带窄、尺寸大等缺点,文中提出了一款应用于车载鲨鱼鳍外壳的新型小型化、宽带MIMO天线。为了实现天线的宽带特性,充分利用了印制单极子天线易于引入多谐振的特点,首先通过合理的尺寸设计,将单极子天线谐振频率设计至工作频段中;然后,使用缝隙加载技术,增加天线谐振模式数量并改善天线阻抗匹配特性,拓宽了天线带宽并实现了天线的小型化。为了验证天线实际性能,将天线安装于鲨鱼鳍外壳中进行了测试。结果表明,该天线可以覆盖824~5 000 MHz的频段范围,驻波比均小于3,增益最低1.9 d Bi、最高6.2 d B,效率均高于49.5%、最高达89.2%。该天线可满足车载通信系统对天线的宽带化和小型化要求。 相似文献
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针对传统八木天线体积过大,难以与其他载体共形,相对带宽很窄的问题,设计了一种宽带微带八木天线。天线采用一种比较简单的馈电方式减小天线的尺寸,利用附加寄生贴片、振子耦合枝节和金属化孔的方式展宽频带和改善天线的阻抗匹配。使用Ansoft公司高频结构仿真器(HFSS)对天线进行仿真设计和优化,并对实物进行测试。最后结果表明,所设计、制作的天线频段在1.81~2.57 GHz内,电压驻波比(VSWR)小于2,相对带宽为31%,在2.4 GHz频率处的增益大于9 dB。仿真和测试结果显示,该宽带微带八木天线基本达到设计要求。 相似文献
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设计了一种小型化宽带定向天线。椭圆形的印制单极天线是一种小型化的超宽带天线,通过将该单极天线的地板折叠为字母C的形状,作为单极天线振子的反射腔,不仅实现了天线的定向性,同时进一步减小了天线的高度尺寸(0.13λ0,λ0为工作频率空气波长)。制作了天线样件并进行了测试,实测结果表明,该小型化天线驻波小于3的工作带宽为700~3800MHz,天线的方向图在整个频带内具有良好的定向辐射特性。 相似文献
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Wide-band planar monopole antennas 总被引:10,自引:0,他引:10
The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency corresponding to the lower edge of the bandwidth for each of these configurations. The elliptical disc monopole (EDM) with ellipticity ratio of 1.1 yields the maximum bandwidth from 1.21 GHz to more than 13 GHz for voltage standing wave ratio (VSWR)<2 相似文献
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I-Fong Chen Chia-Mei Peng Sheng-Chieh Liang 《Antennas and Propagation, IEEE Transactions on》2005,53(4):1270-1273
The ability of a single layer strip fed printed monopole, which has a serial-slot and an end-stepped feed-strip, to operate at dual Industrial, Scientific, and Medical-band (2.4 and 5.8 GHz bands) is demonstrated. This antenna combines omni-directional and broad bandwidth in an easy to fabricate structure. Experimental results indicate that the VSWR 2:1 bandwidths achieved were 8.2% and 18.2% at 2.45 GHz and 5.5 GHz. Effects of varying the serial-slot dimensions and the ground-plane size on the antenna performance are also described. 相似文献
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A wide-band, electrically small, disk-loaded antenna, comprising of a disk, 0.26 wavelength (at midband) in diameter, located 0.097 wavelength above a ground plane, has been designed and tested. A unique experimental procedure was used to determine the parameters of the impedance matching network, which consists of a conductive biconical center post and two structural side posts located in the space under the disk. The resulting antenna has a maximum voltage standing-wave ratio (VSWR) of 2:1 over a frequency bandwidth ratio of approximately 2:1. A second model, designed using the same technique, has a maximum VSWR of 3:1 over a frequency bandwidth ratio of 3:1. This antenna was compared to a multi-element disk-loaded antenna (with the same size profile) designed by Dr. Georg Goubau. This multi-element antenna also has a maximum VSWR of 2:1 over a frequency band of approximately 2:1. The comparison shows that the simple disk-loaded antenna, with fixed double tuning, achieves the same low VSWR as the multi-element disk-loaded antenna with fixed triple tuning. Therefore, an increase in bandwidth could be achieved in the simple disk-loaded antenna by applying higher order tuning. 相似文献
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A unique approach is described for widening the bandwidth of a helical antenna with improved gain, pattern, and axial ratio characteristics. The antenna may be described as a nonuniform or quasi-taper helix, which consists of a combination of uniform and tapered helix sections. Measured patterns, gain, axial ratio, and VSWR for various helical antenna configurations are presented and compared. It is shown that a nonuniform quasi-taper helix can provide an operating bandwidth twice that of a conventional uniform-diameter helix. 相似文献