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引言 1865年麦克斯韦尔提出了位移电流,但未能证实位移电流的存在,1887年赫尔在次级回路中观察到放电,从而证明了位移电流和电磁波的存在。电磁波的应用开始于马可尼的工作,1895年他在一英里的距离上发送了电报信号,1898年电报信号第一次被送过英伦海峡。那时用的是衰减波,接受信号也无法放大,直到1906年三极管问世,才具备了等幅波振荡和放大信号的手段。从那以后,随着国际形势的不断变化和科学技术的不断发展,使电磁波的应用不
INTRODUCTION Maxwell proposed a displacement current in 1865, but failed to confirm the existence of a displacement current. In 1887, Hull observed a discharge in the secondary circuit, demonstrating the existence of displacement currents and electromagnetic waves. The application of electromagnetic waves began with Marconi’s work, in 1895 he sent telegraph signals over a distance of one mile, and the telegraph signal was sent to the Channel of England for the first time in 1898. At that time, the attenuation wave was used and the signal was not amplified. Until the advent of the transistor in 1906, it had the means of oscillating and amplifying the signal of equal amplitude. Since then, with the ever-changing international situation and the continuous development of science and technology, the application of electromagnetic waves