Radio waves are a type of electromagnetic radiation with wavelengths longer than infrared light. They were first theorized by James Clerk Maxwell and confirmed by Heinrich Rudolf Hertz. Radio waves are used for radio broadcasting and cellular networks. Radio broadcasting involves one-way transmission of audio to a wide audience using amplitude modulation (AM) or frequency modulation (FM). Cellular networks transmit radio signals through cell sites to allow mobile communication over a large area. Generations of cellular networks have provided improvements in transmission rates and capabilities.

1. radio waves
Lau Siu Ching Jonathan
p08294715

2. According to an online encyclopedia,
the definition of radio waves are a type of
electromagnetic radiation with wavelengths
in the electromagnetic spectrum longer than
infrared light.

3. James Clerk Maxwell first formally assumed the existence of
electromagnetic waves and it was confirmed by Heinrich
Rudolf Hertz afterwards.

4. Radio waves were broadly used during the
early history of radio to produce radio
instruments. The radio technology
development began as “wireless telegraphy”.

5. Radio broadcasting is a one-way wireless
transmission over radio waves which reaches
a wide range audiences.
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There are two types of modulation used
in the process of radio broadcasting and they
are AM broadcasting and FM broadcasting.

6. AM broadcasting (amplitude modulation)
It is the first method of broadcasting sound on
a radio signal and is still widely used today.
Amplitude modulation was used for a small
scale voice and music broadcasts until the
World War One.

7. FM broadcasting (frequency modulation)
FM radio was invented in the 1930s for
overcoming the interferences problems the AM
radios were facing. And it was made possible
by
spacing station further apart. Frequency
modulation stations are much more popular
since higher sound quality and stereo
broadcasting became the common format.

8. Cellular network
It is a radio network distributed over land areas
called cells, which are transmitted through
fixed-location transceiver known as a cell site
or a base station.

9. Cellular networks are now widely used because
of its advantages, for example it allows a big
range of people using it at the same time, it
reduces power use, and it covers a large area
without huge interference from other signals.
Nowadays, people use them daily with
portable
transceivers (mobile phones/ smart phones).

10. Cellular network was launched in Japan in 1979
as the 1st Generation (1G). But it was replaced
but the 2nd Generation (2G) digital
telecommunication in a year after it was
launched. In May 2001, the 3rd Generation (3G)
was released and the transmission rates are
higher than before and improving.

11. In 2009, the 4th Generation (4G) was
introduced and it is based on cellular wireless
standards. It is now available for a pre-release
trial as a form of LTE (Long-term-evolution) and
it will be available late 2012.