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1.
An analysis is presented of the characteristics of a broad wall radiating slot, offset from the center line and tilted with respect to the longitudinal axis of a rectangular waveguide. Pertinent integral equations are developed, taking into account finite wall thickness, and are solved for the slot aperture E -field using the method of moments. Compound slot characteristics are then deduced, including resonant length and dominant mode scattering. Numerical results for the scattering from resonant slots are presented over a range of offsets, tilt angles, frequencies and waveguide dimensions. For resonant compound slots, offset and tilt are shown to control the aperture electric-field amplitude with a phase variability of 360°. The results have significant applications in the design of compound slot arrays 相似文献
2.
An analysis of a slot-coupled T-junction consisting of a circular to rectangular waveguide is presented. The Galerkin method of moments with entire domain sinusoidal basis functions is used to solve the slot aperture electric field integral equations taking into account finite wall thickness. The slot coupler characteristics are deduced, including resonant length and dominant mode scattering. The theoretical results on the magnitude of the s-parameters are compared with experimental results. The effect of the variation of diameter of the circular waveguide as well as the width of the slot on the resonant length of the slot is also studied. 相似文献
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Resonant length of longitudinal slots and validity of circuit representation: Theory and experiment 总被引:4,自引:0,他引:4
Pertinent theory for the design of longitudinal slot arrays is reviewed and its dependence on the dominant mode scattering off a single slot is pinpointed. The critical need to know resonant length versus slot offset is emphasized and the desirability of determining this information theoretically rather than experimentally is argued. Then method of moments solutions are used to calculate resonant length versus slot offset for given waveguide dimensions and frequency. These theoretical results are compared to new, carefully obtained experimental data. Agreement is found to be so good, it is concluded that one can dispense with the costly gathering of experimental input data when designing longitudinal slot arrays fed by standard rectangular waveguide. A critical look is taken at the validity of representing the longitudinal slot as a shunt element on an equivalent transmission line. This assumption is found to be more and more questionable as theb dimension is reduced. For quarter-height guide, an alternate design procedure is suggested as being more accurate. 相似文献
4.
Wu Ren Ben-Qing Gao Zheng-Hui Xue Wei-Ming Li Bo Liu 《Antennas and Propagation, IEEE Transactions on》2004,52(9):2436-2444
A rigorous analysis of the resonant characteristics for a broad wall waveguide slot by using the finite-difference time-domain method is presented. Four types of slots including a radiating longitudinal shunt slot, a longitudinal/transverse coupling slot, a centered-inclined coupling slot and a compound coupling slot are analyzed. Lots of slot characteristics such as the resonant length, scattering parameters and normalized admittance in different offsets, tilt angles or slot sizes are obtained. Because the shape of slots is a rectangle with rounded ends in practical fabrication, an accurate modeling and computation for the slots with rounded ends is implemented, and the resonant lengths calculated coincide well with the Stegen's measured data and method of moments results. From these computed results, it is found that all the resonant characteristics of the slots with rounded ends are significantly different from those with normal rectangular ends. 相似文献
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Analysis of a centered-inclined waveguide slot coupler 总被引:5,自引:0,他引:5
Integral equations are developed for a centered-inclined coupling slot (including the effect of finite wall-thickness of the common broad-wall) and the slot-aperture electric intensity field is found using the method of moments. Numerical results for resonant length, backscattered wave amplitude, and phase variation off-resonance are presented over a range of values of the waveguide b dimension, wall thickness, slot width, and frequency. It is shown that the resonant length is relatively insensitive to slot tilt, &thetas;, for a standard-height X -band waveguide, whereas its dependence on &thetas; is significant for reduced-height waveguides. The phase variation of scattered TE10 waves in both waveguides off-resonance is less for wider slots and smaller b dimensions. Shunt-series coupling slots exhibit greater phase variation off resonance when compared to a centred-inclined coupling slot. Also, the former has a longer resonant length for a smaller b dimension and for a wider slot. Thus the centred-inclined slot coupler possesses superior characteristics. The higher-order mode coupling between a centred-inclined slot coupler and a pair of straddling radiating slots in the branch waveguide is significant 相似文献
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The design of small slot arrays 总被引:13,自引:0,他引:13
The differences in mutual coupling for a central slot and a peripheral slot cannot be ignored in small arrays if good patterns and impedance are to be obtained. A theory has been developed whereby the length and offset of every slot in the array can be determined, in the presence of mutual coupling, for a specified aperture distribution and impedance match. The theory enlarges on Stevenson's method, and uses a modified form of Booker's relation based on Babinet's principle to treat nonresonant longitudinal shunt slots in the broad wall of a rectangular waveguide. A general relation between slot voltage and mode voltage is developed, and then formulas are derived for the active, self-, and mutual admittances among slots. These formulas result in a design procedure. Analogous treatments of inclined series slots in rectangular guide and of strip-line-fed slots are possible. Comparison between various experiments and the theory is presented. Tests of the theory include the resonant length of a zero offset slot, resonant conductance versus offset and resonant conductance versus frequency for a single slot, and self- and mutual admittances for two staggered slots. The design and performance of a two-by-four longitudinal shunt slot array is also described. 相似文献
9.
A resonant coupling slot cut in the common broad wall of two crossed rectangular waveguides is analyzed. The slot is offset from the center line and tilted with respect to the longitudinal axis of the main waveguide, whereas it is centered-tiled in the branch waveguide. It is shown that the slot offset and tilt control the branch waveguide excitation amplitude with a phase variability of 360°. Pertinent integral equations are developed, taking into account finite wall thickness. The integral equations are solved for the slot aperture electric field using the method of moments. Dominant mode scattering by the slot in both waveguides is obtained 相似文献
10.
本文首先研究了多区域时域伪谱(MPSTD)算法应用于波导问题分析时的时域激励源设置方法。然后在此基础上,将MPSTD算法应用于矩形波导宽壁复合缝隙耦合器的分析。针对X波段半高波导,得出了耦合缝隙在不同高度、不同偏置和不同倾斜角度下的谐振长度和散射参量特性。仿真结果表明,将MPSTD算法应用于波导缝隙耦合器的分析,具有较高的计算效率和计算精度。同时该问题的MPSTD分析也拓展了MPSTD算法的应用领域,为准确、快速分析复杂波导问题的宽频时域特性提供了一种思路。 相似文献
11.
Numerical analysis is presented for the characteristic parameters of centered-inclined coupling slot in rectangular waveguides,taking into account the transverse distribution of the electric field across the slot aperture.Integral equations are formulated based on dyadic Green's function theories and solved using the method of moments.Trigonometric basis functions are adopted.It is found that the method will converge with up to ten basis functions.The characteristic parameters can be easily obtained for different slot sizes.Resonant length and resonant resistance of the coupling slots are calculated.It is shown that the calculated results have very high accuracy,compared with simulated results obtained from commercial software.Therefore,it can be effectively applied in the synthesis of antenna arrays.Effects of the transverse distribution on calculating resonant parameters of the coupling slot are also analyzed.The results show that if the transverse distribution of the electric field is neglected,the calculated error tends to become larger when the slot gets wider or thinner. 相似文献
12.
Transverse electric (TE) and transverse magnetic (TM) scattering from dielectric-filled, cavity-backed apertures in two-dimensional bodies are treated using the method of moments technique to solve a set of combined-field integral equations for the equivalent induced electric and magnetic currents on the exterior of the scattering body and on the associated aperture. Results are presented for the backscatter radar cross section (RCS) versus the electrical size of the scatterer for two different dielectric-filled cavity-backed geometries. The first geometry is a circular cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the cylinder is dielectric filled and is also of circular cross section. The two cylinders (external and internal) are of different radii and their respective longitudinal axes are parallel but not collocated. The second is a square cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the square cylinder is dielectric-filled and is also of square cross section 相似文献
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Forooraghi K. Kildal P.-S. Rengarajan S.R. 《Antennas and Propagation, IEEE Transactions on》1993,41(4):422-428
An efficient method of computing resonant length and admittance characteristics of an isolated broad-wall shunt slot radiating between baffles of finite height is presented. The outer three-dimensional (3D) field problem associated with this geometry is reduced to a two-dimensional (2D) one via a Fourier transformation with respect to the longitudinal z direction. For each value of the longitudinal wave number k z an integral equation is solved for the E field in the mouth of the plates using the method of moments. This procedure is repeated for several discrete values of k z, to obtain a spectrum of 2D solutions which are then inverse-transformed to construct the 3D solution in the spatial domain for the exterior baffle region and the half space. The slot aperture field is determined by the conventional moment method solution to the integral equation that enforces the continuity of the H field across the slot. Scattering properties of the slot are then deduced. Numerical results for the resonant length and resonant conductance are presented. Computer results are found to be in good agreement with experimentally measured data 相似文献
15.
The admittance properties and the resonant length of an inclined slot in the narrow wall of a rectangular waveguide have been investigated. The depth of cut of the slot in the broad walls of the waveguide has been taken into account. The internal power storage in evanescent modes in the waveguide, neglected in previous studies, is included. Theoretical results for the variations of conductance and resonant length with the angle of inclination of slots are presented. Through comparisons of the calculated results with previously available experimental data, the importance of the inclusion of the waveguide internal power storage is emphasized 相似文献
16.
Raju G.S.N. Chakraborty A. Das B.N. 《Antennas and Propagation, IEEE Transactions on》1990,38(1):24-29
Investigations of the resonant length and admittance of inclined slots in the narrow wall of a rectangular waveguide that are sufficiently wide for applications involving high power handling capacity are presented. For high accuracy, the integrals appearing in the expression for the self-reaction are evaluated numerically instead of attempting to derive closed-form expressions, which are applicable only to thin slots. Numerical data on the variation of resonant length with slot width and also on the variation of real and imaginary parts of the admittance with 2L /λ as well as frequency for wide slots are presented. Comparison between theory and experimental results is presented for a slot with a width of 1.6 mm and a depth of cut in both the broad walls of 2.23 mm 相似文献
17.
Formulas for the field components of the TEpq, mode and the dominant mode TE11 in a sectoral waveguide are given. Using the equivalence principle, the electric field distribution on the aperture surface of a narrow longitudinal slot cut in the curved broad wall of a sectoral waveguide is solved by the moment method (Galerkin's method). Important results such as the scattering parameters, the equivalent shunt admittance, and the resonant conductance and length are studied. The method used in this paper has good precision and has been adopted in the design of a linear slot array 相似文献
18.
Analysis of longitudinal slots in rectangular waveguides 总被引:4,自引:0,他引:4
An accurate computation of the admittance characteristics of longitudinal shunt slots in a rectangular waveguide is presented. A moment method with entire basis functions is used for solving the electric field in the slot. The waveguide wall thickness is accounted for by introducing higher order waveguide modes in the short waveguide connecting the inner and outer regions. Particular attention is given to the resonant length of the slot, which is a critical parameter in the design of waveguide slot array antennas. Computed resonant lengths compare very well with measured results. 相似文献
19.
A method to determine the admittance and resonant length of an inclined slot in the narrow wall of a rectangular waveguide is presented. An expression for the admittance of the slot is derived using an angular spectrum of planewaves and the discontinuity in modal current. When the depth of cut in the top and bottom wall is assumed to be zero, the expression for resonant conductance found by the present method is exactly the same as that obtained by Stevenson. Comparison between the theoretical and experimental results on the variation of resonant conductance with angle of inclination of slots for a fixed depth of cut of 3.5 mm is presented. 相似文献
20.
The input admittance of the rectangular cavity-backed slot antenna is investigated. The slot is assumed narrow so that the voltage distribution in its aperture is sinusoidal. Equations which represent the input admittance of this slot, backed by a rectangular cavity in which a single propagating wave is assumed to exist, are given. Calculations based on these representations are compared to available measured data. As the depth of the cavity increased the resonant frequency decreased and the bandwidth became narrower. Input admittance curves as a function of electrical slot length are also presented for several size cavities. 相似文献