Heinrich Hertz, who demonstrated the existence of electromagnetic waves predicted by James Clerk Maxwell, died after a long illness in 1864 at the age of 36. In 1930 the International Electrotechnical Commission (IEC) established the hertz (Hz) as the unit of frequency. Along with other SI units, the Hertz replaced cycles per second in the United States as a partial move toward metrification.
By way of background, James Clerk Maxwell had posited, on theoretical grounds, the existence of electromagnetic waves. InA Dynamical Theory of the Electromagnetic Field（1865年），他预测电磁场以标称光速穿过太空。他将这种电磁能描述为波浪，当空气传达声波时，假定将它们携带的发光介质。麦克斯韦（Maxwell）正确地认为，光是一种类似的波浪现象，它是由相同介质的振动组成的，尽管频率不同。
麦克斯韦的工作是基于迈克尔·法拉第（Michael Faraday）几年前进行的实验。然而，麦克斯韦（Maxwell）的断言，即包括通过空间传播的波组成的电磁能，基于他开发的方程式，这是严格的理论。除光之外，还没有观察到电磁能以波的形式穿过太空。
麦克斯韦的工作被广泛接受，但截至1885年，实验确认仍然缺乏。最终，从1887年开始，赫兹建立了确认麦克斯韦的波浪传播理论的设备。该设备由发射器和接收器组成，它们之间没有直接的电连接。
In autumn, 1886, Hertz discovered that discharging a Leyden jar into one of a pair of coils would induce an electrical spark to jump across an air gap connected to the other coil. This reaction will take place in two untuned coils in close proximity. It works at a distance when the two coils are tuned to the same frequency by means of resonant circuits.
Hertz was a modest individual and asserted that his apparatus was merely a demonstration of Maxwell’s theory of electromagnetic wave propagation, with no practical application. A few years later, Guglielmo Marconi (1874-1937) was building apparatus capable of transmitting radio signals, based on Hertz’s work, at first a distance of slightly over a mile and eventually across the Atlantic from a transmitter in Canada to a receiver in Europe. If Hertz had not succumbed to a fatal illness at an early age, it is likely that he would have lived to witness his ideas give birth to commercial radio transmission.
帖子海因里希·赫兹（Heinrich Hertz）和麦克斯韦（Maxwell）的波传播理论首先出现Test & Measurement Tips.
Filed Under:Test & Measurement Tips
