Research On Frequency Modulated Communication Systems For New Mechanical Antennas

In modern wireless communications,signals of different frequencies are often used to communicate according to demand.Compared to low-frequency communication waves,high-frequency communication has the advantages of high transmission rate,large communication bandwidth,low delay and low communication cost,which can meet the needs of most commercial and civil communication fields.However,in special environments such as underground and buildings,high frequency electromagnetic waves have small wavelengths and propagate with a skin effect,resulting in large transmission attenuation and short transmission distances,which cannot meet the needs of normal communication for reliability,penetration and communication distance.Very low frequency(ELF)and ultra low frequency(SLF)electromagnetic waves have the advantages of strong transmission,large depth of propagation and wide range of propagation.They are a great solution to the problem of communication in special extreme environments.However,the antennas of existing ELF and SLF communication systems are bulky,complex,with low radiation efficiency,high transmitting power and energy consumption.In order to solve these problems,mechanical antenna as a mechanical movement of permanent magnets or electret directly excited electromagnetic waves of a new low-frequency electromagnetic transmission technology is proposed,in recent years,attracted a large number of domestic and foreign scholars attention.This technology is expected to break through the physical scale limitation of traditional electric short antennas and realize the portability and flexibility of low-frequency communication.In this paper,a mechanical antenna with a rotating spherical permanent magnet is proposed and the design of a matching frequency modulation communication system is completed.First of all,This paper introduces the basic concept of mechanical antenna,and analyses the physical models for four types of mechanical antennas,and studies the magnetic moments and electromagnetic radiation characteristics of rotating magnetic dipole and vibrating magnetic dipole,and deduces the propagation characteristics of electromagnetic field near field and far field of the mechanically moving magnetic dipole.Simulations were carried out in MATLAB to obtain the distribution characteristics of the electromagnetic waves radiated by the rotating dipole and to verify the feasibility of the radiated signal from the rotating magnetic dipole.Secondly,this paper compares the performance characteristics and application advantages of different types of existing mechanical antennas and their matching modulation schemes,analyses the advantages and disadvantages of each modulation scheme,designs a mechanical antenna with a rotating spherical permanent magnet for these advantages and disadvantages,and proposes a matching frequency modulation communication system.Finally,considering the modulation signal loading method and the difficulty of implementing the mechanical antenna,the feasibility analysis of the proposed frequency modulation communication system is carried out,and the communication system is optimized by combining with the actual mechanical structure,and the principle prototype of the mechanical antenna with rotating spherical permanent magnet is prepared.The proposed mechanical antenna with rotating spherical permanent magnets is validated.