中圖分類號(hào)： TN95 文獻(xiàn)標(biāo)識(shí)碼： A DOI：10.16157/j.issn.0258-7998.201102 中文引用格式： 宋忠國(guó)，崔浩歌，席曉莉. 基于磁遮擋技術(shù)的超低頻機(jī)械天線幅度調(diào)制方法[J].電子技術(shù)應(yīng)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(guó)國(guó)防高級(jí)研究計(jì)劃局(Defense Advanced Research Projects Agency)的微系統(tǒng)辦公室首次提出了“機(jī)械天線(A Mechanically Based Antenna，AMEBA)”的理念，并決定在2017年8月正式啟動(dòng)該項(xiàng)目。“機(jī)械天線”項(xiàng)目旨在探索一種全新的無(wú)線低頻信號(hào)發(fā)射機(jī)理，通過(guò)特殊材料，如永磁體或駐極體做機(jī)械運(yùn)動(dòng)來(lái)輻射低頻電磁波[3-4]。在AMEBA項(xiàng)目的牽頭下，多個(gè)國(guó)家的高校與科研機(jī)構(gòu)開(kāi)始對(duì)機(jī)械天線進(jìn)行初步的探索。Akron大學(xué)的MADANAYAKE A等人首先提出并分析了電機(jī)控制永久極化偶極子做低頻機(jī)械旋轉(zhuǎn)的輻射方案，并將偶極子設(shè)計(jì)為細(xì)長(zhǎng)圓柱體以達(dá)到最小的轉(zhuǎn)動(dòng)慣量[5]。針對(duì)永磁體做高速旋轉(zhuǎn)在機(jī)械驅(qū)動(dòng)上的挑戰(zhàn)，科羅拉多大學(xué)的GOLKOWSKI M等人提出在靜態(tài)永磁體前端增加帶有開(kāi)口的導(dǎo)磁材料(磁快門(mén))，驅(qū)動(dòng)其旋轉(zhuǎn)循環(huán)遮蔽靜磁場(chǎng)來(lái)產(chǎn)生時(shí)變電磁場(chǎng)[6]。在甚低頻(3 kHz～30 kHz)頻段，美國(guó)SLAC國(guó)家加速器實(shí)驗(yàn)室的KEMP M A等人提出了一種基于壓電鈮酸鋰材料進(jìn)行機(jī)械振動(dòng)的輻射機(jī)理[7]，其逆向利用壓電效應(yīng)，往壓電材料中饋入特定頻率的交流電使其反復(fù)伸縮形變，形成振蕩向外輻射電磁波，經(jīng)實(shí)驗(yàn)測(cè)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。
