IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)最新文献
The forces exerted on classical electric and magnetic dipoles by externally applied electromagnetic fields are derived from first principles. It is found, in accordance with Penfield and Haus (1967) and De Groot and Suttorp (1972), that the force on a magnetic dipole is the same for a perfectly conducting electric-current (Amperian) model and for a magnetic-charge model of the magnetic dipole, provided the sources of the externally applied field lie outside the dipole. However, if the dipoles lie within the polarization densities of the externally applied field, the force they experience depends on the model chosen for the dipoles (and for the polarization densities of the externally applied fields). The difference between the forces on point Amperian and magnetic-charge magnetic dipoles within the polarization densities of an external field has been used to demonstrate experimentally that neutrons scattered by the fields in ferromagnetic materials act like Amperian rather than magnetic-charge magnetic dipoles.
{"title":"Electromagnetic forces on point dipoles","authors":"A. Yaghjian","doi":"10.1109/APS.1999.789404","DOIUrl":"https://doi.org/10.1109/APS.1999.789404","url":null,"abstract":"The forces exerted on classical electric and magnetic dipoles by externally applied electromagnetic fields are derived from first principles. It is found, in accordance with Penfield and Haus (1967) and De Groot and Suttorp (1972), that the force on a magnetic dipole is the same for a perfectly conducting electric-current (Amperian) model and for a magnetic-charge model of the magnetic dipole, provided the sources of the externally applied field lie outside the dipole. However, if the dipoles lie within the polarization densities of the externally applied field, the force they experience depends on the model chosen for the dipoles (and for the polarization densities of the externally applied fields). The difference between the forces on point Amperian and magnetic-charge magnetic dipoles within the polarization densities of an external field has been used to demonstrate experimentally that neutrons scattered by the fields in ferromagnetic materials act like Amperian rather than magnetic-charge magnetic dipoles.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129826858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wavelet theory is becoming a very useful tool to characterize electromagnetic structures due to the excellent properties of wavelet families for the accurate representation of functions and operators. Up to now, wavelet theory has been applied successfully to electromagnetic integral equations solved through moment methods. However, in this paper, the computation of the modal behavior of rectangular waveguides strongly perturbed by axial cylindrical conducting objects is taken via the Nystrom method, which is an elegant and simple procedure for solving integral equations. In order to improve the efficiency, wavelet-like bases are used to expand the unknown electric current. Therefore, memory requirements and computational costs are reduced dramatically.
{"title":"Efficient waveguide mode computation using wavelet-like basis functions","authors":"S. Cogollos, A. Vidal, H. Esteban, V. Boria","doi":"10.1109/APS.1999.789153","DOIUrl":"https://doi.org/10.1109/APS.1999.789153","url":null,"abstract":"Wavelet theory is becoming a very useful tool to characterize electromagnetic structures due to the excellent properties of wavelet families for the accurate representation of functions and operators. Up to now, wavelet theory has been applied successfully to electromagnetic integral equations solved through moment methods. However, in this paper, the computation of the modal behavior of rectangular waveguides strongly perturbed by axial cylindrical conducting objects is taken via the Nystrom method, which is an elegant and simple procedure for solving integral equations. In order to improve the efficiency, wavelet-like bases are used to expand the unknown electric current. Therefore, memory requirements and computational costs are reduced dramatically.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128217859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A discrete vector calculus on a lattice is developed based on primary and dual lattices that support scalar as well as vector fields with collocated components. The resulting discrete vector calculus is applied to electromagnetic theory and is, by construction, consistent with both the integral and differential forms of Maxwell's equations. In its own right, the resulting discrete space-time (DST) method does not hold any particular advantage over the standard Yee algorithm other than improved stability. The the time-domain element (TDE) method is presented, which may be viewed as a reinterpretation and generalization of the Yee algorithm. The formulations of the TDE and DST methods are such that it combination of the two is quite transparent. The combined algorithm has the advantage in that it retains the local nature of each as well as taking advantage of the obvious complementarity of the two. The result is a robust, highly accurate, and efficient algorithm that inherently satisfies boundary conditions on dielectric interfaces.
{"title":"A new FDTD formulation with reduced dispersion for the simulation of wave propagation through inhomogeneous media","authors":"E. Forgy, W. Chew","doi":"10.1109/APS.1999.789556","DOIUrl":"https://doi.org/10.1109/APS.1999.789556","url":null,"abstract":"A discrete vector calculus on a lattice is developed based on primary and dual lattices that support scalar as well as vector fields with collocated components. The resulting discrete vector calculus is applied to electromagnetic theory and is, by construction, consistent with both the integral and differential forms of Maxwell's equations. In its own right, the resulting discrete space-time (DST) method does not hold any particular advantage over the standard Yee algorithm other than improved stability. The the time-domain element (TDE) method is presented, which may be viewed as a reinterpretation and generalization of the Yee algorithm. The formulations of the TDE and DST methods are such that it combination of the two is quite transparent. The combined algorithm has the advantage in that it retains the local nature of each as well as taking advantage of the obvious complementarity of the two. The result is a robust, highly accurate, and efficient algorithm that inherently satisfies boundary conditions on dielectric interfaces.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128424728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Wlodarczyk, J. Nadobny, P. Wust, G. Monich, P. Deuflhard, R. Felix
The purpose of this contribution is to develop high performance short antenna structures which can be used as basic array elements of the 3D phased array for hyperthermia (HT) applications in the pelvis. The numerical design of basic array elements of the 3D HT applicator has been performed in a systematic way applying the finite-difference time-domain (FDTD) method. Some modifications of the FDTD method specific for antenna design have been implemented. Thus, approximations for modelling of thin wires and thin layers have been made as well as source environments suitable for comparisons with network analyzer measurements have been modeled. An additional verification has been performed applying another numerical tool, the volume surface integral equation (VSIE).
{"title":"Systematic design of antennas for cylindrical 3D phased array hyperthermia applicator","authors":"W. Wlodarczyk, J. Nadobny, P. Wust, G. Monich, P. Deuflhard, R. Felix","doi":"10.1109/APS.1999.789482","DOIUrl":"https://doi.org/10.1109/APS.1999.789482","url":null,"abstract":"The purpose of this contribution is to develop high performance short antenna structures which can be used as basic array elements of the 3D phased array for hyperthermia (HT) applications in the pelvis. The numerical design of basic array elements of the 3D HT applicator has been performed in a systematic way applying the finite-difference time-domain (FDTD) method. Some modifications of the FDTD method specific for antenna design have been implemented. Thus, approximations for modelling of thin wires and thin layers have been made as well as source environments suitable for comparisons with network analyzer measurements have been modeled. An additional verification has been performed applying another numerical tool, the volume surface integral equation (VSIE).","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130319621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical electromagnetic modeling involves three distinct phases: the preparation of the geometric input data; running the numerical model; and evaluation or viewing/visualization of the model output. This paper presents visualization examples for frequency domain codes. Visualization quantities for antenna and scattering examples include geometry, currents, near fields, radiation images, and far field patterns that can be animated in time and space. A PC computer based EM visualization tool for post processing the results of any frequency domain (FD) model has been developed. The input data required from a FD code is simply the triangle geometry (points and triangle connectivity) and the current at each point (vertex) for each antenna or scattering excitation of the body. Current displays, near fields, radiation images, and far fields are then computed from the input current and geometry. The results presented were obtained from a triangular patch and body of revolution MOM codes.
{"title":"Electromagnetic visualization for antennas and scattering","authors":"J. Shaeffer, B. Cooper","doi":"10.1109/APS.1999.789086","DOIUrl":"https://doi.org/10.1109/APS.1999.789086","url":null,"abstract":"Numerical electromagnetic modeling involves three distinct phases: the preparation of the geometric input data; running the numerical model; and evaluation or viewing/visualization of the model output. This paper presents visualization examples for frequency domain codes. Visualization quantities for antenna and scattering examples include geometry, currents, near fields, radiation images, and far field patterns that can be animated in time and space. A PC computer based EM visualization tool for post processing the results of any frequency domain (FD) model has been developed. The input data required from a FD code is simply the triangle geometry (points and triangle connectivity) and the current at each point (vertex) for each antenna or scattering excitation of the body. Current displays, near fields, radiation images, and far fields are then computed from the input current and geometry. The results presented were obtained from a triangular patch and body of revolution MOM codes.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130533472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The finite difference in time domain method was used to study the wave propagation in a microstrip line. The boundary condition implemented at the excitation source plane causes an amplification effect on the resulting field at the source plane. The amplification factor depends on the time, spatial intervals and the effective dielectric constant of the microstrip line. The numerical origin of this effect is investigated.
{"title":"Numerical amplification of the excitation source in waveguide structure","authors":"L. Liou, L. Ho","doi":"10.1109/APS.1999.788322","DOIUrl":"https://doi.org/10.1109/APS.1999.788322","url":null,"abstract":"The finite difference in time domain method was used to study the wave propagation in a microstrip line. The boundary condition implemented at the excitation source plane causes an amplification effect on the resulting field at the source plane. The amplification factor depends on the time, spatial intervals and the effective dielectric constant of the microstrip line. The numerical origin of this effect is investigated.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129070318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In previous publications, the authors have proposed a methodology for the practical implementation of the Nedelec's (1980) first family of curl-conforming tetrahedral elements. The implementations corresponding to orders higher than one exhibit important differences with respect to those appeared in the literature. This paper deals with the assembly of the higher-order finite elements thus obtained. In particular, two different options are proposed to define the degrees of freedom associated to the faces of neighboring elements. Both options allow one to perform the computations over the parent element, while providing the tangential continuity through elements when utilizing the conventional finite element assembly procedure. The advantages and disadvantages of the two options are compared.
{"title":"On the assembly of 3D higher-order Nedelec curl-conforming tetrahedral elements","authors":"L. García-Castillo, M. Salazar-Palma","doi":"10.1109/APS.1999.789348","DOIUrl":"https://doi.org/10.1109/APS.1999.789348","url":null,"abstract":"In previous publications, the authors have proposed a methodology for the practical implementation of the Nedelec's (1980) first family of curl-conforming tetrahedral elements. The implementations corresponding to orders higher than one exhibit important differences with respect to those appeared in the literature. This paper deals with the assembly of the higher-order finite elements thus obtained. In particular, two different options are proposed to define the degrees of freedom associated to the faces of neighboring elements. Both options allow one to perform the computations over the parent element, while providing the tangential continuity through elements when utilizing the conventional finite element assembly procedure. The advantages and disadvantages of the two options are compared.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129125124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A prototype test cell for generating standard fields suitable for antenna calibration from DC to 40 GHz has been developed and tested. A 1 meter scale model of the Co-Conical Field Generation System (CFGS), an expanding, constant impedance coaxial transmission system has been constructed. By maintaining symmetry throughout the cell, a uniform and calculable wavefront is established. This symmetry also maintains the dominant TEM mode structure and more importantly, allows for the gradual and efficient termination of the incident energy. Simple termination schemes have generally provided better than 20 dB absorption of the injected energy with complex designs showing much more promise. The field structure within the test volume has been mapped by measuring the reflections by a small passive scatterer. The measurement results agree well with transmission line theory and show no significant signs of mode degradation as energy propagates down the cell. Various numerical techniques agree well with the measurement results and transmission line equations, allowing for further study of scattering effects within the cell.
{"title":"The Co-Conical Field Generation System-a 40 GHz antenna calibration cell","authors":"D. Novotny, A. Ondrejka, R. Johnk","doi":"10.1109/APS.1999.789428","DOIUrl":"https://doi.org/10.1109/APS.1999.789428","url":null,"abstract":"A prototype test cell for generating standard fields suitable for antenna calibration from DC to 40 GHz has been developed and tested. A 1 meter scale model of the Co-Conical Field Generation System (CFGS), an expanding, constant impedance coaxial transmission system has been constructed. By maintaining symmetry throughout the cell, a uniform and calculable wavefront is established. This symmetry also maintains the dominant TEM mode structure and more importantly, allows for the gradual and efficient termination of the incident energy. Simple termination schemes have generally provided better than 20 dB absorption of the injected energy with complex designs showing much more promise. The field structure within the test volume has been mapped by measuring the reflections by a small passive scatterer. The measurement results agree well with transmission line theory and show no significant signs of mode degradation as energy propagates down the cell. Various numerical techniques agree well with the measurement results and transmission line equations, allowing for further study of scattering effects within the cell.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129210351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have presented an accurate and efficient method for S-parameter calculation. The method uses a variation on the total field-scattered field formalism, the modes are injected and extracted at the interface between the total field and the error field regions. As such the propagated energy never actually reaches the boundary conditions, so these conditions can be less stringent, and should require less resources. Furthermore, the mode distributions are used to excite the structure and to calculate the amplitude of the propagating mode. This allows us to place both the excitation mechanism and the port regions very close to the simulated structure, again saving resources, as well as preserving the accuracy of the method. However, due to the dispersion of non-TEM modes, this method can only be used if the mode of interest is TEM. Our method has been compared with the method of moments approach and the results are almost identical.
{"title":"Efficient FDTD S-parameter calculation of microwave structures with TEM ports","authors":"S. Van den Berghe, F. Olyslager, D. De Zutter","doi":"10.1109/APS.1999.789500","DOIUrl":"https://doi.org/10.1109/APS.1999.789500","url":null,"abstract":"We have presented an accurate and efficient method for S-parameter calculation. The method uses a variation on the total field-scattered field formalism, the modes are injected and extracted at the interface between the total field and the error field regions. As such the propagated energy never actually reaches the boundary conditions, so these conditions can be less stringent, and should require less resources. Furthermore, the mode distributions are used to excite the structure and to calculate the amplitude of the propagating mode. This allows us to place both the excitation mechanism and the port regions very close to the simulated structure, again saving resources, as well as preserving the accuracy of the method. However, due to the dispersion of non-TEM modes, this method can only be used if the mode of interest is TEM. Our method has been compared with the method of moments approach and the results are almost identical.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130574602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Taguchi, H. Somiya, T. Fujimoto, M. Hirose, K. Komiyama
The phased array active antenna composed of two active loop antennas has been proposed for the reception antennas of the future digital television in Japan and its actual gain and front-to-back ratio have been analyzed.
{"title":"Phase array active loop antenna for digital television receiver","authors":"M. Taguchi, H. Somiya, T. Fujimoto, M. Hirose, K. Komiyama","doi":"10.1109/APS.1999.789274","DOIUrl":"https://doi.org/10.1109/APS.1999.789274","url":null,"abstract":"The phased array active antenna composed of two active loop antennas has been proposed for the reception antennas of the future digital television in Japan and its actual gain and front-to-back ratio have been analyzed.","PeriodicalId":391546,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130635004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010)
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