Research On Ultra Low Frequency Mechanical Antenna Array Based On Rotating Permanent Magnet

The transmission or penetration ability of electromagnetic waves is closely related to its own operating frequency,the magnetic permeability and electrical conductivity of the transmission medium,and other factors.In conductive media,due to the existence of skin effect,the higher the frequency,the greater the attenuation of electromagnetic wave propagation.Mechanical antenna technology is a new communication method to drive the magnetic charge source or charge source to do some variable-speed motion to produce ultra-low frequency electromagnetic field.It is conducive to solve the problems of traditional antenna in this band,such as large volume,complex impedance matching network,low radiation efficiency and high power consumption.It has a wide application prospect in long-distance communication of underwater,underground and other conductive media.The rotating permanent magnet mechanical antenna relies on the motor to drive the permanent magnet to rotate to generate time-varying electromagnetic wave.The radiation distance of a single rotating permanent magnet mechanical antenna is subject to the basic performance parameters of the antenna carrier material and the volume of the magnet,At present,the performance of Nd-Fe-B and other third-generation rare earth permanent magnet materials is close to its theoretical limit.At the same time,increasing the volume will bring huge load to the auxiliary drive system.In this paper,an array of rotating permanent magnet mechanical antenna elements is proposed.Firstly,the expression of the near-field radiation of the mechanical antenna is derived.Based on the space vector superposition method,the model of the rotating permanent magnet mechanical antenna array is established,and the expression of the time-varying magnetic field of the array is obtained;Secondly,the numerical simulation of the mechanical antenna and array is carried out to analyze the effect of the number of elements,the initial phase difference of elements and the spacing of elements on the radiation field strength,and further verify the correctness and rationality of the mechanical antenna array model through the finite element simulation;Furthermore,according to the results of numerical simulation and finite element simulation,the experimental prototype of the ultra-low frequency mechanical antenna array is built,the components of the prototype are introduced in detail,the mathematical model of coil sensitivity is established,and the correctness and feasibility of the mechanical antenna array and related theoretical results are verified by collecting the measured time-varying signals of the coil.Finally,Summarize the full paper.The design of the ultra-low frequency mechanical antenna array based on rotating permanent magnet provides a new method for increasing the field intensity coverage.It has laid a foundation for the research of mechanical antenna array.