共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper presents an analysis of radiation from a horn with a superquadric aperture, modeled using a cascade of superquadric waveguides. Electromagnetic fields within each waveguide are expressed in terms of a set of orthogonal modes derived from polynomial functions based on a Cartesian coordinate system. The scattering matrix at the horn aperture is obtained by calculating the scattering matrix at each of the waveguide junctions using mode matching, and cascading them appropriately. Radiation patterns corresponding to both x- and y-polarizations of the input excitation are then obtained by integrating the aperture field. The computed numerical results are validated by comparing them with the corresponding results obtained from measurements. 相似文献
2.
The result of Yee et al. (1968) for the parallel-plane TE10 -mode reflection coefficient, used in Jull's (1972) formulation for the reflection coefficient of a long E-plane sectoral horn, is replaced by the Boersma's (1974) corresponding result. At longer wavelengths, the expression that emerges displays a much better match with experiments than Jull's original expressions 相似文献
3.
A microwave transmitting antenna with omnidirectional pattern in the horizontal plane is described which consists of six horn radiators and six plane reflectors arranged in a hexagonal configuration. Each reflector illuminates an azimuthal sector of approximately 60°. If therefore, a sector-shaped horizontal pattern is required, less than six reflectors need to be provided. 相似文献
4.
The complex reflection coefficient of a longE -plane sectoral horn is derived using the geometrical theory of diffraction. Single diffraction alone is shown to be sufficient to describe the contribution from theE (widely separated) edges, while singly and doubly diffracted fields from theH edges are included by using an open waveguide result derived elsewhere. A relatively uncomplicated expression is obtained for the complex reflection coefficient of the horn which agrees well with experiment for horns with slant wall lengths greater than about3frac{1}{2} guide wavelengths. 相似文献
5.
The possible existence of blind spots, due to forced aperture resonances, is demonstrated theoretically and experimentally at 14 GHz in rectangular grid arrays of tapered rectangular horn elements with oversized (overmoded) apertures. The dominant contributor to these blind spots is the resonance of the equivalent transverse magnetic (TM_12 ) waveguide mode. The numerical results based upon our approximate methods of formulation and solution of the array boundary value problem agree well with experiments. A method for eliminating the blind spots by proper taper design is presented and experimentally verified. The analytical methods used in this work could possibly be extended to conical horus and other tapered-structure arrays as well as other periodic grid geometries. New simple and accurate formulas for the zeros of Bessel and Legendre functions and their derivatives are obtained as a result of this analysis. 相似文献
6.
A novel design of plasma torch is described, in which the flame cross-section has a major axis five times that of the minor axis. The ion number density has been measured and compared with that of the conventional torch with a flame of circular cross-section. 相似文献
7.
Knop C. Yuk-Bun Cheng Ostertag E. 《Antennas and Propagation, IEEE Transactions on》1986,34(9):1092-1098
The electromagnetic fields propagating up a cone having an arbitrary wall impedance are found using an asymptotic solution. Three special cases are then considered: the smooth-metal wall, the corrugated wall, and the metal wall with a lossy-dielectric lining. The last case, in the form of an absorber-lining is then shown to behave like a corrugated horn since it too provides a highly taperedE -plane andH -plane aperture distribution. Furthermore, it does this over a much larger bandwidth, over 3:1, with negligible gain drop. 相似文献
8.
In this paper a small aperture multimode horn is analysed by full-wave method and the coupling efficiency to Gaussian fundamental mode is calculated. The coupling efficiency of exceeding 0.98 is obtained over 4 GHz bandwidth. This horn may be used to connect waveguide with quasi-optical element in millimeter wave system and also may be used as an element in imaging array. 相似文献
9.
The response of various types of dielectrically loaded radiators to a time-harmonic excitation is analyzed, by employing an integral-equation formulation in conjunction with an entire-domain Galerkin technique. Coupled integral equations are derived in the frequency domain. These are written in terms of the conductivity currents or/and the electric fields developed on the conducting surfaces or/and inside the dielectric materials, respectively. They are solved via the method-of-moments technique. In particular, an entire-domain Galerkin technique is employed, and proves very efficient, when rather specific geometries are considered and appropriate “intelligent” basis-function sets are chosen, accelerating the convergence of the method. To prove this claim, three representative antenna structures, of significant practical use, corresponding to the three types of geometries (cylindrical, spherical, and planar), are solved in the resonance region. Parallelization of the developed sequential code is employed, in order to extend the use of Galerkin technique to electrically large structures. The validity of the proposed method is checked, and numerical results are presented for several cases 相似文献
10.
11.
复射线作为一种有效的数值计算方法得到了较广泛的研究和应用。但,复射线的复源点模型脱物理现实。而将复射线表示为一平面口径的辐射场,从而为复射线的发生提供了一种现实的物理模型--平面口径辐射。在此基础上,对复射线的一些相关的问题进行了比较深入的讨论。 相似文献
12.
A.K. Govil 《Microelectronics Reliability》1982,22(4):685-688
In this paper, a complex system comprised of two types of component is considered. Type I consists of N components connected in series, whereas type II consists of components connected in standby redundancy. It is assumed that a standby component may also fail in its shelf-life. Further, the system experiences two modes of failure—the first due to change in performance characteristics and the second due to a common cause. The availability of such a system is investigated using supplementary variable techniques and Laplace transforms. Finally, a number of interesting particular cases are discussed. 相似文献
13.
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
14.
A step horn structure is presented that yields about 90% aperture efficiency with low cross-polar radiation. It is found that for obtaining high aperture efficiency, the horn aperture should consist of only the TE/sub z/ type of modes in appropriate amplitudes and phases. The desired TE/sub z/ modes are produced using multiple steps in the horn walls. The distances between the steps are critical to suppress the undesired TM/sub z/ modes. Radiation characteristics of high efficiency circular and square horns are presented and potential applications of such high efficiency horns are discussed. 相似文献
15.
An exact analysis of double-tuned circular disc resonators/radiators is described. This method is based on the Hankel transform domain analysis and is numerically quite efficient. Several numerical examples are compared with available experimental data. 相似文献
16.
Analysis of electric quadrupole radiation in the time domain: application to large-current radiators
In this paper, the fields created by a hertzian electric quadrupole fed by a non-sinusoidal signal are analysed in the time domain. The results are compared with those obtained for an electric dipole and are applied to the study of the field created by the practical antenna, the large-current radiator. 相似文献
17.
B. M. Levin 《Journal of Communications Technology and Electronics》2011,56(1):27-34
The mutual effect of electric dipoles that are close to each other is analyzed in the near-field zone. The input impedances, currents and fields of the radiators are calculated. The method for the calculation of the system of two radiators is based on the theory of folded dipoles. The fields of application of the closely lying radiators are presented. 相似文献
18.
Domain decomposition FDTD algorithm for the analysis of a new type of E-plane sectorial horn with aperture field distribution optimization 总被引:6,自引:0,他引:6
Feng Xu Wei Hong 《Antennas and Propagation, IEEE Transactions on》2004,52(2):426-434
In this paper, a universal and efficient approach of domain decomposition finite-difference time-domain FDTD (DD-FDTD) is presented for the analysis of a new type of horn antenna-E-plane sectorial horn with field amplitude taper and phase correction in the aperture. The power fed into the horn is redistributed to achieve the optimal field amplitude distribution in the aperture, and meanwhile the field phase is corrected by metal lens. Compared with conventional E-plane sectorial horns, the new horn antenna takes the advantages of low sidelobe level, short physical length and wide flare angle etc. Moreover, the most important property of this horn is the weak coupling with each other when it is used as the element of a phased array antenna. The field analysis of such a horn antenna is an extremely complicated three-dimensional EM boundary value problem. The domain decomposition FDTD method is presented in this paper to break through the drawback. The whole horn is decomposed into several subdomains and the meshes are created in local coordinates. In the iteration procedure of FDTD, the data are exchanged between adjacent subdomains with overlapped meshes. The aperture field distribution, voltage standing-wave ratio and pattern calculated by the DD-FDTD method are in good agreement with the experimental data. 相似文献
19.
Analytical form of EM fields radiated by circular aperture antennas of various current distributions
~~Analytical form of EM fields radiated by circular aperture antennas of various current distributions[1] Schelkunoff S. A., Advanced Antenna Theory, John Wiley &Sons, 1952.
[2] E|liott R.S., Antenna Theory and Design, Prentice-Hall, Engie-wood Cliffs, N J, 1981.
[3] R.W.P. King and G.S. Smith, Antennas in Matter: fundamen-tals, Theory and Applications, MIT Press, Cambirdge, MA,1981.
[4] W.L. Stutzman and G.A. Thiele, Antenna Theory and Desigrn,John Wiley & S… 相似文献