• 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 ...
    • 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 ...
    • 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 ...
    • Channel Estimation and Hybrid Precoding for Frequency Selective Multiuser mmWave MIMO Systems 

      González-Coma, José P.; Rodríguez-Fernández, Javier; Gonzalez-Prelcic, Nuria; Castedo, Luis; Heath, Robert W. (IEEE, 2018-05)
      [Abstract]: Configuring the hybrid precoders and combiners in a millimeter wave multiuser multiple-input multiple-output system is challenging in frequency selective channels. In this paper, we develop a system that uses ...
    • 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, ...
    • Impact of Time-Modulated Arrays on the BER of Linear Digital Modulations 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Taylor & Francis, 2015-08-21)
      [Abstract] Time modulation provides a simple way to control the power radiation pattern of an antenna array. By appropriately selecting the parameters of a Time-Modulated Array (TMA) it is possible to obtain a reconfigurable ...
    • Low-Complexity Distance-Based Scheduling for Multi-User XL-MIMO Systems 

      González-Coma, José P.; Lopez-Martinez, F.J.; Castedo, Luis (IEEE, 2021-11)
      [Abstract]: We introduce Distance-Based Scheduling (DBS), a new technique for user selection in downlink multi-user communications with extra-large (XL) antenna arrays. DBS categorizes users according to their equivalent ...
    • Optimizing Uniformly Excited Linear Arrays through Time Modulation 

      Fondevila, J.; Brégains, Julio; Ares Pena, F. J.; Moreno Piquero, E. (Institute of Electrical and Electronics Engineers, 2004-12)
      [Abstract] The letter shows that, by the proper use of time modulation in equispaced linear arrays with uniform excitation distribution, it is possible to maintain the sidelobe zone of the radiated power below a certain - ...
    • Performance Analysis of Time-Modulated Arrays for the Angle Diversity Reception of Digital Linear Modulated Signals 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis; Rocca, Paolo; Poli, Lorenzo (Institute of Electrical and Electronics Engineers, 2017)
      [Abstract]: Diversity occurs whenever several copies of the same transmitted signal arrive at a receiver. Such a situation allows for improving the performance of a wireless communication system transmitting over a radio ...
    • Perturbation of the Phases of Taylor Field Samples in the Synthesis of Linear and Circular Array Antennas 

      Brégains, Julio; Ares Pena, F. J.; Roederer, A. G. (Institute of Electrical and Electronics Engineers, 2004-12)
      [Abstract] Antenna design specifications do not usually restrict the phase of the radiated field. Antenna synthesis techniques generally exploit this freedom only indirectly, but direct phase perturbation can be fruitful.
    • Rank Constrained Precoding for the Downlink of mmWave Massive MIMO Hybrid Systems 

      González-Coma, José P.; Fresnedo, Óscar; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2021-02-11)
      [Abstract] The hybrid design of precoding schemes for millimeter-wave communications allows exploiting the gains by using large antenna array with an affordable hardware cost and power consumption. In this work, we present ...
    • Robust Precoding with Bayesian Error Modeling for Limited Feedback MU-MISO Systems 

      Joham, Michael; Castro-Castro, Paula-María; Castedo, Luis; Wolfgang, Utschick (IEEE, 2010)
      [Abstract] We consider the robust precoder design for multiuser multiple-input single-output (MU-MISO) systems where the channel state information (CSI) is fed back from the single antenna receivers to the centralized ...
    • Time Modulated Arrays: from their Origin to Their Utilization in Wireless Communication Systems 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (M D P I AG, 2017-03-14)
      [Abstract] Time-modulated arrays (TMAs) are electromagnetic systems whose radiated power pattern is controlled by the application of variable-width periodical pulses to the individual elements. The nonlinear nature of the ...
    • Time-modulated array beamforming with periodic stair-step pulses 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Elsevier, 2020-01)
      [Abstract]: Time-modulated arrays (TMAs) are able to improve the side-lobe level of the radiation pattern at the fundamental mode but cannot steer the beam at such a mode towards a given direction. Beam-steering is possible ...
    • Time-Modulated Phased Array Controlled With Nonideal Bipolar Squared Periodic Sequences 

      Maneiro-Catoira, Roberto; Brégains, Julio; García-Naya, José A.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2019-02)
      [Abstract]: Bipolar (±1) sequences with no zero state suit particularly well for safeguarding the switched feeding network efficiency when applied to time-modulated arrays. During the zero state of a conventional time-modulating ...
    • Variation in The Bandwidths of Pattern-Quality Parameters and Maximum Embedded Impedance among the Solutions to Shaped-Beam Synthesis Problems for Collinear Dipole Arrays 

      Brégains, Julio; Ares Pena, F. J.; Moreno Piquero, E. (Institute of Electrical and Electronics Engineers, 2003)
      [Abstract] We investigated variation in the bandwidths of ripple, sidelobe level, -3 dB beamwidth, and maximum element embedded (active) impedance (|Z/sup e/|/sub max/) among multiple collinear dipole arrays radiating a ...
    • Very Fast Method to Synthesise Conformal Arrays 

      Fondevila, J.; Rodríguez, J. A.; Brégains, Julio; Moreno Piquero, E.; Ares Pena, F. J. (The Institution of Engineering and Technology, 2007-08-02)
      [Abstract] A very fast technique that allows the synthesising of arbitrary footprint patterns by using conformal arrays with many radiating elements is described. This method is based on a combination of Woodward-Lawson ...
    • Wideband Hybrid Precoding Using Time Modulated Arrays 

      González-Coma, José P.; Castedo, Luis (Institute of Electrical and Electronics Engineers, 2020-08-05)
      [Abstract] Hybrid digital-analog precoding is a cost effective solution for transmitting over the large bandwidths and huge antenna arrays available in the millimeter wave frequency bands. In this work we focus on the ...