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Ever wondered how a radio works? You know, the thing your parents turn on in the car when they can’t get their phone’s bluetooth to connect? Maybe good ol’ fashioned radio isn’t as impressive nowadays as Smart phones, Wi-Fi, or smart home devices-- but it’s one of the most important technological breakthroughs of the 19th century, and without it, many of our favorite daily use technologies of the 21st century never could have been developed.
So, let’s start with the basics. A radio broadcast is sent from a radio station to the terrestrial radio in your parent’s car by an electromagnetic wave we call a Radio Frequency. This RF is used to send the signal through the atmosphere and forms the basis for how radio (and television) work when coming in from local, terrestrial stations. So it’s radio frequencies you have to blame for your parent’s NPR habit. The radio frequency band is from around 3 kHz to about 300 GHz (the k means thousand and the G means billion; the Hertz means cycle per seconds; thus the RF is Oscillating at from 3,000 cycles per second to about 300 billion cycles per second-- that’s a lot of cycles!). The RF band is only one band of the Electromagnetic Spectrum, which also includes visible light, microwaves, infrared, ultra light, x-ray, and gamma rays (you know, the things that created the Hulk). RF is really a special form of a Light Ray (or photons), and we’ve discovered many uses for it. Television and radio are the most obvious examples, but there are many other uses for RF including in medicinal and defense technologies (Medical Resonance Imaging and access denial, for instance); general radio use such as the police band or the citizens band; shortwave radio; in smart phones and other phone communication technologies; and many computer uses (including Wi-Fi). RF was first predicted by James Clark Maxwell in a paper from 1864 which showed equations describing the electromagnetic spectrum. The first person to prove that radio waves did exist was Heinrich Hertz, a German scientist between 1885 and 1889. Hertz wrote a book describing his findings that was published in 1892 which led the way to many of the RF uses we enjoy even today. Radio waves were used by Guglielmo Marconi in 1895 to transmit the first wireless signal in Italy. The first transoceanic radio wave was submitted by Marconi later in 1895 and led to the use of radio by ships to communicate with other ships and to transmit emergency signals when necessary. An American, Lee Forrest, developed technology that allowed the enhancement of the radio signal to receivers that resulted in AM (or Amplitude Modulation) radio. FM radio was later essentially invented by another American, Edwin Howard Armstrong, which remains the most popular band for terrestrial radio today. Smart phones. Wi-Fi. Emergency bands. Global communications. All of these game changing technologies are thanks, in whole or in part, to radio frequency-- as far as I’m concerned, a much unsung hero of the human race. |
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GLOSSARY
Amplitude Modulation the modulation of a wave by varying its amplitude, primarily used as a means of radio broadcasting, in which an audio signal combines with a carrier wave.
Electromagnetic Spectrum the range of wavelengths over which electromagnetic radiation extends over.
Light Ray or Photons a particle that represents a quantum of light or other electromagnetic radiation.
Oscillating vary in magnitude or position in a regular way about a central point.
Radio Frequency radio frequency refers to an oscillation rate of an alternating electric current of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around twenty thousand times per second to around three hundred billion times per second.
Electromagnetic Spectrum the range of wavelengths over which electromagnetic radiation extends over.
Light Ray or Photons a particle that represents a quantum of light or other electromagnetic radiation.
Oscillating vary in magnitude or position in a regular way about a central point.
Radio Frequency radio frequency refers to an oscillation rate of an alternating electric current of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around twenty thousand times per second to around three hundred billion times per second.
