Time-Modulated Arrays: A Review

In the modern communication era, antenna arrays play a vital role, demanding more constrained antenna arrays with high gain, ultra-low sidelobes, and other characteristics. The introduction of the fourth dimension, time in antenna arrays, reduces the effort needed for synthesis and offers flexibility in designing high-performance antenna arrays. The fourth-dimensional antenna with time as the fourth dimension is also known as Time-Modulated Antenna Array (TMAA). The modulation of the antenna array by periodic time sequence generates harmonic radiation patterns. This paper represents a review of TMAA from its evolution to the current progress. The virtue of time modulation provides multi-beam radiation from TMAA, which finds its application in numerous fields like secure communication, tracking of elements, and simultaneous scanning in azimuthal and elevation planes. The exploitation of TMAA in the fields requires synthesis of the radiation pattern, making it suitable for the application by reducing the sidelobe and sideband levels, radiating sum-difference patterns, multi-tone radiation, Wireless Power Transfer, antenna failure correction, and many more. Furthermore, TMAA with an optimized timing sequence may find a place in future generations' communication.