this is the presentation about different waves and antennas present in telecom technologies.

2. SIGNAL
--FREQUENCY & WAVE LENGTH

3. ELECTROMAGNETIC WAVE
 Electric field –
voltage changes
occurring in the RF
antenna which is
radiating the signal
 Magnetic field–
changes in the current
flow

4. WHAT IS ANTENNA ?
 Photons -- Electrons Electrons -- Photons

5. RADIATION MECHANISM

6. ELECTROMAGNETIC WAVE

7. SIMPLE DIPOLE ANTENNA

8. RESONANCE

9. POLARIZATION
 EM waves are composed of
two planes – vertical and
horizantal (E and M fields)
 If the s/g is Txed in one
polarization , must be Rxed
in same polarization
 Otherwise attenuation
 When the wave is in
 V-plane – V-polarization
 H-plane– H-polarization

10. TYPES OF POLARIZATION

11. ELECTROMAGNETIC SPECTRUM

12. WAVES USED IN TELECOMMUNICATION
 Radio waves
 Radiated by the
Omnidirectional antennas
 Transmits UHF frequencies
 Micro waves
 Radiated by the directional
antennas
 Transmits 0.3GHz-300GHz

13. ANTENNAS FOR RADIO WAVES

14.  Omni directional antennas for horizantal plane
 Also called sector antennas
 For multipoint side of point to multipoint applications
 Beam width 45-180 degrees
ANTENNAS FOR RADIO WAVES

15. RADIATION PATTERN OF RF ANTENNA

16. ANTENNAS FOR MICRO WAVES

17. ANTENNAS FOR
MICRO WAVES
 Low power mw sources –
FET, Tunnel , Impatt, Gunn
diodes
 High power mw sources –
magnetron , klystron, TWT,
gyrotron
 Used for point to point
communications
 Shorter wavelengths and
high frequencies
 Antenna size is inversily
proportional to the
transmitted frequency
 Allowing frequency reuse

18. PATCH ANTENNA USED IN MOBILES

19. CONSTRUCTION OF PATCH ANTENNA
 Simple patch antenna uses
one half wave length
 two metallic plates
separated by a dielectric
layer.
 Metalic plates made of
copper
 Antenna is fed by 50ohm
transmission line
 Generation of E and H fields
dependent on length and
width of the patch and
wavelength

20. E AND H FIELDS OF A PATCH
 E-field
 varies along the length of
the patch
 minimum at the centre and
maximum at the edges
 The H-field
 varies along the length is in
a direction perpendicular to
the E-field.
 maximum at the center and
minimum at the edges.
 The impedance is zero at
the center of the patch

21. PATCH ANTENNA RADIATION PATTERN

22. PATCH ARRAY ANTENNA RADIATION PATTERN

23. RADIATION PATTERN FROM A CELL PHONE

24. RADIATION FROM MOBILE PHONE