Examinando por Autor "Jurado Lucena, A."

Mostrando 1 - 7 de 7

Restringido
Application of Artificial Neural Networks to Complex Dielectric Constant Estimation from Free-Space Measurements
(Springer Link, 2009-03-16) Jurado Lucena, A.; Escot Bocanegra, D.; Poyatos Martínez, D.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
Adequate characterization of materials allows the engineer to select the best option for each application. Apart from mechanical or environmental characterization, last decades’ rise in the exploitation of the electromagnetic spectrum has made increasingly important to understand and explain the behavior of materials also in that ambit. The electromagnetic properties of non-magnetic materials are governed by their intrinsic permittivity or dielectric constant and free-space measurements is one of the various methods employed to estimate this quantity at microwave frequencies. This paper proposes the application of Artificial Neural Networks (ANNs) to extract the dielectric constant of materials from the reflection coefficient obtained by free-space measurements. In this context, two kind of ANNs are examined: Multilayer Perceptron (MLP) and Radial Basis Function (RBF) networks. Simulated materials are utilized to train the networks with and without noise and performance is tested using an actual material sample measured by the authors in an anechoic chamber.
Restringido
Application of FDTD to HRRP Generation of a Cavity Model for NCTI Purposes
(Institute of Electrical and Electronics Engineers, 2011-07-04) Fernandez Recio, R.; Escot Bocanegra, D.; Poyatos Martínez, D.; Jurado Lucena, A.; Errasti Alcalá, B.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
The application of a time-domain electromagnetic simulation code to a realistic and challenging problem like the high-resolution range profile (HRRP) generation of an inlet cavity model is presented in this paper. HRRPs can be used to accomplish noncooperative target identification (NCTI) of aircrafts by means of radar, and the database needed in this technique tends to be populated with predicted data obtained with software tools. Most codes employed with these purposes are frequency domain methods, which need multiple simulations at different adequately chosen frequencies, as well as some postprocessing, to get a radar signature. Instead, this paper focuses on finite difference time domain (FDTD) analysis of the response of a cavity, because of the relevance of these parts of an aircraft in the overall signature, and numerical results are compared with measurements performed by the authors in an anechoic chamber. This work also shows the advantages of using an electromagnetic code based on time domain for HRRP generation.
Restringido
Joint Direction of Arrival and amplitude estimation using Particle Swarm Optimization and a single snapshot
(Institute of Electrical and Electronics Engineers, 2010-05-09) Errasti Alcalá, B.; Escot Bocanegra, D.; Poyatos Martínez, D.; Jurado Lucena, A.; Fernández Recio, R.; Instituto Nacional de Técnica Aeroespacial (INTA)
Direction of Arrival (DOA) estimation is a problem which concerns very diverse fields of interest. In most applications, not only the DOA but also the estimation of the amplitude of the incoming signals is becoming an important issue. In that sense, Particle Swarm Optimization (PSO) has shown a great capability to solve the DOA problem accurately and this communication presents a method to estimate both the amplitude and the Direction of Arrival of several incoming signals of a given wavelength.
Restringido
Methodology to Achieve Accurate Non Cooperative Target Identification Using High Resolution Radar and a Synthetic Database
(Springer Link, 2010-07-02) Jurado Lucena, A.; Errasti Alcalá, B.; Escot Bocanegra, D.; Fernández Recio, R.; Poyatos Martínez, D.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
In the last few years, there is a great interest in developing an identification system capable to make a reliable classification of aircrafts into different groups (friendly, hostile or neutral). Depending on the context in which these systems are deployed, incorrect identification may lead to serious problems, such as fratricide or engagement of civilian aircrafts. Different techniques have been researched to face this problem, but non-cooperative ones have awakened more interest because they do not require aircraft collaboration. Non Cooperative Target Identification (NCTI) using radar is a complex task, mainly due to the fact that a database of possible targets is needed. To populate this database, Radar Cross Section (RCS) predictions produced by computer simulation seem to be the most feasible way to perform this task, since measurements alone cannot cover the vast range of targets, configurations and required aspect angles. These predictions are typically performed in the frequency domain and a specific processing must be done to obtain both High Resolution Range Profiles (HRRPs) and 2D Inverse Synthetic Aperture Radar (2D-ISAR) images. This paper shows a methodology to face the NCTI task, which use both synthetic HRRPs and 2D-ISAR to achieve an accurate identification.
Acceso Abierto
New Benchmark Radar Targets for Scattering Analysis and Electromagnetic Software Validation
(The EM Academy, 2008-05-14) Escot Bocanegra, D.; Poyatos Martínez, D.; Fernández Recio, R.; Jurado Lucena, A.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
A validation process, in which simulations and measurements are compared, is necessary to have confidence in the results obtained by numerical methods that solve scattering problems. This paper presents Radar Cross Section (RCS) measurements of new targets suitable for electromagnetic software comparison and validation. These measurements can be used as an RCS reference data for testing existing and future codes, as well as for the analysis of the scattering mechanisms.
Restringido
RCS measurements and predictions of different targets for radar benchmark purpose
(Institute of Electrical and Electronics Engineers, 2009-09-18) Férnandez Recio, R.; Jurado Lucena, A.; Errasti Alcalá, B.; Poyatos Martínez, D.; Escot Bocanegra, D.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
This paper presents radar cross section (RCS) measurements of different targets suitable for electromagnetic software comparison and validation. The targets have been designed, fabricated and measured at INTA to study different scattering mechanisms such as reflection and diffraction on curved surfaces and edges (truncated cone), reflection and diffraction on planar surfaces and straight wedges (triangular prism) or tip diffraction and travelling waves (conesphere). These measurements can be used as a valuable tool to validate and adjust the input parameters of electromagnetic prediction codes according to the requirements of the engineer.
Restringido
Study of the scattering mechanisms of a set of conospheres
(Institute of Electrical and Electronics Engineers, 2010-05-12) Fernández Recio, R.; Jurado Lucena, A.; Errasti Alcalá, B.; Escot Bocanegra, D.; Poyatos Martínez, D.; Instituto Nacional de Técnica Aeroespacial (INTA)
This paper presents Radar Cross Section (RCS) measurements and predictions of a set of three conospheres suitable for electromagnetic software validation. These measurements can be used as a RCS reference data for testing existing and future codes, as well as for the analysis of the scattering mechanisms present in this kind of objects. The association between the scattering mechanism and its response is specially valuable in a validation process, in which simulations and measurements are compared, to identify the possible weak points of the electromagnetic tool.