: Basic technological work done on a 20/30 GHz L-SAT propagation experiment receiver is presented... more : Basic technological work done on a 20/30 GHz L-SAT propagation experiment receiver is presented, covering receiver configuration, measurement systems, Gunn-diode oscillators, fin-line transitions and cylindrical near field antenna measurement systems. (Author)
A novel integral formulation of the Mea- sured Equation of Invariance method is derived from the ... more A novel integral formulation of the Mea- sured Equation of Invariance method is derived from the reciprocity theorem. This formulation uses the electric and magnetic Green's functions of the envi- ronment to obtain a matrix equation for the induced surface current with the same number of unknowns as the conventional Boundary Element - Method of Moments (BE-MOM) approach. However, the matrix that must be inverted in the new formulation is sparse and circulant, with only three non-zero elements per row. Sample results for two-dimensional TM and TE problems with perfectly conducting scatterers show enormous CPU time and memory savings over the conventional BEM-MOM approach. The new formula- tion has important advantages over the original finite difference formulation of MEI, but also shares some of its limitations.
In the study of electromagnetic radiation effects over dielectric bodies, effective numerical met... more In the study of electromagnetic radiation effects over dielectric bodies, effective numerical methods are needed. At present, there is a lack of tools for measuring this effects and due to the huge growth of microwave devices, like cellular radio telephones working close to the human body, it is necessary to develop accurate numerical methods for evaluating those effects. One of
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010), 1999
IEEE Antennas and Propagation Society International Symposium 1992 Digest, 1992
An iterative spectral propagation algorithm is developed which introduces new features that impro... more An iterative spectral propagation algorithm is developed which introduces new features that improve the numerical efficiency and accuracy of the spectral iteration technique and the spectral incremental propagation procedure. The new spectral algorithm is particularly useful for analyzing closed problems where the boundary structure is too large for low-frequency matrix methods and too complex for high-frequency approximations. The scope of application includes the radar cross section of cavities, waveguide discontinuities and filters, and conformed or corrugated horn antenna analysis. The method is also valid for scattering problems in free space, but the continuous spectrum of nonperiodic fields together with the periodicity of the discrete Fourier transform require a very high number of field samples. For that reason, the efficiency of the algorithm may be worse than that of matrix methods for very complex scatterers and worse than that of high-frequency methods for large and simple objects. The main drawback is that boundary conditions are restricted to perfect electric or magnetic conductors, so that electric loading cannot be considered
: Basic technological work done on a 20/30 GHz L-SAT propagation experiment receiver is presented... more : Basic technological work done on a 20/30 GHz L-SAT propagation experiment receiver is presented, covering receiver configuration, measurement systems, Gunn-diode oscillators, fin-line transitions and cylindrical near field antenna measurement systems. (Author)
A novel integral formulation of the Mea- sured Equation of Invariance method is derived from the ... more A novel integral formulation of the Mea- sured Equation of Invariance method is derived from the reciprocity theorem. This formulation uses the electric and magnetic Green's functions of the envi- ronment to obtain a matrix equation for the induced surface current with the same number of unknowns as the conventional Boundary Element - Method of Moments (BE-MOM) approach. However, the matrix that must be inverted in the new formulation is sparse and circulant, with only three non-zero elements per row. Sample results for two-dimensional TM and TE problems with perfectly conducting scatterers show enormous CPU time and memory savings over the conventional BEM-MOM approach. The new formula- tion has important advantages over the original finite difference formulation of MEI, but also shares some of its limitations.
In the study of electromagnetic radiation effects over dielectric bodies, effective numerical met... more In the study of electromagnetic radiation effects over dielectric bodies, effective numerical methods are needed. At present, there is a lack of tools for measuring this effects and due to the huge growth of microwave devices, like cellular radio telephones working close to the human body, it is necessary to develop accurate numerical methods for evaluating those effects. One of
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.99CH37010), 1999
IEEE Antennas and Propagation Society International Symposium 1992 Digest, 1992
An iterative spectral propagation algorithm is developed which introduces new features that impro... more An iterative spectral propagation algorithm is developed which introduces new features that improve the numerical efficiency and accuracy of the spectral iteration technique and the spectral incremental propagation procedure. The new spectral algorithm is particularly useful for analyzing closed problems where the boundary structure is too large for low-frequency matrix methods and too complex for high-frequency approximations. The scope of application includes the radar cross section of cavities, waveguide discontinuities and filters, and conformed or corrugated horn antenna analysis. The method is also valid for scattering problems in free space, but the continuous spectrum of nonperiodic fields together with the periodicity of the discrete Fourier transform require a very high number of field samples. For that reason, the efficiency of the algorithm may be worse than that of matrix methods for very complex scatterers and worse than that of high-frequency methods for large and simple objects. The main drawback is that boundary conditions are restricted to perfect electric or magnetic conductors, so that electric loading cannot be considered
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Papers by A. Cardama