Single-Channel Digital Beamforming With Frequency Diversity Single-Sideband Time-Modulated Arrays

• Published in: IEEE transactions on microwave theory and techniques pp. 1 - 13
• Main Authors: Luo, Deng-Yue, Zhang, Jin-Dong, Chen, Qiao-Yu, Wu, Wen, Fang, Da-Gang
• Format: Journal Article
• Language: English
• Published: IEEE 2025
• Subjects: Digital beamforming (DBF); frequency diversity; nonuniform period modulation (NUPM); single-sideband time-modulated array (STMA)
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2025.3582802

This article presents a single radio frequency (RF) channel architecture with frequency diversity to implement digital beamforming (DBF). By converting the time-domain switching characteristics into frequency-domain diversity, the signals received by all array elements can be transmitted by sharing a single RF channel. A single-sideband time-modulated array (STMA) with multistep in-phase/quadrature (I/Q) modulation is introduced, which concentrates the signal energy mainly in the first positive harmonic component, significantly suppressing unwanted sidebands and mitigating interference. The different modulation frequencies between the elements can be flexibly configured using a nonuniform period modulation (NUPM) strategy to achieve frequency diversity without adding hardware complexity. Compared with other DBF implementation architectures, this design significantly reduces hardware complexity while maintaining reliable signal recovery performance. Measurement results show that the baseband equivalent signals of the signals received by the array elements, including amplitude and phase distributions, can be recovered correctly and in real time. The resulting DBF-formed radiation patterns in the ±40° angular range are in good agreement with the theoretical results.