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1.
In this paper we use a hybrid method to calculate the admittance of a longitudinal slot (of finite length) in a rectangular waveguide, when the slot radiates into a cylindrical outer structure of arbitrary finite cross section. The analysis takes advantage of a Fourier transformation along the cylinder axis, by which the computational effort is drastically reduced. The harmonic spectral currents on the structure are expanded in subsectional triangular basis functions and determined using an electric field integral equation (EFIE) and the moment method. These currents and the corresponding fields are inverse Fourier transformed and matched over the slot to the fields inside the waveguide by an additional moment method approach using entire domain basis functions for the slot field. The calculated slot admittance has good accuracy when compared with measurements on a chosen geometry 相似文献
2.
The admittance of a half-wavelength slot antenna in a two-layer lossy plasma is shown to be greatly affected by moderate electron temperatures (T_{e} leq 1 eV ) when the plasma is overdense. The effects of slot width and electron collision frequency upon the slot admittance also are investigated. 相似文献
3.
Theory and experiment are compared for the admittance presented to a rectangular waveguide which terminates at an arbitrary angle in the surface of a conducting cylinder. Two methods are described for calculating the admittance: a single-mode approximation from the modal solution and an alternative asymptotic solution. Using these methods, the effect of aperture orientation on admittance, and the results obtained are compared with the experiment. The single-mode approximation is in good agreement with experimental results for the case when the input waveguide supports the TE10 mode only. The accuracy of the approximate formula for waveguide admittance was also verified. The admittance is shown to be weakly dependent on aperture orientation for moderately large cylinders 相似文献
4.
A slot covered by a stratified plasma is assumed to radiate into a wide waveguide instead of free space. The slot admittance approximates the free space admittance of the slot for waveguide diameters exceeding 6 to10lambda . For thick plasma layers the computed slot admittance checks with earlier admittance calculations for a laterally unbounded plasma. When approximating a plasma profile of a typical hypersonic re-entry, a multilayer plasma model in a wide waveguide appears to provide a more accurate slot admittance than a single-layer approximation in a laterally unbounded geometry. 相似文献
5.
Moo-Ha Song Jong-Myung Woo 《Electronics letters》2003,39(5):417-419
A highly miniaturised rectangular microstrip patch antenna using deformation of the patch structure has been designed and fabricated at a frequency of 1.575 GHz (GPS). The fabricated antenna has a patch with an overall rectangular shape and depressed at its four corners (corner depressed microstrip patch antenna, CDMPA). In the linear polarisation, at a fixed rate of 1.2 of width/length (W/L), the CDMPA (53/spl times/63.6 mm) is reduced to 43.9% of the general plane type microstrip patch antenna (MPA, 80/spl times/96 mm) in patch size. The gain is 4.3 dBd which is lower than that of the general MPA (8 dBd) by 3.7 dB. In the circular polarisation, the patch size of the CDMPA (54.2/spl times/61.5 mm) is reduced to 52.8% of that of the MPA (76/spl times/83 mm). The axial ratio (AR) and axial ratio band width (ARBW) within 2 dB are 1.5 dB and 20 MHz (1.27%), respectively. The gain is 2.5 dBd, which is lower than that (4.2 dBd) of the general MPA by 1.7 dB. 相似文献
6.
This paper presents a novel design for a dual-band coplanar waveguide-fed-slot antenna that operates at 27GHz and 39GHz. Matching this antenna at the two widely separated frequencies is achieved using a special matching network of slot antennas. Experimental and numerical results are presented for the return loss and radiation patterns of this antenna. 相似文献
7.
Tzung-Fang Huang Shih-Wen Lu Powen Hsu 《Antennas and Propagation, IEEE Transactions on》1999,47(10):1560-1565
A method for analyzing and designing the slot antenna array excited by a coplanar waveguide (CPW) is presented. The slots are etched on the conducting plane of the CPW and placed in the direction perpendicular to the transmission line. Moment-method analysis and matrix-pencil approach are adopted to calculate the scattering parameters and hence the self-admittance of each slot. The mutual admittances between the slots are calculated from the formulas derived for the complementary strip dipoles based on the reciprocity theorem and via Booker's relation. Then the transmission line theory is used to calculate the input impedance of the array, and an iterative process is employed to obtain a matched design for a desired slot-voltage distribution. A four-element slot array is fabricated and measured using this design procedure. Calculated results are in good agreement with measurements 相似文献
8.
The mutual coupling between groundplane slots in aperture-coupled patch antennas on cylindrical structures is calculated using a moment method in the Fourier domain. By separating the three-dimensional (3D) problem into a spectrum of two-dimensional (2D) problems an efficient calculation of the admittance is possible. To increase the accuracy in the mutual admittance calculation, an asymptotic extraction technique is used. Several cases of antenna geometry are investigated and comparison is made to measurements. The method used allows for efficient and accurate analysis of dual polarized aperture-coupled patches placed on general cylindrical structures, as in the case of base-station antenna arrays for mobile communications. 相似文献
9.
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
10.
The rectangular cavity backed slot is excited by a current source connected across its center. The longitudinal voltage variation across the slot is obtained from the variational solution of an integral equation. For shallow and narrow cavities the slot appears inductive and the voltage is rapidly attenuated along the slots. The slot may resonate for deeper and/or wider cavities, when the voltage along the slot is approximated by a half-cycle of a sine wave. The resonant cavity depth and the antenna bandwidth are examined for various cavity and Slot parameters. Dielectric cavity loading is shown to decrease both the resonant cavity depth and the antenna bandwidth. 相似文献
11.
The admittance calculation for a narrow slot in the conducting shield of a multiconductor transmission line (MTL) is presented. An approximate calculation is given for the admittance seen looking into a slot in the shield of a multiconductor transmission line when a uniform magnetic current is placed over the slot. The calculation presented is approximate in that only the transmission line mode is used in the calculation. All higher-order waveguide modes are neglected. This allows the magnetic current to be replaced by a point voltage source at the slot location. The admittance calculation then corresponds to calculating the driving point admittance of a point voltage source located in the shield of an MTL 相似文献
12.
Equivalent-circuit representation and characteristics of a radiating cylinder driven through a circumferential slot 总被引:1,自引:0,他引:1
The problem of an infinitely long coaxial cylinder with a single circumferential slot in the sheath is investigated analytically. When the slot width is small compared with the radius of the outer cylinder, an exact integral equation for the aperture field is formulated and subsequently solved by a quasi-static technique. Equivalent circuit representation of the coupling between the outside antenna and the inside coaxial line is obtained in closed form. Due to the highly localized nature of the coupling, the result thus obtained is applicable to finite cylindrical antenna with multiple feed slots. 相似文献
13.
Einarsson O. Sleator F. Uslenghi P. 《Antennas and Propagation, IEEE Transactions on》1975,23(1):28-36
The synthesis of a prescribed far-field pattern by means of a radiating slot in a perfectly conducting infinite circular cylinder is considered. The narrow circumferential slot and the infinite axial slot are studied in detail. In either case, the problem is to find the distribution of the electromagnetic field in the aperture that yields a radiation pattern that is the best mean-square approximation to a given pattern, under certain constraints. Various quality factors for cylindrical modes are discussed, and a detailed comparison with the synthesis problem for a planar aperture is performed. It turns out that Rhodes' synthesis method has no equivalent in the cylindrical case, and that the best admissible mean-square approximation to a given pattern may be a very poor approximation in amplitude. However, an iteration scheme is developed in which the phase approximation is sacrificed for the sake of substantially improving the amplitude approximation. Numerical results based on such a scheme are displayed, for prescribed omnidirectional and sectoral patterns. 相似文献
14.
An experiment to determine the input admittance of a slot antenna after r.f. voltage breakdown outside the aperture has occurred is described. It is found that the conductance decreases and the susceptance increases with input-power level. 相似文献
15.
An analysis of a wide rectangular radiating slot excited by a microstrip line is described. Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture. The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function. The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique. The theoretical analysis is described and data are presented and compared with other theoretical and experimental results 相似文献
16.
Kildal P.-S. Rengarajan S. Moldsvor A. 《Antennas and Propagation, IEEE Transactions on》1996,44(8):1183-1192
This paper presents a powerful method for analysing antennas which can be considered principally two-dimensional (2-D) or cylindrical, except for some three-dimensional (3-D) physical or equivalent sources, e.g., dipoles or slots. It is shown by Fourier transform techniques that such antennas can be analyzed as 2-D problems with harmonic longitudinal field variation. The radiation pattern can often be determined directly from a finite set of such 2-D solutions, each one obtained by any method, e.g., the moment method. The mutual interaction between the cylindrical scatterer and the sources must be calculated to determine the exact current distribution on the sources and their impedances or admittances. This is facilitated by performing an inverse Fourier transform of an infinite spectrum of the numerical 2-D solutions followed by a moment method solution in the spatial domain to satisfy the boundary conditions on the 3-D equivalent sources themselves. The inverse Fourier transform is simplified by the use of asymptote extraction. The method is in itself a hybrid technique as one method is used to solve the harmonic 2-D problem, and the other to solve for the source currents 相似文献
17.
18.
The theoretical radiation resistance of an isolated slot ring resonator is expressed by means of an analytical formula. The result is deduced from the radiation resistance of an equivalent circular loop of the same size when Babinet's principle is applied. Results are compared with recent theoretical and experimental ones. 相似文献
19.
S. E. Bankov 《Journal of Communications Technology and Electronics》2017,62(11):1201-1208
The problem of radiation of the eigenmodes of an infinite 2D array of semi-infinite coupled slot lines is solved. An analytical solution for the electric field on conductors is found by the Wiener–Hopf method in the approximation of narrow conductors forming the slot lines. An algorithm of numerical implementation of this solution is developed. Expressions for elements of the scattering matrix of an infinite array are found. Dependences of the elements of the scattering matrix on frequency and the structure parameters are studied numerically. 相似文献