共查询到20条相似文献,搜索用时 15 毫秒
1.
The feasibility of obtaining arbitrary polarization in both one- and two-dimensional arrays of slots in dual mode bifurcated Waveguides has been demonstrated. The radiating element consists of a pair of crossed slots in the sidewall of a bifurcated rectangular waveguide that couple to even and odd waveguide modes. One linear polarization is excited by the even or "sum" mode and the orthogonal linear polarization is excited by the odd or "difference" mode. By superposing the sum and difference modes in the proper amplitude and phase, any arbitrary polarization can be realized. A two-dimensional array consisting of eight waveguide linear arrays, ferrite phase shifters for scanning in the plane normal to the linear arrays, and a feed network for power distribution and polarization control was constructed. Good radiation performance for various polarizations was obtained. In the case of linear polarization, the cross polarization component was on the order of -25 dB and in the case of circular polarization, the axial ratio was on the order of 1 dB. The polarization was controlled with a ferrite phase shifter. Close-in sidelobes of better than 20 dB were obtained for all polarizations. The preceding performance characteristics were obtained over a scan range ofpm20deg and over a 6 percent frequency band. 相似文献
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The effect of internal higher order modes in the feeding waveguide of a planar slot array is investigated. Both the centered-inclined coupling slot and the longitudinal-transverse coupling slot are considered. Method of moments solutions to pertinent coupled integral equations are investigated for arrays of coupling slots of the centered-inclined and longitudinal-transverse types between a main waveguide and crossed branch waveguides. It is demonstrated that, by including the TE/sub 20/ mode coupling in the analysis, most of the higher order mode effects can be accounted for in reduced height waveguides, whereas in waveguides of standard height there may be a small additional effect arising from the TE/sub 01/ mode coupling.<> 相似文献
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A novel antenna array that radiates a single mode of multiple coupled nonradiative dielectric (NRD) waveguides, is described. The array is fed by a single NRD waveguide, which is designed to propagate a wave with the same wave number as that of free-space. The individual radiators of the array are spaced at one free-space wavelength, but due to the narrow beamwidth of the individual radiators, grating lobes are effectively suppressed. An eight-element array is described and measurements presented, but the design method can be extended to any number of elements 相似文献
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The characteristics of a radiating rectangular transverse slot in a rectangular waveguide have been studied. A moment method solution is used with entire basis expansion and testing functions (Galerkin) including the effect of wall thickness. The results are presented in terms of normalized resistance and reactance versus slot length and frequency. Excellent agreement with a previous pulse basis solution is found, as well as with measured data. An array of resonantly spaced transverse slots radiates large grating lobes. A spatial filter using baffles to suppress the grating lobes is described, suppressed. The effect of the baffles on the transverse slot impedance is analyzed for the case of baffles with infinite height 相似文献
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An efficient numerical procedure for determining the radiation characteristics of an infinite periodic array of slots in a conducting screen is presented. The procedure employs a novel mixed-potential integral equation formulation and is solved by the method of moments. Subdomain-type basis functions are used to provide the flexibility to model arbitrarily shaped slots. Analysis is carried out to account for dielectric layers, ground planes, or cavities placed on either side of the slot. Series acceleration techniques are employed to reduce significantly the computation time required to sum the series representing the periodic Green's function. The numerical scheme developed is applied to obtain quantities such as the slot field distribution and input admittance as a function of the array scan angle. Where possible, numerical results obtained are compared with data available in the literature. Data for the half-space case are found to agree with those of A.Y. Grinev et al. (1978) except for the case of multilayer dielectric loading 相似文献
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Kumar S.J. Chakraborty A. Das B.N. 《Antennas and Propagation, IEEE Transactions on》1991,39(6):851-854
A method of scanning a one-dimensional shaped pattern generated by a tilted circular planar array of nonisotropic elements is presented. A method of synthesis of phase function for a desired cosecant pattern and specified amplitude distribution for excitation of the elements of the array is presented. The phase distribution required in the perpendicular direction for retaining the beam shape in the scanned plane is determined. Computed results on the phase distribution and radiation pattern are presented. The appropriate correction is applied to get a better agreement between the realized and desired patterns in this scanned position of the beam 相似文献
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This paper deals with mutual coupling in a finite planar array antenna, composed of open-ended circular waveguides in a ground plane. The element-by-element approach is used and the problem is formulated as an integral equation, by requiring the transverse electric and magnetic fields to be continuous across the apertures. The equation is then solved by the method of moments and the mutual coupling in a 127-element array is computed. Excellent agreement with measurements and with the active reflection coefficient for the corresponding infinite array is found. The presented method of coupling analysis can be considered as a supplement to the established periodic-structure approaches for infinite arrays and may be useful for the analysis of small or nonperiodic arrays. 相似文献
9.
A ridge waveguide longitudinal-slot antenna array with a compact transverse dimension is introduced. To broaden the bandwidth of the array, it is divided into two sub-arrays fed by a novel compact convex waveguide divider. A 16-element uniform linear array at X-band was fabricated and measured to verify the validity of the design. The measured bandwidth of S/sub 11//spl les/-15 dB reaches 14.9% while the measured cross-polarisation level is less than -36 dB over the entire bandwidth. 相似文献
10.
Li Zhixin 《电子科学学刊(英文版)》1985,2(4):345-349
This paper proposes a simple method for measuring the admittance of the inclined slot on Hplane of rectangular waveguide of
a slot array, and the measured results are given. 相似文献
11.
Active Doppler velocity sensors require an antenna system that generates three or more independent beams. A four-port dual-mode antenna that generates four independent beams from a single aperture is described. The signals emanating from the four ports generate four beams in space through a common aperture of crossed slot radiators. Isolation between the four signals processed through the antenna is obtained primarily by utilizing the mode isolation that exists between theTE_{10} andTE_{01} modes in square waveguide. The isolation obtained between ports was 27.5 dB or greater. The special design problems and the effect of dimensional tolerances on the port isolation are discussed. A gain of greater than 30 dB for each beam and an overall antenna efficiency of approximately 71 percent were achieved. The beam pointing directions ranged from 27 to 29 degrees from the normal to the aperture. Sidelobes of 15 dB or better were also obtained. 相似文献
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A millimetric array is described which employs dielectric radiating elements excited by means of a dielectric waveguide. The design of the array is developed using the method of effective dielectric constants and a simple array theory. Measurements performed on a nonresonant prototype demonstrate its feasibility and its potential for frequency-scanning applications. 相似文献
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采用MonteCarlo法分析了平板裂缝天线辐射缝的导纳误差。建立辐射缝导纳误差的概率模型,将波导和裂缝的结构参数误差看作在某误差范围内服从正态分布的随机变量。对这些变量进行抽样计算,得到各个结构参数误差对谐振频率和谐振电导的影响,其中缝隙长度和偏置的误差对谐振电导和谐振频率的影响较大,波导窄边和壁厚误差产生的影响较小。根据计算结果调整各结构参数的误差范围,使它们对谐振频率和谐振电导的影响程度接近,在此基础上分析了同时存在这些误差项时对谐振频率和谐振电导的影响,由此提出满足导纳提取精度要求的加工误差指标。最后用Ansoft HFSS软件仿真验证了该方法的正确性。 相似文献
18.
The method of induced magnetomotive forces is used for solving the problem of distribution of equivalent magnetic currents
in an antenna-waveguide structure of the “two-slot resonant diaphragm—rectangular resonator—radiating slot” type on the end
face of a semi-infinite rectangular waveguide. The numerical and experimental investigations of this system are performed
and the plotted electrodynamic characteristics are presented.
Original Russian Text ? M. V. Nesterenko, V. A. Katritch, 2007, published in Izvestiya VUZ. Radioelektronika, 2007, Vol. 50,
No. 4, pp. 68–76. 相似文献
19.
A set of theoretical design equations for a slot array fed by nonradiating dielectric (NRD) waveguide is developed. Mutual coupling between the slots cut into one of the metal walls of the waveguide is taken into consideration for a design that can have a predetermined radiation pattern. The theoretical development follows that of Elliott. 相似文献