Radio's development after the invention of the vacuum tube was the beginning of electronics. Broadcast radio is 100 years old this year, if you count the very earliest unauthorized broadcasts in 1906. The first commercially licensed AM radio station was KDKA in Pittsburgh, which began broadcasting in 1920. Edwin Armstrong invented FM radio in 1933, and broadcasts began in 1937.
AM and FM broadcasting have served us well all these years, and they still do. Over 11,000 stations are licensed and on the air today. We all listen to some form of radio, no doubt mostly in our cars.
Satellite radio came along in 2002. This paid subscription digital radio system has been slow to develop. But it is now well established and growing as more car, home, and portable radios become affordable.
