Co-Design and Validation Approach for Beam-Steerable Phased Arrays of Active Antenna Elements with Integrated Power Amplifiers

Journal article, 2021

An approach for designing a beam-steering active phased array of antenna elements with integrated power amplifiers (PAs) is presented. It is based on an amplifying active integrated unit cell (AiUC) concept, where the AiUC comprises a radiating slot element, a GaN high electron mobility transistor (HEMT), its input matching and DC biasing/feeding circuitry. The HEMT is embedded in the antenna element, being directly impedance-matched to HEMT’s drain output, i.e. without using any intermediate and potentially lossy impedance matching network. The proposed co-design approach involves a full-wave analysis of the AiUC passive part (naturally including elements mutual coupling effects) along with the subsequent full system harmonic balance simulations. Furthermore, we extend the standard definition of the scan element pattern (SEP) to the active scan element pattern (ASEP) that accounts for nonlinear effects of PAs on AiUC performance. We show that the ASEP is, in general, power-dependent and has a different shape as compared to the SEP. The proposed approach has been demonstrated for a K-band AiUC design example. It was verified through an active waveguide simulator, which is equivalent to the 23.7° H-plane beam-steering case. Measurements are in good agreement with simulations, revealing AiUC 47% peak drain efficiency and 33 dBm maximum radiated power. The predicted scan range is ±60° and ±37° in the E- and H-plane, respectively.