中图分类号： TN95 文献标识码： A DOI：10.16157/j.issn.0258-7998.201102 中文引用格式： 宋忠国，崔浩歌，席晓莉. 基于磁遮挡技术的超低频机械天线幅度调制方法[J].电子技术应用，2021，47(5)：126-130，134. 英文引用格式： Song Zhongguo，Cui Haoge，Xi Xiaoli. Amplitude modulation method of super-low frequency mechanical antenna based on magnetic shielding technology[J]. Application of Electronic Technique，2021，47(5)：126-130，134.
Amplitude modulation method of super-low frequency mechanical antenna based on magnetic shielding technology
Song Zhongguo，Cui Haoge，Xi Xiaoli
School of Automation and Information Engineering，Xi′an University of Technology，Xi′an 710048，China
Abstract： Mechanical antenna is a new radiation mechanism that uses magnetic(polar) materials to radiate low-frequency signals, which is expected to solve the problems of large volume, high power consumption and low efficiency of existing low-frequency electrical antennas. In recent years, frequency modulation, which is widely used in the research of mechanical rotary transmitting antenna, has limitations in mechanical drive. This paper proposes a super-low frequency(30～300 Hz) mechanical antenna amplitude modulation method based on magnetic shielding technology, which separates radiation and modulation and performs them independently. The modulator controls the attenuation of the total field propagating outward through the states "open" and "closed" to realize amplitude modulation. Three-axis orthogonal coils are used to receive signals with different polarization directions. The characteristics of electromagnetic field generated by rotating permanent magnet are analyzed, the modulation is simulated, and an experimental prototype is built to verify the feasibility of the proposed method. The experimental results show that the information modulation does not need the permanent magnet to change the rotating speed frequently, thus overcoming the mechanical challenge faced by the frequency modulation of the rotary transmitting antenna.
Key words : super-low frequency；mechanical antenna；rotating permanent magnet；amplitude modulation
2016年12月，美国国防高级研究计划局(Defense Advanced Research Projects Agency)的微系统办公室首次提出了“机械天线(A Mechanically Based Antenna，AMEBA)”的理念，并决定在2017年8月正式启动该项目。“机械天线”项目旨在探索一种全新的无线低频信号发射机理，通过特殊材料，如永磁体或驻极体做机械运动来辐射低频电磁波[3-4]。在AMEBA项目的牵头下，多个国家的高校与科研机构开始对机械天线进行初步的探索。Akron大学的MADANAYAKE A等人首先提出并分析了电机控制永久极化偶极子做低频机械旋转的辐射方案，并将偶极子设计为细长圆柱体以达到最小的转动惯量[5]。针对永磁体做高速旋转在机械驱动上的挑战，科罗拉多大学的GOLKOWSKI M等人提出在静态永磁体前端增加带有开口的导磁材料(磁快门)，驱动其旋转循环遮蔽静磁场来产生时变电磁场[6]。在甚低频(3 kHz～30 kHz)频段，美国SLAC国家加速器实验室的KEMP M A等人提出了一种基于压电铌酸锂材料进行机械振动的辐射机理[7]，其逆向利用压电效应，往压电材料中馈入特定频率的交流电使其反复伸缩形变，形成振荡向外辐射电磁波，经实验测试，其辐射效率和带宽比同尺寸的电小天线提高了300倍和83倍以上。
