摘要:

A new method for analyzing frequency-dependent transmission line systems with nonlinear terminations is presented. The generalized scattering matrix formulation is used as the foundation for the time domain iteration scheme. Compared to the admittance matrix approach proposed in a previous paper, it has the advantage of shorter impulse response which leads to smaller computer memory requirement and faster computation time. Examples of a microstrip line loaded with nonlinear elements are given to illustrate the efficiency of this method.

ISSN:0920-5071    

DOI:10.1163/156939389X00430

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We consider the following electromagnetic sounding configuration: A time harmonic magnetic transmitter is placed on the surface of earth having a depth-dependent conductivity structure. The total magnetic field is measured at a fixed point with a finite number of frequencies. A numerical method is given for the recovery of the incident field directly by these measurements. The method is based on the use of the dispersion relation.

ISSN:0920-5071    

DOI:10.1163/156939389X00449

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A general description of the power flow in real multimode waveguides is presented. In the time domain, an integrodifferential equation is derived and solved in three ways. For a given input power excitation, the derived approximate techniques make it possible to calculate an impulse response of the waveguide. A general property of the coupling function, describing arbitrary stochastic mode conversion causes, is given and in the case of microbendings and small scatterers, the coupling function is specified. For waveguides showing some mode degeneracy, the integrodifferential equation is modified and a transformed coupling function is described.

ISSN:0920-5071    

DOI:10.1163/156939389X00458

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Radar cross section (RCS) reduction by absorber covering is experimentally studied by employing microwave diversity imaging. Experimental results show that broadband absorber covering is not effective at reducing the co-polarized (the transmitting andreceiving antennas have opposite sense of circular polarization) RCS of a plate when theincident wave approximates the edge-on direction but is effective at reducing the cross-polarized (both the transmitting and receiving antennas have the same sense of circularpolarization) RCS for all incident directions. The surface current absorber covering iseffective at reducing the non-specular energy and multiple bounces regardless of the polarization status of the measurement.

ISSN:0920-5071    

DOI:10.1163/156939389X00467

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

There is a need for a solution to the problem of wave scattering from rough surfaces that is accurate when both the classical field perturbation and Kirchhoff approximations are not. In previous work it was shown numerically that the phase perturbation reflection and backscattering coefficients reduce to those of field perturbation theory and the Kirchhoff approximation in the appropriate limits; however, for cases when the classical solutions did not apply, the accuracy of the phase perturbation results could not be determined. In this paper we examine the validity of the phase perturbation technique for a region in parameter space when the two classical solutions fail. Numerical results for the bistatic scattering cross section are compared with exact numerical results for one-dimensional surfaces having a Gaussian roughness spectrum and satisfying a Dirichlet boundary condition. It is found that in the region considered the phase perturbation results agree with the exact results over all scattered angles, except low grazing angles, for a fixed angle of incidence. Furthermore, in many cases it is found that exchanging incident and scattered angles in the phase perturbation equations gives an alternate phase perturbation solution whose numerical results are in excellent agreement with exact results.

ISSN:0920-5071    

DOI:10.1163/156939389X00476

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Theoretically, a wave field may be represented by different superpositions of both discrete and continuous waves. This leads to the problem of physical actualization (separation, detection) of individual virtual-field components. The present work analyzes some procedures for virtual field actualization: using the results of angular spectrum measurements, applying the extended curvilinear antennas, by means of antennas focused at the virtual field, etc. Typical examples are presented to show that the virtual fields can be separated by means of physical devices: measurements of Huygens' sources with focused antennas and measurements of virtual fields related to wedge geometry and diffraction rays.

ISSN:0920-5071    

DOI:10.1163/156939389X00485

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A rigorous analysis of a circularly cylindrical resonator containing an axially magnetized stratified gyromagnetic medium is presented. The full-wave mode matching method is used. The field inside a cavity is expanded into series of transverse mode functions of a layered gyromagnetic parallel-plate line. An exemplary ferrite-air resonator is investigated numerically and experimentally showing good agreement of computed resonant frequencies with measured values.

ISSN:0920-5071    

DOI:10.1163/156939389X00494

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939389X00502

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor