An Efficient Multibeamforming Method Based on 1-bit Phase Modulation for Time-Modulated Arrays

Abstract

By using sideband signals of time-modulated arrays (TMAs), we can realize a variety of applications, including simultaneous multibeamforming and direction of arrival (DoA) estimation. However, the realization of multibeamforming with TMAs based on amplitude modulation (AM) waveform has some disadvantages. First, this method, which is based on AM waveform, results in a significant reduction in array efficiency as the number of antennas increases. Moreover, only one antenna works at a time, thus the instantaneous power is very small. In this article, a new waveform based on phase modulation (PM) is proposed to realize multibeamforming, which ensures that each antenna is always active. As a consequence, instantaneous power is improved and the theoretical value of feeding network efficiency can reach 100%, which is independent of the number of antennas. In addition, the modulated waveform proposed in this article can be optimized by genetic algorithm (GA), which further improves harmonic efficiency. As a result, this method can efficiently enhance array efficiency while reducing hardware complexity and expense. Both numerical simulation and experiment show that the proposed method is effective.