High-Efficiency and Independent Multi-Beam Scanning in Time-Modulated Arrays with Quantized Phase Modulation Sequences

Owing to the inherent multi-harmonic characteristics, a time-modulated antenna array (TMA) offers significant potential for multi-beam forming under a single radio-frequency (RF) channel. However, existing multi-beam TMAs face a trade-off between beamforming flexibility and hardware complexity, which poses challenges for high-efficiency and independent multi-beam scanning. To tackle this challenge, this work presents a novel quantized phase modulation scheme. By quantizing the continuous instantaneous phase statuses of traditional multi-beam modulation waveforms to 0°, 90°, 180°, and 270°, the proposed approach achieves high-precision, independent control of beam-pointing directions with significantly reduced complexity. Moreover, this approach avoids amplitude modulation of antenna elements, resulting in improved efficiency. On this basis, a radiation pattern synthesis strategy is developed to determine the quantized phase modulation sequences based on the desired number of beams and beam scanning angles. The proposed approach is validated through the synthesis of five independent beams using a 16-element isotropic linear array.