A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1...A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1B - （ωε）^-1γJ is given. The divergenceless and irrotational splitting of dyadic Dirac 8 function and Fourier transformation are used to directly obtain the divergenceless and irrotational component of spectral-domain dyadic Green＇s functions in chiral media. This method avoids using the dyadic Green＇s function eigenfunction expansion technique. The method given here can be generalized to a source-free region and an achiral case.展开更多
A new method for solving electromagnetic field boundary value problem is given.Byusing this method,the boundary value problem of the vector wave equation can be transformedinto the independent boundary value problem o...A new method for solving electromagnetic field boundary value problem is given.Byusing this method,the boundary value problem of the vector wave equation can be transformedinto the independent boundary value problem of scalar wave equations and the two additionalvector differential operations.All the dyadic Green’s functions got by eigenfunction expansionof the dyadic Green’s function can be got by this method easily and some of the dyadic Green’sfunctions for complex systems which are very difficult to get by the ordinary method have beengot by this new method.The dyadic Green’s function for a dielectric loaded cavity is one of thegiven examples.展开更多
This paper presents a method to derive the Dyadic Green’s Function(DGF)ofa loaded rectangular waveguide by using the image method.In the calculation of the DGF,we use the integral transformation and replace the multi...This paper presents a method to derive the Dyadic Green’s Function(DGF)ofa loaded rectangular waveguide by using the image method.In the calculation of the DGF,we use the integral transformation and replace the multi-infinite summation by a single one;thus it greatly simplifies the calculation and saves computer time.As an example of the DGF’sapplication,we give the moment method’s scattering field calculation of a metal sphere resting onthe broad wall of the loaded rectangular waveguide.Results of our calculations well agree withboth data of experiments performed in our laboratory and those are published.It is easy to seethat the method used in this paper can be expanded to other related waveguide problems.展开更多
Herein a novel Dyadic Green’s Function (DGF) is presented to calculate the field in ElectroMag-netic Compatibility (EMC) chamber. Due to the difficulty of simulating the whole chamber environment, the analysis combin...Herein a novel Dyadic Green’s Function (DGF) is presented to calculate the field in ElectroMag-netic Compatibility (EMC) chamber. Due to the difficulty of simulating the whole chamber environment, the analysis combines the DGF formulation and the FEM method, with the latter deals with the reflection from absorbers. With DGF formulation for infinite periodic array structures, this paper investigates electromagnetic field in chamber with truncated arrays. The reflection from the absorber serves as the virtual source contribut-ing to the total field. Hence the whole chamber field calculation can be separated from the work of absorber model set-up. Practically the field homogeneity test and Normal Site Attenuation (NSA) test are carried out to evaluate the chamber performance. Based on the method in this paper, the simulation results agree well with the test, and predict successfully the victim frequency points of the chamber.展开更多
Based on the dipole source method, all components of the Green＇s functions in spectral domain are restructured concisely by four basis functions, and in terms of the two-level discrete complex image method （DCIM） w...Based on the dipole source method, all components of the Green＇s functions in spectral domain are restructured concisely by four basis functions, and in terms of the two-level discrete complex image method （DCIM） with the high order Sommerfeld identities, an efficient algorithm for closed-form Green＇s functions in spatial domain in multilayered media is presented. This new work enjoys the advantages of the surface wave pole extraction directly carried out by the generalized integral path without troubles of that all components of Green＇s function in spectral domain should be reformed respectively in transmission line network analogy, and then the Green＇s functions for mixed-potential integral equation （MPIE） analysis in both near-field and far-field in multilayered media are obtained. In addition, the curl operator for coupled field in MPIE is avoided conveniently. It is especially applicable and useful to characterize the electromagnetic scattering by, and radiation in the presence of, the electrically large 3-D objects in multilayered media. The numerical results of the S-parameters of a microstrip periodic bandgap （PBG） filter, the radar cross section （RCS） of a large microstrip antenna array, the characteristics of scattering, and radiation from the three-dimensional （3-D） targets in multilayered media are obtained, to demonstrate better effectiveness and accuracy of this technique.展开更多
A recursive algorithm is adopted for the computation of dyadic Green＇s functions in three-dimensional stratified uniaxial anisotropic media with arbitrary number of layers. Three linear equation groups for computing ...A recursive algorithm is adopted for the computation of dyadic Green＇s functions in three-dimensional stratified uniaxial anisotropic media with arbitrary number of layers. Three linear equation groups for computing the coefficients of the Sommerfeld integrals are obtained according to the continuity condition of electric and magnetic fields across the interface between different layers, which are in correspondence with the TM wave produced by a vertical unit electric dipole and the TE or TM wave produced by a horizontal unit electric dipole, respectively. All the linear equation groups can be solved via the recursive algorithm. The dyadic Green＇s functions with source point and field point being in any layer can be conveniently obtained by merely changing the position of the elements within the source term of the linear equation groups. The problem of singularities occurring in the Sommerfeld integrals is efficiently solved by deforming the integration path in the complex plane. The expression of the dyadic Green＇s functions provided by this paper is terse in form and is easy to be programmed, and it does not overflow. Theoretical analysis and numerical examples show the accuracy and effectivity of the algorithm.展开更多
It is about fifty years since dyadic Green’s functions (DGF) were used to solveelectromagnetic boundary problems. However. by 1971 the DGF under normal boundaryconditions had been studied systematically with the meth...It is about fifty years since dyadic Green’s functions (DGF) were used to solveelectromagnetic boundary problems. However. by 1971 the DGF under normal boundaryconditions had been studied systematically with the method of Ohm-Rayleigh by C. T. Tai.展开更多
The problem about the complete form of the dyadic Green’s function is one of thefundamental problems in electromagnetic field and also a controversial one for a long time.Detailed derivations of several alternative r...The problem about the complete form of the dyadic Green’s function is one of thefundamental problems in electromagnetic field and also a controversial one for a long time.Detailed derivations of several alternative representations of the dyadic Green’s function inmany systems were given in Tai’s famous book.However,someone pointed out this formof the dyadic Green’s function was not complete,then an isolated singular term was展开更多
The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical...The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical results show the effects of tthe input impedance, which could be used in designing the Cavity-Backed Slot Antenna展开更多
The energy conservation in the radiation process by electron beam in a wave guidewith arbitrary cross section is proved.Some mistakes in Ref.[1]by myself are corrected.And theresults are extended to the waveguide syst...The energy conservation in the radiation process by electron beam in a wave guidewith arbitrary cross section is proved.Some mistakes in Ref.[1]by myself are corrected.And theresults are extended to the waveguide system with one shorted end.This result explains that theenergy conservation is intrinsic attributes of the Maxwell’s equation set.展开更多
The formula of input impedance of dipole antenna in Gigahertz Transverse ElectroM agnetic(GTEM) cell based on the dyadic Green's function is first obtained in this paper. The validation of the formula is verified ...The formula of input impedance of dipole antenna in Gigahertz Transverse ElectroM agnetic(GTEM) cell based on the dyadic Green's function is first obtained in this paper. The validation of the formula is verified by the results of theoretical derivation and simulation with well agreements. In comparison with the formula of input impedance in free space, the relationship between the change of input impedance with the length of antenna and the position of antenna in GTEM cell is obtained. In addition, some meaningful conclusions are presented, which not only can be referred by the further research of ElectroM agnetic Interference(EMI) measurements in GTEM cell, but also provide the theoretical basis for testing compensation and error analysis.展开更多
For real-time inversion and fast reconstruction of formation true resistivity, the forward modeling of electromagnetic wave logging while drilling is usually based on the transversely isotropic formation model with ve...For real-time inversion and fast reconstruction of formation true resistivity, the forward modeling of electromagnetic wave logging while drilling is usually based on the transversely isotropic formation model with vertical symmetry axis(VTI medium), but it only considers the horizontal and vertical resistivity. It has certain limitation during practical application. This paper presents a forward calculation method of electromagnetic wave logging while drilling in transversely isotropic(TTI) strata with inclined symmetry axis based on the Dyadic Green’s function. Anisotropic angle and azimuth are used to characterize TTI formation. The proposed algorithm is verified by numerical examples, the half-space electromagnetic wave reflection and transmission characteristics with different media are analyzed, and the necessity to use the new algorithm is pointed out. Numerical simulation also shows that there exist a critical borehole dip and critical anisotropic angle in TTI formation. Electromagnetic wave logging while drilling responses follows opposite rule before and after these two critical angles. Besides, the 'horns' at the interface are not only related to well deviation, resistivity contrast, but also related to anisotropic angle and anisotropic azimuth.展开更多
The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with all...The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with allowance for the mechanical exciton decay . The results of the numerical calculations of the partial and interference contributions of the bulk and radiative surface spectral modes to the EPL in the geometry of additional s- and p-polarized waves emitted into vacuum are analyzed. It is shown that the contributions of purely longitudinal excitons and their interference with polaritons of the upper dispersion branch near the longitudinal frequency ωL to the EPL are small (∼10% - 30%);nevertheless, they must be taken into account to obtain quantitative agreement with experimental data. Specifically these contributions are responsible for the formation of an additional line (along with the fundamental AT line) in the case of oblique incidence of radiation.展开更多
基金Sponsored by the Natural Science Foundation of Liaoning Province (Grant No.20092146)
文摘A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1B - （ωε）^-1γJ is given. The divergenceless and irrotational splitting of dyadic Dirac 8 function and Fourier transformation are used to directly obtain the divergenceless and irrotational component of spectral-domain dyadic Green＇s functions in chiral media. This method avoids using the dyadic Green＇s function eigenfunction expansion technique. The method given here can be generalized to a source-free region and an achiral case.
基金This project is supported by the National Science Fundation of China
文摘A new method for solving electromagnetic field boundary value problem is given.Byusing this method,the boundary value problem of the vector wave equation can be transformedinto the independent boundary value problem of scalar wave equations and the two additionalvector differential operations.All the dyadic Green’s functions got by eigenfunction expansionof the dyadic Green’s function can be got by this method easily and some of the dyadic Green’sfunctions for complex systems which are very difficult to get by the ordinary method have beengot by this new method.The dyadic Green’s function for a dielectric loaded cavity is one of thegiven examples.
文摘This paper presents a method to derive the Dyadic Green’s Function(DGF)ofa loaded rectangular waveguide by using the image method.In the calculation of the DGF,we use the integral transformation and replace the multi-infinite summation by a single one;thus it greatly simplifies the calculation and saves computer time.As an example of the DGF’sapplication,we give the moment method’s scattering field calculation of a metal sphere resting onthe broad wall of the loaded rectangular waveguide.Results of our calculations well agree withboth data of experiments performed in our laboratory and those are published.It is easy to seethat the method used in this paper can be expanded to other related waveguide problems.
基金Supported by the National Natural Science Foundation of China (No.50377001) and Tenth Five Year Key Items Foundation (No.2003SZ007) of Beijing Jiaotong Uni-versity.
文摘Herein a novel Dyadic Green’s Function (DGF) is presented to calculate the field in ElectroMag-netic Compatibility (EMC) chamber. Due to the difficulty of simulating the whole chamber environment, the analysis combines the DGF formulation and the FEM method, with the latter deals with the reflection from absorbers. With DGF formulation for infinite periodic array structures, this paper investigates electromagnetic field in chamber with truncated arrays. The reflection from the absorber serves as the virtual source contribut-ing to the total field. Hence the whole chamber field calculation can be separated from the work of absorber model set-up. Practically the field homogeneity test and Normal Site Attenuation (NSA) test are carried out to evaluate the chamber performance. Based on the method in this paper, the simulation results agree well with the test, and predict successfully the victim frequency points of the chamber.
基金the National Natural Science Foundation of China (Grant No. 60371020)National Defense Pre-research Foundation of China (Grant No. 9140a03020206dz0112)
文摘Based on the dipole source method, all components of the Green＇s functions in spectral domain are restructured concisely by four basis functions, and in terms of the two-level discrete complex image method （DCIM） with the high order Sommerfeld identities, an efficient algorithm for closed-form Green＇s functions in spatial domain in multilayered media is presented. This new work enjoys the advantages of the surface wave pole extraction directly carried out by the generalized integral path without troubles of that all components of Green＇s function in spectral domain should be reformed respectively in transmission line network analogy, and then the Green＇s functions for mixed-potential integral equation （MPIE） analysis in both near-field and far-field in multilayered media are obtained. In addition, the curl operator for coupled field in MPIE is avoided conveniently. It is especially applicable and useful to characterize the electromagnetic scattering by, and radiation in the presence of, the electrically large 3-D objects in multilayered media. The numerical results of the S-parameters of a microstrip periodic bandgap （PBG） filter, the radar cross section （RCS） of a large microstrip antenna array, the characteristics of scattering, and radiation from the three-dimensional （3-D） targets in multilayered media are obtained, to demonstrate better effectiveness and accuracy of this technique.
文摘A recursive algorithm is adopted for the computation of dyadic Green＇s functions in three-dimensional stratified uniaxial anisotropic media with arbitrary number of layers. Three linear equation groups for computing the coefficients of the Sommerfeld integrals are obtained according to the continuity condition of electric and magnetic fields across the interface between different layers, which are in correspondence with the TM wave produced by a vertical unit electric dipole and the TE or TM wave produced by a horizontal unit electric dipole, respectively. All the linear equation groups can be solved via the recursive algorithm. The dyadic Green＇s functions with source point and field point being in any layer can be conveniently obtained by merely changing the position of the elements within the source term of the linear equation groups. The problem of singularities occurring in the Sommerfeld integrals is efficiently solved by deforming the integration path in the complex plane. The expression of the dyadic Green＇s functions provided by this paper is terse in form and is easy to be programmed, and it does not overflow. Theoretical analysis and numerical examples show the accuracy and effectivity of the algorithm.
文摘It is about fifty years since dyadic Green’s functions (DGF) were used to solveelectromagnetic boundary problems. However. by 1971 the DGF under normal boundaryconditions had been studied systematically with the method of Ohm-Rayleigh by C. T. Tai.
文摘The problem about the complete form of the dyadic Green’s function is one of thefundamental problems in electromagnetic field and also a controversial one for a long time.Detailed derivations of several alternative representations of the dyadic Green’s function inmany systems were given in Tai’s famous book.However,someone pointed out this formof the dyadic Green’s function was not complete,then an isolated singular term was
文摘The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical results show the effects of tthe input impedance, which could be used in designing the Cavity-Backed Slot Antenna
文摘The energy conservation in the radiation process by electron beam in a wave guidewith arbitrary cross section is proved.Some mistakes in Ref.[1]by myself are corrected.And theresults are extended to the waveguide system with one shorted end.This result explains that theenergy conservation is intrinsic attributes of the Maxwell’s equation set.
基金Supported by Chinese Academy of Sciences(No.Y140110213)
文摘The formula of input impedance of dipole antenna in Gigahertz Transverse ElectroM agnetic(GTEM) cell based on the dyadic Green's function is first obtained in this paper. The validation of the formula is verified by the results of theoretical derivation and simulation with well agreements. In comparison with the formula of input impedance in free space, the relationship between the change of input impedance with the length of antenna and the position of antenna in GTEM cell is obtained. In addition, some meaningful conclusions are presented, which not only can be referred by the further research of ElectroM agnetic Interference(EMI) measurements in GTEM cell, but also provide the theoretical basis for testing compensation and error analysis.
基金Supported by the National Natural Science Foundation of China(41474100,41574118)
文摘For real-time inversion and fast reconstruction of formation true resistivity, the forward modeling of electromagnetic wave logging while drilling is usually based on the transversely isotropic formation model with vertical symmetry axis(VTI medium), but it only considers the horizontal and vertical resistivity. It has certain limitation during practical application. This paper presents a forward calculation method of electromagnetic wave logging while drilling in transversely isotropic(TTI) strata with inclined symmetry axis based on the Dyadic Green’s function. Anisotropic angle and azimuth are used to characterize TTI formation. The proposed algorithm is verified by numerical examples, the half-space electromagnetic wave reflection and transmission characteristics with different media are analyzed, and the necessity to use the new algorithm is pointed out. Numerical simulation also shows that there exist a critical borehole dip and critical anisotropic angle in TTI formation. Electromagnetic wave logging while drilling responses follows opposite rule before and after these two critical angles. Besides, the 'horns' at the interface are not only related to well deviation, resistivity contrast, but also related to anisotropic angle and anisotropic azimuth.
文摘The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with allowance for the mechanical exciton decay . The results of the numerical calculations of the partial and interference contributions of the bulk and radiative surface spectral modes to the EPL in the geometry of additional s- and p-polarized waves emitted into vacuum are analyzed. It is shown that the contributions of purely longitudinal excitons and their interference with polaritons of the upper dispersion branch near the longitudinal frequency ωL to the EPL are small (∼10% - 30%);nevertheless, they must be taken into account to obtain quantitative agreement with experimental data. Specifically these contributions are responsible for the formation of an additional line (along with the fundamental AT line) in the case of oblique incidence of radiation.
