共查询到20条相似文献,搜索用时 0 毫秒
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A theoretical formulation for the input impedance of an overmoded coaxial probe fed coaxial waveguide has been derived in terms of the geometrical variables, the modal field solutions, and the probe excitation current distribution. The formulation includes higher order mode propagation, a variable probe length, and general coaxial terminations in the secondary waveguide. The model compares well with experimental data derived from a structure supporting three propagating modes. 相似文献
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A simple transmission line feed model is presented for microstrip antennas in a two-sided structure coupling through a coaxial probe. The parameters of the model are extracted directly from the feed structure. The validity of the feed model combined with the recently developed transmission line model of microstrip antennas is verified by measurement.<> 相似文献
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Dyadic Green's functions for determining the electric and magnetic fields in a cylindrical waveguide due to a radially directed infinitesimally short electric dipole are derived. The waveguide is shorted at one end and terminated at a perfectly matched load at the other. Both TE and TM modes are considered. Based on these dyadic Green's functions, the input impedance of a coaxial line fed probe in front of the plunger is derived. The formula is expressed in a closed form. Excellent agreement between theoretical results and experimental data for exciting the TE11 mode in the X band for various probe positions is observed 相似文献
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A closed-form equation for the impedance transformation of an arbitrarily complex load, using a hyperbolic cosine-squared tapered transmission line, is presented. Design charts are also given. A numerical example is considered and results indicate a tremendous reduction in size, in comparison to other forms of lines, when hyperbolic cosine-squared lines are employed to match a large complex impedance to a real 50 Ω impedance. 相似文献
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Through the use of a perturbation approach, explicit expressions are derived for the changes in the electromagnetic field structure that occur when a transverse electromagnetic (TEM) mode on a coaxial transmission line enters a bend in the line. All of these changes are evaluated to at least first order in the inverse of the radius of curvature of the first nonvanishing correction term of the propagation constant (which is found to be of second order). Graphical results for the variation of the propagation constant as a function of curvature and other parameters characteristic of the coaxial line are presented 相似文献
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《Microwave Theory and Techniques》1993,41(1):53-61
A numerical analysis of two-conductor transmission line with a rectangular notch in the dielectric between the strips is presented. Three media integral equations are derived and solved for the charge distributions. The decoupling between such two-conductor coupled microstrip transmission lines is investigated for asymmetric conductors. It is found that the coupling between two conducting lines can be reduced significantly by removing dielectric material between the lines which has a rectangular shape. For best decoupling, the width should be as wide as possible between the conducting lines but the depth should have an optimum somewhere in the base dielectric substrate 相似文献
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The transition from a coaxial to shielded microstrip line is analyzed by applying a rigorous mode-matching technique. The symmetry axes of the two transmission lines are assumed to be parallel, while the relative position of the coaxial line center conductor with respect to the microstrip line is taken to be arbitrary. The fields inside the shielded microstrip line are expanded in terms of the normal hybrid modes, while in describing the fields inside the coaxial line the transverse electric and magnetic modes are utilized. Both propagating and evanescent modes are taken into account in each transmission line. A modified mode-matching procedure is used on the junction plane of the two transmission lines to formulate the corresponding discontinuity problem. The mode-matching equations are solved by applying projection techniques. Numerical stability and computational efficiency are achieved in determining the scattering parameters of the coaxial to microstrip line transitions. Numerical results are computed and presented for several coaxial-to-microstrip-line transition geometries 相似文献
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Optimization of transient feeding to parallel-plate transmission lines from coaxial line 总被引:4,自引:0,他引:4
Tian Chunming Wang Jianguo Meng Fenxia Zhang Maoyu Ge Debiao 《电子科学学刊(英文版)》2001,18(3):281-284
The transient feeding to parallel-plate transmission lines from coaxial line is optimized by using the Finite-Difference Time-Domain (FDTD) method and a simple FDTD feed model. Observing the reflected voltages, this letter presents the optimal feeding position and ratio of width to height for a given input impedance of the coaxial line. 相似文献
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A simple full-wave method for analysing rectangular microstrip antennas is presented. The problem of voltage term calculation is elucidated in the case of the microstripline-fed antenna. A new model for calculating the voltage term is proposed and compared to the other two models taken from the literature.<> 相似文献
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Ma Xikui 《电子科学学刊(英文版)》1987,4(2):155-160
The field matching method is used to calculate the capacitance of coaxial rectangular strip transmission line. This method
is simple, can be used conveniently and the magnitude of error can be effectively controlled. 相似文献
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In this paper, a new analysis for a double step microstrip discontinuity is presented by using generalized transmission line equations . The new analysis is based on a new concept of a finite-length transmission line integrated with its double step discontinuity so that the double step discontinuity is regarded as a finite-length nonuniform transmission line and the generalized equations could be directly implemented. Since the generalized equation coefficients are determined by dynamic numerical methods and the coefficients are invariant with the line excitation and load, the equations are dynamic rather than TEM. The interested discoveries are that the generalized equations for the whole double step structure or a partial double step structure can give us the same results and the generalized equations have broadband frequency characteristics. For the double step structure used in this paper for the analysis, the S-parameters for a frequency band from 0.5 GHz to 10 GHz can be well calculated by using only two separately generalized equations at frequency of 3 GHz and 8 GHz. 相似文献
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A probabilistic model of a multisection transmission line with a random characteristic impedance is developed. The average value of the voltage at the end of the random line is estimated from an equivalent homogeneous line, which depends on the mean values of the characteristic impedance and admittance distributions 相似文献
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《Electronics letters》1969,5(2):33-35
An approximation technique is used to calculate numerically the input impedance of a short antenna immersed in a warm plasma driven from a coaxial air line. The effect of the gap configuration is observed to be significant on the antenna reactance only. 相似文献
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A novel compact left-handed (LH) microstrip transmission line is presented. To establish a negative permeability and permittivity, the transmission line is loaded with step impedance resonators (SIRs) and an array of thin wires on dual-layer architecture. Compared to existing LH structures, which incorporate conventional split ring resonators (SRRs), the proposed structure is three times smaller in size whilst achieving the same performance. To illustrate the electromagnetic properties of the metamaterial, both analytical and full wave analysis were performed and utilized to determine the effective electromagnetic parameters of the proposed structures. The experimental results show that a microstrip line periodically loaded with SIR only produces a rejection of ?6?dB at a resonant frequency of 5.50?GHz. The results also indicate a pass-band response for a left-handed microstrip line (LHML) constructed from SIR and thin wire arrays at the same resonant frequency. 相似文献
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The Green's function is formed for the warm-plasma region surrounding an antenna driven from a coaxial air-filled transmission line, and hence the current distribution and input admittance of three types of antenna having this feed system are computed. Comparison is made between the antenna characteristics when driven in this fashion and by an idealised delta gap. 相似文献
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A quadrature hybrid is presented which is entirely composed of lengths of transmission line of characteristic impedance equal to that of the system in which it is used. It is useable over a 10% bandwidth centred on its nominal frequency. Its theoretical frequency responses over this band are presented. 相似文献