Radio - Simple English Wikipedia, the free encyclopedia
Jump to content
From Simple English Wikipedia, the free encyclopedia
A radio tower
Radio is a way to send
electromagnetic signals
over a long distance. It is mainly used to deliver
information
from one place to another. A machine that sends
radio waves
is called a
transmitter
, while a machine that "picks up" the signals is called a
receiver
or antenna. A machine that does both jobs is a "transceiver". When
radio signals
are sent out to many receivers at the same time, it is called a
broadcast
Television
also uses radio signals to send pictures and sound.
Airplanes and other things may be used under
radio control
. Radio signals can be used to lock and unlock the doors in a car from a distance.
Sound
can be sent by radio, sometimes through
Frequency Modulation
FM
) or
Amplitude Modulation
AM
).
History of radio
change
change source
Many people worked to make radio possible. After
James Clerk Maxwell
predicted them,
Heinrich Rudolf Hertz
in
Germany
first showed that
radio waves
exist.
Guglielmo Marconi
in
Italy
made radio into a practical tool of
telegraphy
used mainly by ships at sea. He is sometimes said to have
invented
radio. Later inventors learned to transmit
voices
, which led to
broadcasting
of
news
music
and
entertainment
Uses of radio
change
change source
Radio was first used as a way to send
telegraph
messages between two people without wires. Voice transmission followed, which developed into broadcasting. Two-way voice radio also came into use, including
walkie-talkies
and eventually
mobile phones
Radio waves
are still used to send messages between people. Talking to someone with a radio is different than "talk radio".
Citizens band radio
and
amateur radio
use specific radios to talk back and forth.
Policemen
firemen
and other people who help in
emergency
use a radio
emergency communication system
to communicate (talk to each other). It is like a
mobile phone
, (which also uses radio signals) but the distance they reach is shorter and both people must use the same kind of radio.
The word "radio" is sometimes used to mean only voiceband
broadcasting
. Most voiceband broadcasting uses lower frequency and longer
wavelength
than most television broadcasting. Voiceband broadcasting sends
music
news
and
entertainers
including "talk radio".
Radio programs
were used before there were TV programs. In the 1930s, the US president started sending a message about the country every week to the American people. Companies that make and send radio programming are called
radio stations
. These are sometimes run by governments, and sometimes by private companies, who make money by sending
advertisements
. Other radio stations are supported by local communities. These are called community radio stations. In the early days, manufacturing companies would pay to
broadcast
complete stories on the radio. These were often plays or
dramas
. Because companies who made soap often paid for them, these were called "
soap operas
".
Microwaves
have even higher
frequency
; shorter
wavelength
. They also are used to transmit television and radio programs, and for other purposes.
Communications satellites
relay microwaves around the world.
A radio receiver does not need to be directly in view of the transmitter to receive programme signals. Low frequency radio waves can bend around hills by
diffraction
, although repeater stations are often used to improve the quality of the signals.
Shortwave radio
frequencies are also reflected from an electrically charged layer of the upper atmosphere, called the
Ionosphere
. The waves can bounce between the ionosphere and the earth to reach receivers that are not in the line of sight because of the curvature of the Earth's surface. They can reach very far, sometimes around the world.
Radio telescopes
receive radio waves from the sky to study
astronomical objects
Satellite navigation
uses radio to determine location, and
radar
uses it to find and track things.
Related pages
change
change source
The
Simple English Wiktionary
has a
definition
for:
radio
Amateur radio
Antenna
Crystal radio
Media studies
Radio wave
Radio astronomy
Wireless
References
change
change source
Wikimedia Commons has media related to
Radio
Know how radio works and how radio waves transfer information from a station to a receiver.
www.britannica.com. Retrieved December 31,2021.
Maxwell’s Equations: Electromagnetic Waves Predicted and Observed
. courses.lumenlearning.com. Retrieved December 31,2021.
Guglielmo Marconi
. www.history.com. Retrieved December 31, 2021.
Other websites
change
change source
Radio
-Citizendium
Retrieved from "
Category
Radio
Hidden category:
Commons category link is on Wikidata
Radio
Add topic