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1.
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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《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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Ramirez R.R. De Flaviis F. Alexopoules N.G. 《Antennas and Propagation, IEEE Transactions on》2000,48(7):1040-1047
An analysis is presented for a microstrip-feed proximity-coupled ring antenna and a four-element array. Interactions between the embedded microstrip feed and the radiating element(s) are rigorously included. Results demonstrate that circular polarization of both senses can be achieved with a ring antenna with proper design of two inner stubs located at angles of ±45° with respect to the feedline. Theory and experiment demonstrate an axial ratio 3-dB bandwidth of 1% and the voltage standing wave ratio (VSWR) <2 bandwidth of 6.1%. The axial ratio bandwidth is typical for a microstrip antenna with perturbations, while the VSWR bandwidth is larger than for the circular or rectangular patch with perturbations. A mutual coupling study between two elements shows that the axial ratio is less than 2 dB for interelement spacing greater than 0.55λeff, while the VSWR <2 for all spacings considered. A comparison between theory and experiment is provided for a 2×2 element array. The benefits of sequentially rotating the antenna elements in an array environment are presented. The axial ratio and VSWR bandwidths are both increased to 6.1% and 18% for a four-element array. A single-element antenna with two orthogonal feeds to provide both senses of polarization is demonstrated. The ring antenna is small (D/λ0=0.325), the substrate thickness is thin (H/λ0~0.035), and the microstrip feed produces a completely planar antenna system, which is compatible with microwave and millimeter integrated circuits (MICs), and monolithic microwave integrated circuits (MMICs) 相似文献
4.
Nakano H. Eto J. Okabe Y. Yamauchi J. 《Antennas and Propagation, IEEE Transactions on》2002,50(1):17-24
A single-arm rectangular spiral antenna is analyzed using the finite-difference time-domain method. The spiral is printed on a finite-size dielectric substrate backed by a finite-size conducting plane. Both the substrate and conducting planes are square with a side length L of less than 0.6λ0 (λ0: wavelength in free space). The radiation pattern is dependent on the outermost arm peripheral length C. The spiral whose peripheral length is within 2λgg (λg: the guided wavelength of the current) radiates a tilted beam of circular polarization. When the peripheral length is decreased to λgg, the spiral radiates an axial beam. The axial beam has a wide half-power beam width of approximately 102° (for L≈0.369λ0) with a gain of approximately 6.7 dB. The axial beam shows a 15% frequency bandwidth for a 3 dB axial ratio criterion. Over this bandwidth, the voltage standing-wave ratio (VSWR) is less than two, as desired. The experimental results for the radiation pattern, gain, axial ratio, and VSWR are also presented 相似文献
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Yan Wai Chow Edward Kai Ning Yung Hon Tat Hui 《International Journal of Electronics》2013,100(5):587-593
An innovative monopole antenna coupled with a parasitic normal-mode helix has been designed and studied both experimentally and theoretically. The effects of various dimensions of the monopole and the parasitic helix were investigated extensively. This simple combination can significantly enhance the antenna bandwidth over that of the conventional monopole antenna. It is found that, with suitably chosen antenna dimensions, the VSWR bandwidth (VSWR ≤ 2) of the antenna can be increased to 36%, almost double that of the monopole antenna alone. The far-field pattern of the combined antenna is basically the same as that of the monopole antenna. This antenna is designed to operate at 1.8GHz. The substantially enhanced bandwidth of this simple and small antenna is a useful feature for future mobile communications. 相似文献
7.
Compact printed monopole antenna with 24:1 impedance bandwidth 总被引:1,自引:0,他引:1
A compact tapered CPW-fed hollowed elliptical printed monopole antenna with extremely wide bandwidth is proposed. The results demonstrate that this antenna achieves a measured impedance bandwidth from 0.44 to 10.6 GHz (24.1:1) for VSWR les 2, and exhibits a nearly omnidirectional radiation pattern, while its area is only about 0.18 times 0.13lambdal, where lambdal is the wavelength of the lowest operating frequency. 相似文献
8.
A broad-band coupled-strips microstrip antenna 总被引:1,自引:0,他引:1
A coupled-strip microstrip antenna with increased bandwidth and increased polarization purity is presented. We have demonstrated the underlying principle of its operation using even/odd modes of the coupled strips. An optimized parameter set for three coupled strips is obtained. The VSWR=2, impedance bandwidth of this antenna is 23% for antenna thickness of 0.083λ0 相似文献
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A novel dielectric resonator (DR) antenna is reported. The lowest order mode of the proposed antenna radiates like an electric monopole. The dimensions of the antenna are much smaller than a previously reported structure radiating in a similar mode, e.g. for an antenna fabricated out of εr=20 material, the diameter and height of the DR are ~0.08 λ0 each 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
13.
A Novel Compact Printed Antenna Used in TPMS or Other Complex and Variable Environments 总被引:1,自引:0,他引:1
A novel compact printed antenna used in tire pressure monitoring system (TPMS) is proposed and analyzed in this paper. The proposed antenna is printed on both sides of the dielectric substrate and the upper side consists of four parts: (1) the meandered radiating sections; (2) the additional strip line, which is used as a shorting connector and an additional radiating portion; (3) the feed microstrip line; and (4) the loading meandered sections, which are mainly used to improve the impedance bandwidth. The lower side consists of a meandered ground plane, which can also act as a balun choke and the extended parallel strap, which acts not only as a shorting connector but also as an impedance-tuning strap. A prototype of the proposed antenna with 0.17 lambda0 in length, 0.017 lambda0 in width and 0.0021 lambda0 in height has been fabricated and tested. The relative impedance bandwidth of the proposed antenna reaches 22% (VSWR < 3.0) and 12% (VSWR < 2.0), and the antenna has an acceptable relative gain and its performance is relatively stable. Therefore, it also can be used in other complex and variable environments besides TPMS. When the length of the antenna is reduced to 0.098 lambda0, the relative impedance bandwidth exceeds 28% (VSWR < 2.0). But the antenna's performance will become less stable, which may be the same as that of the conventional compact monopole antenna. Design details of the proposed antenna and the results of both simulations and experiments are presented and discussed. 相似文献
14.
The characteristics of a meander dual zigzag wire monopole antenna are described. The antenna provides low height and broad-band performance. Measured voltage standing-wave ratio (VSWR) and pattern characteristics are compared with a conventional, straight-wire monopole over a 3:1 bandwidth. 相似文献
15.
Nakano H. Suzuki N. Ishii T. Yamauchi J. 《Antennas and Propagation, IEEE Transactions on》2001,49(5):715-723
Three mesh antennas, all having an extremely small antenna height of approximately 0.06 wavelength above a ground plane, are presented. First, a mesh antenna excited with a balanced feed is analyzed. It is revealed that the mesh antenna radiates a linearly polarized wave with no cross-polarization component in the principal planes. The radiation mechanism is explained using the current distribution. Second, a mesh antenna excited with an unbalanced feed is analyzed. This antenna shows almost the same radiation characteristics as the mesh antenna with a balanced feed. The frequency bandwidth for a VSWR=2 criterion is evaluated to be approximately 3%. Third, a mesh antenna having two perturbation elements is analyzed. It is found that the antenna acts as a radiation element of circular polarization. The frequency bandwidth for a 3-dB axial ratio criterion is calculated to be approximately 1%. The mesh antennas in the first and second analyses can be used as dual linear polarization elements by appropriately switching the feed. Similarly, the mesh antenna in the third analysis can be used as a dual circular polarization element by switching the feed 相似文献
16.
The analysis is presented for a microstrip feed proximity coupled monofilar Archimedean spiral four-element antenna array. Interactions between the microstrip corporate feed and the radiating elements are rigorously included. Results demonstrate that circular polarization can be achieved with proper spiral arm length. Polarization of either sense is controlled by the location of the feedline. The 3-dB axial ratio (AR) and voltage standing wave ratio (VSWR) bandwidths are 9%. The antenna is small (2R/λ0=0.33) and the interelement spacing is 0.51λ0. The microstrip feed produces a completely planar antenna system, which is compatible with microwave integrated circuits (MIC) and monolithic microwave integrated circuits (MMIC) 相似文献
17.
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
18.
Modified planar inverted F antenna 总被引:4,自引:0,他引:4
Kin-Lu Wong Kai-Ping Yang 《Electronics letters》1998,34(1):7-8
The design of a modified planar inverted F antenna (PIFA) which is more compact (antenna length <λ0/8 and antenna height <0.01 λ0) and has a much wider antenna bandwidth (greater than 10 times that of a simple PIFA) is demonstrated. The reduction in antenna length is achieved by meandering the radiating patch, while the enhanced bandwidth with low antenna height is obtained using a chip-resistor load in place of the shorting post. A typical design of the modified PIFA in the 800 MHz band has been implemented, and experimental results are presented and discussed 相似文献
19.
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
20.
We report an improved cavity model called modified Wolff model (MWM) to compute the resonance frequency of a rectangular patch antenna on the thick PTFE substrate (0.037λg-0.229λg). The MWM accounts for the effect of anisotropy and total losses on the resonance frequency, therefore it has a maximum deviation 2% against the experimental results. The previous cavity model, the multiport cavity model, and MOM based commercial software, Ensemble, compute resonance frequency with deviation between 4%-36%. Results on the bandwidth computed by these models have also been compared against the experimental results 相似文献