On this day, 135 years ago, on December 18, 1890 (November 7, 1890 in the lunar calendar), radio inventor Armstrong was born. Armstrong Armstrong was born on December 18, 1890. American radio inventor (inventor of superheterodyne lines). At the age of 14, inspired by G. Marconi's first radio transoceanic communication, he made many radio devices at home. Later, he entered the School of Engineering at the University of Colombia, researched three-stage transistors and designed feedback circuits that can amplify signals thousands of times. This circuit is still the heart of radio-television playback equipment. After graduation, he worked as a lecturer at his alma mater. Working at the U.S. Army's Communications Force Laboratory in Paris during World War I, he invented the superheterodyne circuit. This highly selective circuit has amplification far exceeding that of regenerative circuits and is now widely used in radio, radar and television receivers. After the war, he returned to his alma mater to serve as assistant to well-known physicist M. Popin, and later succeeded Popin as professor. He received the Gold Medal for inventing the feedback circuit and the Franklin Medal, the highest honor in the United States. The invention of broadband frequency modulation in 1933 is a new brilliant achievement and has been widely used in radio, television, microwave relay communications and satellite communications. He was ruined by defending the FM system, and committed suicide on January 31, 1951 due to his illness. He was later regarded as a great man in the world's electrical field by the International Union of Communications. The first radio station in history