中圖分類號： TN95 文獻標識碼： A DOI：10.16157/j.issn.0258-7998.201102 中文引用格式： 宋忠國，崔浩歌，席曉莉. 基于磁遮擋技術的超低頻機械天線幅度調制方法[J].電子技術應用，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，美國國防高級研究計劃局(Defense Advanced Research Projects Agency)的微系統辦公室首次提出了“機械天線(A Mechanically Based Antenna，AMEBA)”的理念，并決定在2017年8月正式啟動該項目。“機械天線”項目旨在探索一種全新的無線低頻信號發射機理，通過特殊材料，如永磁體或駐極體做機械運動來輻射低頻電磁波[3-4]。在AMEBA項目的牽頭下，多個國家的高校與科研機構開始對機械天線進行初步的探索。Akron大學的MADANAYAKE A等人首先提出并分析了電機控制永久極化偶極子做低頻機械旋轉的輻射方案，并將偶極子設計為細長圓柱體以達到最小的轉動慣量[5]。針對永磁體做高速旋轉在機械驅動上的挑戰，科羅拉多大學的GOLKOWSKI M等人提出在靜態永磁體前端增加帶有開口的導磁材料(磁快門)，驅動其旋轉循環遮蔽靜磁場來產生時變電磁場[6]。在甚低頻(3 kHz～30 kHz)頻段，美國SLAC國家加速器實驗室的KEMP M A等人提出了一種基于壓電鈮酸鋰材料進行機械振動的輻射機理[7]，其逆向利用壓電效應，往壓電材料中饋入特定頻率的交流電使其反復伸縮形變，形成振蕩向外輻射電磁波，經實驗測試，其輻射效率和帶寬比同尺寸的電小天線提高了300倍和83倍以上。
