3. What does Wireless
Communications mean?
Wireless communications is a type of data
communication that is performed and delivered
wirelessly. This is a broad term that incorporates all
procedures and forms of connecting and
communicating between two or more devices using a
wireless signal through wireless communication
technologies and devices.
7. Radio and satellite
communication are also
wireless. They operate without
wires between the transmitter
and the receiver. Instead,
communication takes place
through ELECTROMAGNETIC WAVES
9. Electromagnetic waves are waves which can travel through the
vacuum of outer space. Mechanical waves, unlike electromagnetic
waves, require the presence of a material medium in order to
transport their energy from one location to another.
10.
11. - consist of vibrating electric and magnetic
fields that move through space at the speed of
light.They have short wavelength
-An accelerating charged
particle produces an electromagnetic (EM)wave. Elec
tromagnetic waves are electric and magnetic fields
traveling through empty space with the speed of light c.
A charged particle oscillating about an equilibrium
position is an accelerating charged particle.
-
12. -For the propagation and interception of radio
waves, a transmitter and receiver are employed. A
radio wave acts as a carrier of information-bearing
signals; the information may be encoded directly on
the wave by periodically interrupting its
transmission
Receiving antennas intercept part of this radiation,
change it back to the form of electrical signals, and
feed it to a receiver. The most efficient and most
common circuit for radio-frequency selection and
amplification used in radioreceivers is the
superheterodyne.
-
13. The source that produce them and methods of their detection are different, but they have
the following common properties :
Electromagnetic waves are propagated by oscillating electric and
magnetic fields oscillating at right angles to each other.
Electromagnetic waves travel with a constant velocity of 3 x 108 ms-1 in vacuum.
Electromagnetic waves are not deflected by electric or magnetic field.
Electromagnetic waves can show interference or diffraction.
Electromagnetic waves are transverse waves.
Electromagnetic waves may be polarized.
Electromagnetic waves need no medium of
propagation. The energy from the sun is
received by the earth through
electromagnetic waves.
14. Electromagnetic radiation is used for
communications and transmission of information.
The waves that are used in this way are radio
waves, microwaves, infrared radiation and light.
The idea of using a signal lamp to communicate
was used in the 19th century. This method of long
distance communication needed a code. One code
used was Morse code, a series of long and short
flashes of light for different letters of the alphabet.
These signals can only be seen when visibility is
good and for short distances.
