On the Power and Beam Dependency of Load Modulation in mmWave Active Antenna Arrays

Alberto Brihuega, Matias Turunen, Lauri Anttila, Thomas Eriksson, Mikko Valkama

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Linearization of active antenna arrays is gaining increasing interest due to their wide applicability in 5G New Radio (NR) networks. As direct access to the output ports of the power amplifiers (PAs) in highly integrated millimeter-wave (mmW) active arrays is difficult, different over-the-air (OTA) digital predistortion (DPD) solutions have been recently proposed. Large majority of such solutions build on the assumption that the nonlinear behaviors of the parallel PA units are independent of the beam direction. However, in this paper, we show through comprehensive OTA measurements on a commercial 64-element active array operating at 28 GHz, that the nonlinear distortion characteristics and the involved load modulation phenomenon largely depend on the beam direction as well as on the considered transmit power, and also that the beam-dependence increases with increasing transmit power. The findings of the measurements are also connected to the state-of-the-art PA models, paving the way towards the development of more efficient DPD solutions and the associated parameter learning methods for mmW active antenna array transmitters.

Original languageEnglish
Title of host publication2020 50th European Microwave Conference, EuMC 2020
Number of pages4
ISBN (Electronic)9782874870590
Publication statusPublished - 2021
Publication typeA4 Article in conference proceedings
EventEuropean Microwave Conference -
Duration: 12 Jan 202114 Jan 2021

Publication series

Name2020 50th European Microwave Conference, EuMC 2020


ConferenceEuropean Microwave Conference


  • 5G NR
  • digital predistortion
  • millimeter-waves
  • phased arrays
  • power amplifiers
  • RF measurements

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Instrumentation


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