A Scalable Large-Array M-QAM Direct-RF Transmitter Topology With Integrated Physical Layer Security—A Proof of Concept

作者：Yasser Bigdeli, Pascal Burasa, Ke Wu · 发表于：IEEE Transactions on Microwave Theory and Techniques · 年份：2025 · DOI：10.1109/tmtt.2025.3632624 · 被引用次数：1 · 研究领域：Antenna Design and Optimization、Advanced Power Amplifier Design、Full-Duplex Wireless Communications

This article introduces a transmitter (TX) array topology that employs QPSK direct-RF TX units for realizing scalable large-array wireless communication and multifunction systems. By leveraging spatial power combination, the TX units are set to synthesize an extended M-QAM constellation, enabling flexible and high-order modulation. The QPSK modulation, when transmitted in an array, bolsters physical layer security by confining the constellation retrieval to the intended radiation angle, exhibiting high selectivity. Additionally, its low-dynamic-range (DR) waveform supports high-power output and improves the efficiency of power amplifiers (PAs) compared to higher-order constellations, thus significantly enhancing the array’s overall power–performance ratio. A comprehensive analysis is conducted on key performance factors, including location-dependent antenna gain variations, beamforming effectiveness, and phase front flatness. To validate the proposed technique, a$2\times 4$array proof-of-concept (PoC) implementation is presented. Measurement results demonstrate robust performance across modulation orders ranging from 16-QAM to 256-QAM, aligning with theoretical predictions. This topology effectively integrates spatial constellation formation with the requirements of large-array systems, offering superior power efficiency. Its scalable building blocks, reconfigurability, and inherent secure communication capabilities make it a strong candidate for next-generation high-data-rat...