Time Modulated Array Antennas: A Review

Time-modulated array (TMA) antennas, introduce the dimension of time into antenna design to control the radiation patterns and frequency spectral characteristics, thus improve the reconfigurability of array antennas and provide multiple functionalities. They have great application potential in military and civilian fields, such as precision guidance and mobile communication, and are currently a hot spot of academic research. This article provides a review on the fundamentals and applications of TMAs. First, the basic theory and mathematical formulations of TMAs are introduced. Second, the most important applications of TMAs, namely time-modulated phased arrays (TMPA), are discussed from the perspectives of harmonic suppression and harmonic utilization, which are used for single-beam and multibeam radiation. Then, we survey the combination of TMA with various types of novel antenna arrays, such as single-channel digital beamforming (DBF) arrays, frequency diverse arrays (FDAs), and retrodirective arrays, to create new hardware implementation methods and enhance their performance. Next, recent advances in dedicated integrated chips for TMA, which have played a significant role in driving the progress of TMAs from academic research to practical applications, are presented. Finally, the challenges and prospects for TMAs are discussed, including new research directions and emerging application scenarios.