We explain what radio is, how it works and the types that exist. Also, what are its characteristics and why is it important.
What is radio?
Radio is a concrete application of a major technology, known as radio communication. This technology is used, for example, by merchant ships or warplanes to send and receive signals on an open frequency. But specifically, radio is the civil, informational and entertainment use of radio communication.
Radio technology consists of the transmission of signals of certain types of electromagnetic waves. By modulating them, their frequency or amplitude is altered and thus these waves transmit information, traveling from the transmitter to the receivers. They can then be converted into electrical impulses, which in turn are transformed into audible sounds.
We should not confuse what refers to radio with the chemical element radium (Ra)nor to the geometric concept of radius (of a circumference). However, its name comes directly from the first case, since a small stone of this element was used in the manufacture of the first devices.
See also: History of television
Discovery of electromagnetic waves
James C. Maxwell discovered electromagnetic waves in the 19th century and how they were generated, observing that variable electric fields created variable magnetic fields and vice versa. In 1873, Maxwell presented the results of his experiences in this regard in the previous decade before the Royal Society of London, and this was the first antecedent of radio.
Heinrich R. Hertz confirmed Maxwell’s theories in 1888.He discovered how to artificially create such electromagnetic waves and how to detect them, using a device of his own making that used two metal bars of the same size, aligned and ending in metal balls, into each of which were injected electrons at very high voltage extracted from the other.
Using this device, Hertz He demonstrated that waves could be reflected, deviated, polarized, etc. This was because they moved at a speed close to that of light, and had similar characteristics to it (wave characteristics). This was the foundation for sending radio signals.
In homage to its discoverer, These waves are called “Hertzian waves””. The name “radio” began to be used only 20 years later. Many scientists and inventors, such as Nikola Tesla or William Crookes, studied this new phenomenon and proposed applications and uses. Some already perceived the potential it would have in telecommunications.
The first transmission of hertzian waves took place on Christmas Eve 1906with a high-frequency electromagnetic alternator that generated amplitude modulated (AM) waves and transmitted the voice of Reginald Aubrey Fessenden singing a Christmas carol from Brant Rock Station, Massachusetts.
invention of radio
The first radio in history It was invented at the beginning of the 20th century, but its authorship is disputed between the Serbian Nicola Tesla and the Italian Guglielmo Marconi. The latter is known to have built the first commercially successful complete wireless telegraphy system, transmitting Hertzian waves through the air.
However, It is believed that the radio itself was an invention of Tesla which, through a legal dispute, was taken away from him by Marconi, who demanded compensation from the US government for having used his technology during the First World War without paying patent rights.
However, later inventions during the first half of the century such as the triode (electric amplification valve)wave modulation valves or the superheterodyne allowed the use of radio as we know it.
Among the first entertainment broadcasts was the one made in Argentina in 1920, with the opera Parsifal by Richard Wagner, transmitted from the roof of the Coliseo Theater in Buenos Aires.
history of radio
The history of modern radio is fruit of numerous technological convergencessuch as the discovery of Frequency Modulation (FM) as a replacement for Amplitude Modulation (AM) in 1933, the use of transistors in radios in 1950, and a number of other considerable improvements.
Radio revolutionized the world of communications and entertainment and paved the way for the arrival of television in 1948, using similar transmission mechanisms.
From then on, the radio slowly lost ground in front of televisionbeing used in the military field through special channels, or through LORAN, the first radio navigation system. The next step, the digitalization of radio, took advantage of the new technologies that the Internet made possible in the latter part of the 20th century.
On the other hand, The influence of satellites added quality, speed and power to the radio, among other new possibilities. Nowadays radio over the Internet is very common, as well as radio transmission between radio amateurs or local use for walkie-talkies.
How does the radio work?
Radio It works like any communication mechanism, intermediating between a sender and one or more receivers, which do not share a location, and communicate without seeing each other, thanks to the transmission of electromagnetic waves in the air. Such communication can be reciprocal only in certain cases in which the sender and receiver exchange their roles in turns.
A radio receiver is a device that uses an antenna to capture electromagnetic waves at a certain amplitude and frequency. From these, it obtains a minimum electrical charge that is filtered and separated by the electrical circuit inside the device, managing to distinguish between different wave frequencies (each assigned to a radio station, normally).
Finally, the electrical charge is transmitted to a speaker or loudspeaker which converts it into sound waves perceptible to the ear.
On the other hand, An issuer operates in a similar but inverse mannerA radio transmitter captures sound waves using a microphone, converting them into a series of electrical impulses that are emitted as a series of electromagnetic waves at a given frequency and amplitude.
These waves They start from the transmitting antenna and move in the air or space in all directions and at a speed very close to that of light.
Types of radio
There are three types of radio receivers:
- AM receiver. Amplitude Modulated receivers are the simplest and cheapest, and are used for radio, communications at airports or for commercial entertainment purposes, although their frequency ranges between 500 to 1700 kHz. It is easy to decode and consists of a stable variation in the amplitude of wave currents, as its name indicates.
- FM receiver. Frequency Modulated receivers work with the frequency of the waves, instead of their amplitude, which provides numerous advantages, such as greater fidelity or the possibility of eliminating unwanted signals, since the amplitude is constant in the waves. Most commercial open use signals are of this nature.
- AUB receiver. Introduced when digital audio transmission became possible, this is the most innovative type of receiver, using a single frequency network, with high quality sound signals and compensation for environmental distortions.
Radio broadcasts
Radios from different cities and countries They are constantly sending messagesthroughout a programming grid that varies according to the interests and profiles of the broadcasters, like any other media.
Each communicative segment is called issue and it is usually live, that is, happening instantly. However, at the same time they are usually recorded and played back later to give the public another opportunity to listen to them.
Each broadcast has a responsible teamwhich includes radio technicians, musicians and announcers. In many cases there are guests, phone calls that are linked to the content of the broadcast, and other radio resources.
Radio genres
There are several types of radio broadcasts depending on their content:
- Journalistic or informative. Those that seek to inform, transmit messages of importance to listeners or content that may be of interest, such as reports, chronicles, latest news, debates, interviews, etc.
- Of entertainment. Those that offer various branches of non-journalistic programming, such as music, radio soap operas, etc.
Importance of radio
Radio revolutionized the world of communications forever with a new “wireless” technology, that is, without cables of any kind, transmitted through the air and even in the vacuum of space. Thus he supplanted the telegraph and its derivatives. The commercial, military and practical applications of this were and are very numerous.
Furthermore, the invention of radio paved the way for other equally revolutionary inventionssuch as television or Wi-Fi Internet transmission, or radiolocation and radar.
Internet Radio
Internet radio is a recent phenomenon, but highly demandedThere are numerous digital stations that transmit to any device connected to the computer network (cell phones, computers, etc.).
In some cases, They allow the downloading of their broadcasts to listen to later. Among these types of emissions, the podcastsradio programs recorded in the traditional way, but designed to be listened to later.
Main international radio stations
Some of the main international radio stations in the world are:
- BBC London (England)
- Radio France International (France)
- Spain Radio International (Spain)
- China Radio International (China)
- ABC Radio – Dig (Australia)