Listar Grupo de Tecnoloxía Electrónica e Comunicacións (GTEC) por autor "Brégains, Julio"

Mostrando ítems 1-20 de 50

    • A Comparison of Optimization Techniques for Power Patterns with Low Sidelobes Generated by Linear Arrays with Efficient Excitation Distributions 

      Smith, S. Kyle; Brégains, Julio; Kathleen, L. Melde; Ares Pena, F. J. (John Wiley & Sons, Inc., 2005-04-05)
      [Abstract] Equispaced linear arrays that have uniformly excited central elements and monotonically decreasing flanking segments have been shown to yield low-sidelobe patterns with specified constraints on the effective ...

    • A MATLAB Interface for Analyzing Conformal Arrays Composed of Polarized Heterogeneous Elements 

      Brégains, Julio; García-Naya, José A.; González-López, Miguel; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2011-10)
      [Abstract] As an extension and improvement of a previous work, this paper presents a graphical interface designed with MATLAB®, which is capable of representing both the spatial and electrical configurations of a conformal ...

    • A MATLAB Tool for Visualizing the 3D Polar Power Patterns and Excitations of Conformal Arrays 

      Brégains, Julio; García-Naya, José A.; González-López, Miguel; Dapena, Adriana (Institute of Electrical and Electronics Engineers, 2010-08)
      [Abstract] This paper describes the implementation of a MATLAB® tool to plot the three-dimensional polar radiation diagram generated by a conformal antenna array. A related tool has also been developed for visualizing the ...

    • A TMA-FDA Approach for Two-Beam Steering 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2021)
      [Abstract]: Frequency diverse arrays (FDAs) allow the synthesis of dot-shaped radiated patterns in the range-angle space by applying frequency offsets to the antenna elements. Conventional FDAs are usually implemented with ...

    • A WiMAX Conformal Broad-Beam Antenna 

      Brégains, Julio; Castedo, Luis; Ares Pena, F. J. (Institute of Electrical and Electronics Engineers, 2010-12)
      [Abstract] The numerical model of a very simple conformal antenna, prepared to work in the 3.4 to 3.6 GHz WiMAX range, is presented. The pattern radiated by the proposed antenna displays high gain and excellent linear ...

    • An Experimental Set-Up for Measurement of the Power Absorbed from 900 MHz GSM Standing Waves by Small Animals, Illustrated by Application to Picrotoxin-Treated Rats 

      López Martín, E.; Brégains, Julio; Jorge Barreiro, F. Javier; Sebastián Franco, José Luis; Moreno Piquero, E.; Ares Pena, F. J. (Electromagnetics Academy, 2008)
      [Abstract] We describe an experimental set-up for exposure of small animals to radiofrequency standing waves that allows direct measurement of the power absorbed by the animal. Essentially, the set-up consists of a metallic ...

    • Analog Beamforming Using Time-Modulated Arrays With Digitally Preprocessed Rectangular Sequences 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2018-03)
      [Abstract]: Conventional time-modulated arrays are based on the application of variable-width periodical rectangular pulses (easily implemented with radio frequency switches) to the individual antenna excitations. However, ...

    • Analysis, Synthesis, and Diagnostics of Antenna Arrays through Complex-Valued Neural Networks 

      Brégains, Julio; Ares Pena, F. J. (John Wiley & Sons, Inc., 2006-08)
      [Abstract] It is shown in this paper that when artificial neural networks are extended to be complex valued, they can be incorporated as a very powerful and effective tool in the analysis, synthesis, and diagnostics of ...

    • Application of Time Modulation in the Synthesis of Sum and Difference Patterns by Using Linear Arrays 

      Fondevila, J.; Brégains, Julio; Ares Pena, F. J.; Moreno Piquero, E. (John Wiley & Sons, Inc., 2006-05)
      [Abstract] In this paper, time modulation is applied to a small number of elements of a linear array that radiates either sum or difference patterns, in order to take control over their sidelobe levels. The simulated ...

    • Avoiding Interference in Planar Arrays through the Use of Artificial Neural Networks 

      Brégains, Julio; Dorado, Julián; Gestal, M.; Rodríguez, J. A.; Ares, F.; Pazos, A. (Institute of Electrical and Electronics Engineers, 2002-08)
      [Abstract] This article implements an artificial neural network to find, through computer simulation, the excitations of a square planar array. The array is composed of 52 uniformly spaced subarrays, and has a quasi- in ...

    • Beam Reconfiguration of Linear Arrays Using Parasitic Elements 

      Rodríguez, J. A.; Trastoy, A.; Brégains, Julio; Ares Pena, F. J.; Franceschetti, G. (The Institution of Engineering and Technology, 2006-02-13)
      [Abstrac] An innovative method for linear arrays beam reconfiguration is presented. This pattern reconfigurability is achieved by a mechanical displacement of a parasitic array located in front of an active one. Two worked ...

    • Calculating Directivities with the Two-Dimensional Simpson's Rule 

      Brégains, Julio; Coleman, I. C.; Ares Pena, F. J.; Moreno Piquero, E. (Institute of Electrical and Electronics Engineers, 2004-08)
      [Abstract] C++ routines implementing the simple generalization of Simpson's rule to two dimensions for calculating antenna directivities compare well with methods currently available in common symbolic and numerical ...

    • Circularly Polarized Arrays of Sequentially Crossed Dipoles 

      Brégains, Julio (Genxcellence Software Pvt. Ltd., 2013-11)
      [Abstract] Usual configurations of dipoles that radiate circularly polarized fields consist of elements arranged in crossed pairs, with one component of each pair in top of the other component. As an alternative to this, ...

    • Combining Switched TMAs and FDAs to Synthesize Dot-Shaped Beampatterns 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2021)
      [Abstract]: The application of frequency offsets to the elements of a conventional phased array with variable phase shifters (VPSs) leads to frequency diverse arrays (FDAs) with the ability to provide range-angle spatial ...

    • Design of Reconfigurable Array Antennas With Minimum Variation of Active Impedances 

      Mahanti, G. K.; Das, S.; Chakrabarty, A.; Brégains, Julio; Ares Pena, F. J. (Institute of Electrical and Electronics Engineers, 2006-12)
      [Abstract] In this letter, the authors propose an optimization method based on the genetic algorithm (GA) to reconfigure a linear array of vertical half-wavelength dipole antennas to generate two patterns with minimum ...

    • Direct Antenna Frequency-Hopped M-FSK Modulation With Time-Modulated Arrays 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2024-02)
      [Abstract]: We present an innovative approach that simultaneously enables direct antenna frequency-hopped M-ary frequency shift keying (DAFH-MFSK) modulation and beamsteering through the use of time-modulated arrays (TMAs). ...

    • Dual-Beam Steerable TMAs Combining AM and PM Switched Time-Modulation 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (MDPI, 2022)
      [Abstract] Wireless sensor networks (WSN) are increasingly requiring directional antennas that not only provide higher capacity, security, transmission range or robustness against interference, but also contribute with ...

    • Dual-Signal Transmission Using RF Precoding and Analog Beamforming With TMAs 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (IEEE, 2018-06)
      [Absctract]: Time-modulated arrays (TMAs) receiving beamforming provide a noteworthy hardware simplicity given the ability of this multi-antenna technique to transform spatial diversity into frequency diversity. However, ...

    • Dual-Signal Transmission Using RF Precoding and Analog Beamforming With TMAs 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2018)
      [Abstract]: Time-modulated arrays (TMAs) receiving beamforming provide a noteworthy hardware simplicity given the ability of this multi-antenna technique to transform spatial diversity into frequency diversity. However, ...

    • Effects of Measurement Distance on Measurements of Symmetrically Shaped Patterns Generated by Line Sources 

      Brégains, Julio; Ares Pena, F. J.; Moreno Piquero, E. (Institute of Electrical and Electronics Engineers, 2003-02)
      [Abstract] Symmetrically shaped patterns, generated by real continuous linear apertures derived from Taylor distributions, resemble Taylor sum patterns in regard to the distance-dependence of their sidelobe heights. Their ...