Power Efficiency and Linearity of Highly Integrated Transmitting Array Antennas

Energy efficiency of 5G communication networks and beyond is a major challenge that is yet solved due to high power consumption and low linearity of massive array transmitters. This paper contributes to the existing framework of research in this area—that is today mainly dominated by the RF-component level and algorithmic solutions—by investigating various possible design trade-offs for highly-integrated active antenna elements as employed in such array transmitters. We demonstrate how to exploit antenna element design to synthesize the optimal loading conditions of a given power amplifier (PA) to, e.g., maximize its power-added efficiency (PAE), minimize nonlinear behavior, or find the desired trade-off between both. The numerical example with a K-band PA-integrated antenna element illustrates that moderate nonlinear effects of the PA can be significantly reduced (with up to 10–20 dB in third-order intermodulation distortion) by tuning the antenna design, with a relatively small PAE loss (< 5%). The effects of antenna array mutual coupling and corresponding cross-talk between PAs when beamsteering are discussed for a small-scale linear array of such elements.