Novel low-frequency antennas: recent progresses

Development and major breakthroughs in the study of low-frequency antennas are reviewed in this paper． Persistent challenges are presented of traditional low-frequency antennas (large size, low efficiency, and narrow bandwidth), focusing on two core technologies of mechanical antennas and coil-based magnetic induction antennas, to analyze and summarize working principles of solutions for various novel low-frequency antennas． Key technologies aimed at improving radiation efficiency and antenna bandwidth are discussed． Roles and applications of core components are analyzed． Technical challenges confronting novel low-frequency antennas are discussed, as well as future development directions． This review will provide some reference for scientific research and engineering design in the field．