Examinando por Autor "Montiel, I."

Mostrando 1 - 12 de 12

Restringido
Application of a Spherical Multi-Purpose Facility to the Selection of the Appropriate Radome for an On-Board POD Antenna
(Taylor and Francis Online, 2012-04-03) Poyatos Martínez, D.; Escot Bocanegra, D.; De Diego Custodio, E.; González Diego, I.; Sáez de Adana, F. M.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
This paper presents the application of a new multi-purpose facility for electromagnetic tests to the measurement of the influence of radomes on the radiation of an antenna. The antenna under test is part of a project for mounting a small, low-cost, low-power electronic system in the pod of an unmanned aerial vehicle. The shape of the radome is restricted to the pod physical specifications, but several materials could be tested to assess its effect on the antenna, and to select the best fitted for this particular application.
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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.
Acceso Abierto
Class Identification of Aircrafts by Means of Artificial Neural Networks Trained with Simulated Radar Signatures.
(The EM Academy, 2011-05-27) Jurado Lucena, A.; Montiel, I.; Escot Bocanegra, D.; Poyatos Martínez, D.; Instituto Nacional de Técnica Aeroespacial (INTA)
Non-Cooperative Target Recognition (NCTR) of aircrafts from radar measurements is a formidable problem that has drawn the attention of engineers and scientists over the last years. NCTR techniques typically involve a database with a huge amount of information from different known targets and a reliable identification algorithm able to highlight the likeness between measured and stored data. This paper uses High Resolution Range Profiles produced with a high-frequency software tool to train Arti cial Neural Networks for distinguishing between different classes of aircrafts. Actual data from the ORFEO measurement campaign are used to assess the performance of the trained networks.
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Complex permittivity estimation by bio-inspired algorithms for target identification improvement
(Springer Link, 2007-05-14) Poyatos Martínez, D.; Escot Bocanegra, D.; Montiel, I.; Olmeda, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
Identification of aircrafts by means of radar when no cooperation exists (Non-Cooperative Target Identification, NCTI) tends to be based on simulations. To improve them, and hence the probability of correct identification, right values of permittivity and permeability need to be used. This paper describes a method for the estimation of the electromagnetic properties of materials as a part of the NCTI problem. Different heuristic optimization algorithms such as Genetic Algorithms (GA) and Particle Swarm Optimization (PSO), as well as other approaches like Artificial Neural Networks (ANN), are applied to the reflection coefficient obtained via free-space measurements in an anechoic chamber. Prior to the comparison with real samples, artificial synthetic materials are generated to test the performance of these bio-inspired algorithms.
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Indoor 3D Full Polarimetric Bistatic Spherical Facility for Electromagnetic Tests
(Institute of Electrical and Electronics Engineers, 2010-08-05) Escot Bocanegra, D.; Poyatos Martínez, D.; Aguilar Rosado, Juan Angel; Montiel, I.; González, Iván; Sáez de Adana, F.; Instituto Nacional de Técnica Aeroespacial (INTA)
A new indoor facility for electromagnetic measurements has been developed and built at the Detectability and Electronic Warfare Laboratory, INTA, Spain. The system was designed to extend the previous capabilities so that not only monostatic but also bistatic radar cross section (RCS) tests could be easily conducted. Due to limited space, far-field radar cross sections in the system are restricted to small targets, but this layout will allow the researchers to investigate ReS near-field-to-far-field transformations. The system was also conceived to be versatile enough to carry out other tests, such as near-field antenna measurements, material-absorption measurements, and electromagnetic characterization of materials. The paper describes the novel concept behind the facility, and presents some preliminary measurement results on different applications.
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.
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Performance analysis of the Particle Swarm Optimization algorithm when applied to direction of arrival estimation
(Institute of Electrical and Electronics Engineers, 2009-09-18) Errasti Alcalá, B.; Escot Bocanegra, D.; Poyatos Martínez, D.; Montiel, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
Direction of arrival (DOA) estimation is a well known problem involved in different applications. The latest of these applications have greater constraints which make necessary new efforts in estimating the DOA with fewer snapshots. In that sense, this paper presents an iterative method based on particle swarm optimization that solves the problem with a single snapshot. The performance of this algorithm is analyzed and shown with numerical results under different scenarios. Conclusions are also provided.
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RCS Analysis of a Configurable Mock-Up Cavity With Blade Motion Capability
(Institute of Electrical and Electronics Engineers, 2009-02-24) Poyatos Martínez, D.; Escot Bocanegra, D.; Fernández Recio, R.; Montiel Sánchez, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
The scattering behavior and simulation of cavities are still being studied by several research groups. In this paper, a simplified jet-engine model has been manufactured and measured under different configurations, such as straight or curved blades, different fixed blades position, and free motion capability at adjustable speed. These measurements can be used to analyze the response of cavities as well as radar cross-section reference data for validating existing and future prediction codes.
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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
Spherical Indoor Facility Applied to Bistatic Radar Cross Section Measurements
(The EM Academy, 2011-09-09) Escot Bocanegra, D.; Poyatos Martínez, D.; Montiel, I.; Adana Herrero, F. M.; González Diego, I.; Instituto Nacional de Técnica Aeroespacial (INTA)
A new indoor facility for electromagnetic tests is presented and used here for the specific case of bistatic radar cross section (RCS) measurements. A metallic cube is selected as test case and the results are compared with the predictions obtained with different numerical methods. Good agreement is reported.