Mechanical Antennas: Emerging Solution for Very-Low Frequency (VLF) Communication

Analysis of Transmission Characteristics on an MSK-Based Rotating Magnet-Based Mechanical Antenna

“…e corresponding rotation angular velocity is Ω 1 ∼Ω 2 at t 1 ∼t 1 + Δt r . For the drive characteristics of PMSM, T em is constant [30], since T em ≫ (R Ω + R rad )Ω, dΩ/dt is approximately a constant from equation (1). Hence, the transient process of the speed step change can be regarded as a linear variation, and the times reaching stable performance are Δt r and Δt f , respectively (ignoring the oscillation process).…”

“…Super-low frequency (SLF, 30-300 Hz) waves have the characteristics of long propagation distance and good seawater penetration, which have great potential for applications in the eld of underwater communication [1][2][3][4]. However, the low-frequency electromagnetic transmitting antennas of existing technologies are all electrically small antennas (ESAs), which rely on the oscillating current in the conductor to excite electromagnetic waves.…”

Propagation Characteristics and Magnetic Field Distribution of Rotating Magnet-Based Mechanical Antenna in the Air-Seawater-Seabed Three-Layer Medium

“…Low-frequency electromagnetic wave has the characteristics of good seawater penetration and long propagation distance [1][2][3][4], which can be used to realize cross-media wireless communication. Te existing low-frequency transmission system has problems such as large antenna volume, low radiation efciency, and high energy consumption, which restricts its application and development in related felds.…”

Analytical model of magnetic torque of rotating permanent magnet mechanical antenna array

“…Low-frequency communication system, the lower the center frequency of the electrical antenna physical size, so the existing low-frequency communication system has a large transmitter scale, power consumption is too large problems. These factors seriously limit the development of low-frequency communication systems, in order to solve the existing problems of low-frequency communication systems, the U.S. Defense Advanced Research Agency proposed the "mechanical antenna" project, which will explore a new signal generation and radio transmission mechanism, through the mechanical vibration of permanent magnets or electret to generate signals to achieve ultra-low frequency radio waves emission [1], the same year James A. Bickford et al of the U.S. Hardware Design and Development Agency proposed the concept of an electromagnetic transmitter [2], the following year Navid Barani and Kamal Saraband et al of the Department of Electrical Engineering and Computer Science at the University of Michigan theoretically derived the radiation of rotating dipole charges and rotating magnets [3], followed closely by Hunter C. Burch et al of Florida State University verified experimentally in 2018 that a time-varying magnetic field can be generated in the ELF band when a permanent magnet is rotated to the desired frequency [4], demonstrating the feasibility of mechanical antennas for proximity communication, based on which the teams of Zhang Duo of Xi'an University of Technology [5] and Cui Yong of Beijing University of Aeronautics and Astronautics [6] demonstrated through simulations that even with the The electret type mechanical antenna radiation intensity is about 20% smaller than the permanent magnet type mechanical antenna under the same physical parameters and environmental conditions, thus the permanent magnet type mechanical antenna has become the focus of the current mechanical antenna research, and the research direction of each unit has started the research of various aspects for the rotating permanent magnet antenna. For example, Hossein Rezaei et al in the EMC laboratory of Missouri University of Science and Technology, Rolla, USA, designed a method to generate amplitude shift keying (ASK) modulated signals using a modulating coil [7], and also derived a circuit model and analytical formula for the modulation efficiency of the generator, and verified that the performance of the excitation generator designed by this model is better than that of the conventional coil source (at the same volume and The excitation strength is 23 dB for the same volume and dissipated power of 0.35 W).…”