Radio communication uses radio waves to transmit signals through modulation of a carrier wave. The two pioneers of radio communication are Guglielmo Marconi, who first transmitted a radio signal across the Atlantic, and Nikola Tesla, who first developed a way to transmit radio signals. Radio waves carry signals for technologies like radio, television, and cellular phones and different frequency bands are used to avoid signal interference. Modulation methods include amplitude modulation, which varies the amplitude of the carrier wave, and frequency modulation, which varies the frequency.

1. by-Amin, Mohammed Istiaque

2. Radio communication are done by using radio waves
These waves can travel through space with a
constant speed that is the speed of light. In this
process a signal is modulated with a carrier wave
which is then transmitter later it is received by a
receiver and demodulated to get back the original
signal.

3. The use of radio communications has been
extremely relevant in the western world for well
over a hundred years now. There is still a lot of
confusion and uncertainty to who is behind the
creation of radio communication but the two men
who are seen to be the fathers of radio
communication are Tesla and Marconi.
 Guglielmo Marconi was the first person to create a
radio signal that crossed the Atlantic. This was seen
as a measure that made radio waves a significant
way of communication.
 Nikola Tesla was the first person to develop a way
of transmitting radio signals.

4. Radio waves are a type of electromagnetic waves
having the longest wavelengths in the
electromagnetic spectrum. Sometimes they are
longer than a football field or as short as a football.
They travel in the space with the speed of light.
Radio waves do more than just bring music to your
radio. They also carry signals for your television and
cellular phones. These signal gets weaker as they
travel by reflection and refraction in ionosphere or
by different objects like ground houses etc

5. Different media types use different frequencies so
that the signals are not overlapped and interrupted.
AM Radio Frequencies - 180 kHz to 1.6 MHz.
FM Radio Frequencies - 88kHz to 108 MHz.
TV signals - 470 to 854 MHz.
Mobile Phone signals - 872-960 MHz,1710-1875 MHz
and 1920 - 2170 MHz.

7. Frequency Modulation
Amplitude Modulation

8. In this type of modulation the amplitude of the
carrier wave is modulated or changed with respect
to the signal that is intended to be transferred
where as the frequency is kept constant

9. In this type of modulation the frequency of the
carrier wave is modulated or changed with respect
to the signal that is intended to be transferred
where as the amplitude is kept constant

10. Transmitter- This part of the Radio transmits
the radio wave via Antenna
Block diagram of a basic radio transmitter

11. Receiver – this part of the radio system
receives the modulated signal sent by the
transmitter and then demodulates it to get back the
original signal and then sent to the output device
Block diagram of a basic radio transmitter

13. Audio radio- Mainly AM or FM method is used in Audio
radios. Where the amplitude or the frequency of the
carrier is made proportional to the sound captured
and then transmitted. Transmissions are effected by
static and interference lightning and other radio
emitting sources.
Television-In a television picture is sent as AM and
sound is sent by either AM or FM with the sound
carrier having a fixed frequency away from the video
carrier.

14. Navigation- Satellites emits signals to receivers that
determine their location by computing the
difference between the time that a signal is sent and
the time it is received. GPS satellites carry atomic
clocks that gives accurate time. The time is placed
in the broadcast by the satellite so the receiver can
determine the time the signal was broadcast. The
signal contains data that a receiver uses to compute
the location
Radar- It detects objects at a distance by bouncing
radio waves off them. The delay caused by the echo
measures the distance. The direction of the beam
determines the direction of the reflection. The
polarization and frequency of the return can sense
the type of surface.

15. A team of engineers in Stanford University recently
invented a wireless pressure sensor which is used to
monitor brain pressure by the help of radio waves in
lab mice and it is possible use with human patients.
Freevolt, a new technology that harvests electricity
from unused radio waves, it turns ambient radio
frequency waves into usable electricity to charge
low-power electronic devices, such as sensors and
small wearable electronics

16. The Application of radio communication developed
very rapidly. It is widely used almost everywhere
everyday by almost everyone.

17. National Astronauts and Space Administration. [Web Definition]
[Accessed 22/01/11] Available form:
http://science.hq.nasa.gov/kids/imagers/ems/radio.html
National Astronauts and Space Administration(2010). [Online
Image] [Accessed 22/01/11] Available form:
http://science.hq.nasa.gov/kids/imagers/ems/radio.html
http://engineering.stanford.edu/news/stanford-team-invents-
sensor-uses-radio-waves-detect-subtle-changes-pressure
http://www.faa.gov/about/office_org/headquarters_offices/ato
/service_units/techops/navservices/gnss/gps/howitworks/
http://www.telegraph.co.uk/technology/news/11901430/How-
energy-harvested-from-disused-radio-waves-could-power-the-
smart-home-of-the-future.html