Heinrich Hertz (1857–1894) was a German physicist who was the first person to demonstrate that electromagnetic waves existed. He designed a transmitter and receiver that produced waves with a 4-meter wavelength. He used standing waves to measure their wavelength. He showed that they could be reflected, refracted, polarized, and could produce interference. It was Hertz’s breakthroughs in electromagnetic waves that paved the way for the development of radio. In 1930 Hertz was honored by having the unit of frequency, which was cycles per second, replaced by the hertz (Hz).