Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/659
Sun, 23 Apr 2017 23:52:16 GMT2017-04-23T23:52:16ZDesign of single shaped reflector antennas with a single feed applying genetic algorithms and graphical processing techniques
http://hdl.handle.net/2117/103593
Design of single shaped reflector antennas with a single feed applying genetic algorithms and graphical processing techniques
Vall-Llossera Ferran, Mercedes Magdalena; Rius Casals, Juan Manuel; García, M; Duffo Ubeda, Núria
A genetic algorithm GA has been de ( ) eloped for designing
single-shaped reflector antennas for the synthesis of shaped contour
beams. The graphical processing technique is used in order to obtain the
antenna radiation patterns ery efficiently. Results comparing with the
classical conjugate gradient are included to pro ide alidation. 2000
John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 358 361,
2000.
Thu, 20 Apr 2017 15:21:40 GMThttp://hdl.handle.net/2117/1035932017-04-20T15:21:40ZVall-Llossera Ferran, Mercedes MagdalenaRius Casals, Juan ManuelGarcía, MDuffo Ubeda, NúriaA genetic algorithm GA has been de ( ) eloped for designing
single-shaped reflector antennas for the synthesis of shaped contour
beams. The graphical processing technique is used in order to obtain the
antenna radiation patterns ery efficiently. Results comparing with the
classical conjugate gradient are included to pro ide alidation. 2000
John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 358 361,
2000.Variations on the fractal Sierpinski antenna flare angle
http://hdl.handle.net/2117/103586
Variations on the fractal Sierpinski antenna flare angle
Puente Baliarda, Carles; Navarro Bernal, Manuel; Romeu Robert, Jordi; Pous Andrés, Rafael
A further investigation on the fractal multiband Sierpinski antenna is introduced. It is shown that a variation on the antenna's flare angle is translated into a shift of the operating bands, as well as into a change in the impedance level and radiation patterns. The contribution of those variations to the truncation effect is outlined.
Thu, 20 Apr 2017 14:30:33 GMThttp://hdl.handle.net/2117/1035862017-04-20T14:30:33ZPuente Baliarda, CarlesNavarro Bernal, ManuelRomeu Robert, JordiPous Andrés, RafaelA further investigation on the fractal multiband Sierpinski antenna is introduced. It is shown that a variation on the antenna's flare angle is translated into a shift of the operating bands, as well as into a change in the impedance level and radiation patterns. The contribution of those variations to the truncation effect is outlined.On the accuracy of the Adaptive Cross Approximation algorithm
http://hdl.handle.net/2117/102208
On the accuracy of the Adaptive Cross Approximation algorithm
Heldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan Manuel
This contribution identifies an often ignored source of uncertainty in the accuracy of the Adaptive Cross Approximation (ACA) algorithm.
Thu, 09 Mar 2017 13:43:25 GMThttp://hdl.handle.net/2117/1022082017-03-09T13:43:25ZHeldring, AlexanderÚbeda Farré, EduardRius Casals, Juan ManuelThis contribution identifies an often ignored source of uncertainty in the accuracy of the Adaptive Cross Approximation (ACA) algorithm.Self-similar current distribution on fractal Sierpinski antenna verified with infrared thermograms
http://hdl.handle.net/2117/101406
Self-similar current distribution on fractal Sierpinski antenna verified with infrared thermograms
González Arbesú, José María; Puente Baliarda, Carles; Romeu Robert, Jordi; Aguasca Solé, Alberto
Experimental verification of the fractal Sierpinski antenna surface current distribution is presented. Measured data from an infrared camera agree with numerical data showing a self-similar behavior in the current density distribution over the fractal antenna surface. This result gives a better insight on the multiband behavior of the fractal-shape antenna.
Wed, 22 Feb 2017 18:26:45 GMThttp://hdl.handle.net/2117/1014062017-02-22T18:26:45ZGonzález Arbesú, José MaríaPuente Baliarda, CarlesRomeu Robert, JordiAguasca Solé, AlbertoExperimental verification of the fractal Sierpinski antenna surface current distribution is presented. Measured data from an infrared camera agree with numerical data showing a self-similar behavior in the current density distribution over the fractal antenna surface. This result gives a better insight on the multiband behavior of the fractal-shape antenna.Application of the conjugate gradient method to a self-matching network for industrial microwave heating antennas
http://hdl.handle.net/2117/101401
Application of the conjugate gradient method to a self-matching network for industrial microwave heating antennas
Mallorquí Franquet, Jordi Joan; Aguasca Solé, Alberto; Cardama Aznar, Ángel; Pages, R; Haro, J M
One of the main problems regarding the efficiency in a heating industrial system using high power microwaves is related with the uncontrolled changes on the load. These changes can be caused both by the different kinds of materials to be processed in the same oven and by the temperature rise which modifies the material's physical properties, particularly its dielectric permittivity. Usually, the microwave generator is matched to the antenna feeding the oven by means of a waveguide matching system, typically a two, three or four capacitive-screw tuner empirically adjusted for a given load. Once the heating process is started, the temperature dependence of the complex permittivity usually changes the impedance seen by the generator, worsening the mismatch factor and reducing the efficiency of the heating process. A similar process happens when the load is inhomogeneous or discontinuous; it is not feasible to manually re-adjust the matching network for every different sample processed. Until now the solution has been simple but highly inefficient: to increase the incident power in order to overcome the mismatching effects.
Wed, 22 Feb 2017 18:11:12 GMThttp://hdl.handle.net/2117/1014012017-02-22T18:11:12ZMallorquí Franquet, Jordi JoanAguasca Solé, AlbertoCardama Aznar, ÁngelPages, RHaro, J MOne of the main problems regarding the efficiency in a heating industrial system using high power microwaves is related with the uncontrolled changes on the load. These changes can be caused both by the different kinds of materials to be processed in the same oven and by the temperature rise which modifies the material's physical properties, particularly its dielectric permittivity. Usually, the microwave generator is matched to the antenna feeding the oven by means of a waveguide matching system, typically a two, three or four capacitive-screw tuner empirically adjusted for a given load. Once the heating process is started, the temperature dependence of the complex permittivity usually changes the impedance seen by the generator, worsening the mismatch factor and reducing the efficiency of the heating process. A similar process happens when the load is inhomogeneous or discontinuous; it is not feasible to manually re-adjust the matching network for every different sample processed. Until now the solution has been simple but highly inefficient: to increase the incident power in order to overcome the mismatching effects.near field to far field tranfsormation of bipolar measurements by equivalent magnetic current approach
http://hdl.handle.net/2117/101399
near field to far field tranfsormation of bipolar measurements by equivalent magnetic current approach
Blanch Boris, Sebastián; Romeu Robert, Jordi
An equivalent magnetic current (EMC) approach has been proposed as an alternative method to the classical modal formulation for computing the far-field pattern of a radiating antenna from planar near-field measurements. The attractiveness of this EMC approach includes the possibility of producing the correct far-field pattern in all regions in front of a planar antenna under test (AUT), a drawback of the classical modal formulation due to its dependence on the Fourier transform and assumptions which must be made about the field outside of the measurement zone, and its adaptability to both irregularly sampled and non-canonical near-field measurement surfaces. A drawback of the EMC approach, however, is its significantly larger computational requirements. A comparison of the EMC and classical modal approaches for near-field to far-field transformation is examined in terms of the resultant far-field patterns. Measurement results for a waveguide-fed slot array using the UCLA bi-polar planar near-field measurement scanner are presented. An implementation of the EMC approach for the bi-polar geometry is described and results obtained using different subsets of the measured bi-polar near-field data are presented and compared to that obtained using the classical modal approach.
Wed, 22 Feb 2017 18:01:37 GMThttp://hdl.handle.net/2117/1013992017-02-22T18:01:37ZBlanch Boris, SebastiánRomeu Robert, JordiAn equivalent magnetic current (EMC) approach has been proposed as an alternative method to the classical modal formulation for computing the far-field pattern of a radiating antenna from planar near-field measurements. The attractiveness of this EMC approach includes the possibility of producing the correct far-field pattern in all regions in front of a planar antenna under test (AUT), a drawback of the classical modal formulation due to its dependence on the Fourier transform and assumptions which must be made about the field outside of the measurement zone, and its adaptability to both irregularly sampled and non-canonical near-field measurement surfaces. A drawback of the EMC approach, however, is its significantly larger computational requirements. A comparison of the EMC and classical modal approaches for near-field to far-field transformation is examined in terms of the resultant far-field patterns. Measurement results for a waveguide-fed slot array using the UCLA bi-polar planar near-field measurement scanner are presented. An implementation of the EMC approach for the bi-polar geometry is described and results obtained using different subsets of the measured bi-polar near-field data are presented and compared to that obtained using the classical modal approach.Application of the boundary elements method to 3-d radiation problem
http://hdl.handle.net/2117/100985
Application of the boundary elements method to 3-d radiation problem
Abad, J.; Duffo Ubeda, Núria; Rius Casals, Juan Manuel; Cruellas Ibarz, Juan Carlos
In order to analyze the electromagnetic fields generated by perfectly conducting bodies composed by interconnected wires and solid objects, whichever its geometry, the Boundary Element Method is applied. The basic formulation and the associated items are commented. Results of problems of radiation are given and compared with available analytic solutions.
Tue, 14 Feb 2017 13:40:02 GMThttp://hdl.handle.net/2117/1009852017-02-14T13:40:02ZAbad, J.Duffo Ubeda, NúriaRius Casals, Juan ManuelCruellas Ibarz, Juan CarlosIn order to analyze the electromagnetic fields generated by perfectly conducting bodies composed by interconnected wires and solid objects, whichever its geometry, the Boundary Element Method is applied. The basic formulation and the associated items are commented. Results of problems of radiation are given and compared with available analytic solutions.Bidimensional scattering of tm and te polarized waves by dielectric
http://hdl.handle.net/2117/100982
Bidimensional scattering of tm and te polarized waves by dielectric
Mallorquí Franquet, Jordi Joan; Vaquer Bonnin, Miguel; Cardama Aznar, Ángel; Jofre Roca, Lluís
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 the most efficient and extensively used method is the FFT-CGM (Fast-Fourier-Transform Conjugate Gradient Method). In this paper, algorithms for solving the two-dimensional scattering of transversal magnetic (TM) and transversal electric (TE) polarized waves by a lossy dielectric and metallic objects are presented. At the same time, the SAR (Specific Absorption Rate) of tissues and the modified radiation diagrams when the body is present are obtained from the diffracted fields.
Tue, 14 Feb 2017 13:22:39 GMThttp://hdl.handle.net/2117/1009822017-02-14T13:22:39ZMallorquí Franquet, Jordi JoanVaquer Bonnin, MiguelCardama Aznar, ÁngelJofre Roca, LluísIn 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 the most efficient and extensively used method is the FFT-CGM (Fast-Fourier-Transform Conjugate Gradient Method). In this paper, algorithms for solving the two-dimensional scattering of transversal magnetic (TM) and transversal electric (TE) polarized waves by a lossy dielectric and metallic objects are presented. At the same time, the SAR (Specific Absorption Rate) of tissues and the modified radiation diagrams when the body is present are obtained from the diffracted fields.RCS of engine inlets by a spectral iterative technique
http://hdl.handle.net/2117/100933
RCS of engine inlets by a spectral iterative technique
Rius Casals, Juan Manuel; Lozano, Angel; Cardama Aznar, Ángel
A novel algorithm designed to compute efficiently and accurately the HF electromagnetic scattering from open-ended waveguide cavities is presented. The cavity is converted into a stepped-waveguide model so that the field spectrums are propagated, forward and backward, along each waveguide section. As boundary conditions for perfect electric conductors are applied via image theory, they are of local nature and take into account only the first order interactions between each pair of waveguide sections. Accordingly, additional forward-backward iterations must be performed if multiple interactions are to be taken into account. Finally, the RCS due to the interior irradiation is calculated by a Kirchhoff-based aperture integral. Good agreement with Method of Moments and Hybrid Modal solutions is found, as well as with experimental data, for 2-D and 3-D cavities.
Mon, 13 Feb 2017 15:19:14 GMThttp://hdl.handle.net/2117/1009332017-02-13T15:19:14ZRius Casals, Juan ManuelLozano, AngelCardama Aznar, ÁngelA novel algorithm designed to compute efficiently and accurately the HF electromagnetic scattering from open-ended waveguide cavities is presented. The cavity is converted into a stepped-waveguide model so that the field spectrums are propagated, forward and backward, along each waveguide section. As boundary conditions for perfect electric conductors are applied via image theory, they are of local nature and take into account only the first order interactions between each pair of waveguide sections. Accordingly, additional forward-backward iterations must be performed if multiple interactions are to be taken into account. Finally, the RCS due to the interior irradiation is calculated by a Kirchhoff-based aperture integral. Good agreement with Method of Moments and Hybrid Modal solutions is found, as well as with experimental data, for 2-D and 3-D cavities.Perspectives of the european academic research in the microwave..
http://hdl.handle.net/2117/100932
Perspectives of the european academic research in the microwave..
Cardama Aznar, Ángel
Mon, 13 Feb 2017 15:12:18 GMThttp://hdl.handle.net/2117/1009322017-02-13T15:12:18ZCardama Aznar, Ángel