Study and Analysis of a Multilayer Multipair Electret-Based Thin-Film Mechanical Antenna

K P Zhou,Y T Niu,Z D Wang,Z Wang,W N Liu,S H Guo,B Li,X K Zhao,Stefano Selleri

doi:10.1155/2021/3646425

K P Zhou, Y T Niu + Show 7 more

Open Access

https://doi.org/10.1155/2021/3646425

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Abstract

Very low-frequency (VLF) and ultralow-frequency (ULF) electromagnetic waves have the advantage of high penetration and low propagation loss in wireless communication systems and are mainly used for underwater and underground communications, as well as for earthquake and lightning forecasting. At present, VLF and ULF antennas are mostly bulky and require hundreds of antennas and more to be set up, which is costly and inefficient. In this paper, we propose to generate VLF and ULF signals by rotating a multilayer multipair electret thin-film electret driven by an excitation device, which improves the problem of low radiation efficiency of VLF and ULF signals and the large size of conventional low-frequency transmitting antennas. Based on a multilayer, multipair electret film mechanical antenna, a magnetic field propagation model is developed, and the relationship between the magnetic flux density mode and the number of layers of electret films, as well as the relationship between the antenna emission frequency and the motor rotation frequency and the number of pairs of electret films, is analyzed. The selection of a suitable model for practical situations based on conditions such as antenna size and propagation distance is illustrated. The research work is of great importance for guiding the design of mechanical antennas and optimizing antenna structures.

Highlights

High-frequency wireless communication has the advantages of large bandwidth, fast communication rate, and low latency; compared to high-frequency wireless communication, the low-frequency electromagnetic wave has the characteristics of high communication reliability, strong penetration, and longer communication distance
When electromagnetic waves are propagated in other media such as water and underground, high-frequency electromagnetic waves will attenuate very quickly, resulting in poor communication quality in other media such as underwater and underground, while very low-frequency and ultralow-frequency electromagnetic waves can propagate over longer distances in other media such as underwater and underground due to their excellent penetration [1]
Reference [3] proposed a Very low-frequency (VLF) (Very Low-Frequency) transmitter based on a piezoelectric crystal, the scheme used adds AC to the two ends of the piezoelectric crystal, the piezoelectric crystal is machined into a quadrilateral shape, when an electrical signal is added to the two ends of the crystal, the crystal will stretch and deform according to the law of the added electrical signal, the reciprocal stretch and deformation belong to mechanical vibration, and the mechanical vibration of the piezoelectric crystal will generate a changing electromagnetic field around it [3]

Summary

Introduction

High-frequency wireless communication has the advantages of large bandwidth, fast communication rate, and low latency; compared to high-frequency wireless communication, the low-frequency electromagnetic wave has the characteristics of high communication reliability, strong penetration, and longer communication distance. Changing the charge distribution pattern by varying the number of layers and pairs of electret films brings great possibilities to change the radiation frequency and increase the propagation distance of mechanical antennas, which brings great possibilities to the research of mine communication, submarine communication, and wearable low-frequency transmitting antennas. Where β arctan(y/x), and φ arccos(cos 2 β + 1/2) It can be seen from equation (9) that when ignoring the effect of antenna size, the magnetic x − y induction vector mode at any point in the plane varies with time according to the cosine function, and the maximum value of the magnetic induction mode at the same distance to the source D is the same. ⎛⎜⎜⎝􏽱 ω z R c o s θ , 􏽱− ω z R s i n θ , 􏽱 ω y R s in θ − 􏽱ω x R c o s θ ⎞⎟⎟⎠, x2 + y2 + z2 x2 + y2 + z2 x2 + y2 + z2 x2 + y2 + z2 z ω

B Figure 4

Numerical Simulation of a Cylindrical Electret Mechanical Antenna

Attenuation of Electret-Type Mechanical Antennas in Different Media

Conflicts of Interest