The Technology Behind Radio

In the late 19th century, many scientist proposed the idea of radio. They theorized it’s possibilities, and came to conclusion that transmitting radio waves is possible. It took almost ten years before the first scientist,Guglielmo Marconi, in 1894, created the first, successful radio.

Radio’s are fairly simple, in theory. A radio station transfers material(like a song or advertisement)into radio waves. This step is called modulation. The information modulated is broadcasted through radio waves, which can be picked up by an antenna. In order to hear the sound transmitted, the radio system needs to tune in to the correct frequency or amplitude depending on the broadcast system. If it is broadcasted with variation in amplitude, then it is AM, meaning amplitude modulation, and if it is broadcasted with variation in frequency, then it is FM, frequency modulation.

I will be talking about amplitude modulation for the rest of the paper, because it was not until 1941 that FM was created. For a radio to understand the material sent, it has to understand how it was sent. A radio station sends a sine wave, called a carrier signal. It has no variation. Simultaneously, a wave with varying amplitude is sent. The two waves are then multiplied by each other, and that is the broadcast signal. The radio, then determines the amplitudes of the station, and compares that with the signal sent. This information is translated into sound, travels out a speaker, and to the ears.

Relative to FM, AM has a lower signal strength. With modulation in amplitude, some parts of the data sent may not be picked up, causing the sound to not play. It is broadcasted with a cap of 50kW. AM also operates at a lower frequency of around 535 kHz to 1605 kHz. AM waves can look similar to waves being sent by natural things, such as the sun. This can cause interference, and makes the maximum broadcasting rage limited. However, at night, when the ionosphere that the sun produces is not as prevalent, radio can transmit further distances. In conclusion, the technology that made radio possible is not as important as the implications of radio. One can now send information out to a large mass of people over long distances.

Catch a Wave: Radio Waves and How They Work