- Antennas come in different types based on frequency range, operating range, mode of application, and physical structure. Common types include wire antennas, slot/aperture antennas, reflector/lens antennas, and microstrip antennas. - Key antenna parameters that impact communication systems include radiation pattern, impedance, bandwidth, gain, efficiency, directivity, and polarization. Proper impedance matching between the antenna and transmission line is important for maximum power transfer. A high gain antenna directs radiation more effectively in a desired direction.

1. ANTENNA TYPES AND THEIR
IMPACT ON THE
COMMUNICATION SYSTEMS

2. PREVIEW
• Introduction
• Types of Antenna
• Fundamental Parameters of Antenna and its Impact
on the communication system

4. James Clarke Maxwell (1873)
(Formed the foundation of Classical
Electromagnetism, Classical Optics
and Electric Circuits)
Professor Heinrich Rudolph Hertz (1886)
(Demonstrated the first wireless
electromagnetic System)
Guglielmo Marconi (1901)
(was able to send signals
over large distances)

5. WHAT IS AN ANTENNA?

6. Feeler or horn of an insect or other arthropod
WHAT IS AN ANTENNA?

7. • Antenna is any device that carries an electric
current and thereby produces an electromagnetic
field or responds to an electromagnetic field.
• The spacing, length and shape of antenna
depends on wavelength of tx frequency.
WHAT IS AN ANTENNA?

9. • Important component of wireless comn system.
• Conducting or dielectric in nature.
• Can be used as transmitting or receiving antenna.
• Matching device between wave launching system and Free
space.
INTRODUCTION

11. ANTENNA TYPES
Based on Frequency
Operating Range
Based on Mode
of Application
Based on physical
structure

12. ANTENNA TYPES
Based on Frequency
Operating Range
Based on Mode
of Application
Based on physical
structure

13. ANTENNA TYPES
• Very Low Frequency (VLF) : 3 to 30 KHz / 100 to 10 Km
• Low Frequency (LF) : 30 to 300 KHz / 10 to 1 Km
• Medium Frequency (MF) : 300 to 3000 KHz / 1000 to 100 m
• High Frequency (HF) : 3 to 30 MHz / 100 to 10 m
• Very High Frequency (VHF) : 30 to 300 MHz / 10 to 1 m
• Ultra High Frequency (UHF) : 300 to 3000 MHz / 100cm to 10 cm
• Super High Frequency (SHF) : 3 to 30 GHz / 10cm to 1 cm
• Extremely High Frequency (EHF) : 30 to 300 GHz / 10mm to 1 mm
• Microwave : 300 MHz to 300 GHz
Based on Frequency
Operating Range
Based on Mode
of Application
Based on physical
structure

14. ANTENNA TYPES
Based on Mode
of Application
• Point-to-point communications
• Broadcasting applications
• Radar communications
• Satellite communications
Based on Frequency
Operating Range
Based on physical
structure

15. ANTENNA TYPES
Based on Frequency
Operating Range
Based on Mode
of Application
• Wire Antenna
• Slot and Aperture Antenna
• Reflector and Lenses Antenna
• Microstrip Antenna
• Array / Integrated Circuit Type
Antenna
Based on physical
structure

16.  Radiation Pattern
Impedance matching
Radiation Intensity
Directivity
Aperture Efficiency
Antenna Efficiency
Antenna Gain
Antenna Bandwidth
Beamwidth
Beam Efficiency
Polarisation
FUNDAMENTAL PARAMETERS

17. Diagrammatic representation of the distribution of radiated energy into
space as a function of direction. (2D or 3D)
 Field Patterns – Plotted as a function of Electric Field and Magnetic Field on
a logarithmic scale.
Power Patterns – Plotted as a function of square of the magnitude of Electric
Field and Magnetic Field on a logarithmic scale or commonly on dB scale.
1. RADIATION PATTERN
Antenna Radiation Pattern RP of a Parabolic Reflector

18. 3-D RADIATION PATTERN : DIPOLE
1. RADIATION PATTERN

19. 2. IMPEDANCE MATCHING
• Impedance: Measure of opposition present in a circuit to a current to flow through it, when
voltage is applied.
• When the approximate value of impedance of a transmitter, equals the approximate value
of the impedance of a receiver, or vice versa, it is termed as Impedance matching.”
• Impedance matching is necessary between the antenna and the circuitry. The impedance
of the antenna, the transmission line, and the circuitry should match so that maximum
power transfer takes place between the antenna and the receiver or the transmitter.
Necessity of Matching
• A resonant device is one, which gives better output at certain narrow band of frequencies.
Antennas, as a resonant device, delivers a better output if impedance is matched, .
• The power by an antenna will be effectively radiated, if the antenna impedance matches
the free space impedance.
• For a receiver antenna, antenna’s output impedance should match with the input
impedance of the receiver amplifier circuit.
• For a transmitter antenna, antenna’s input impedance should match with transmitter
amplifier’s output impedance, along with the transmission line impedance.
• VSWR directly proportional to the Impedance mismatch.
Unit. Ohms.

20. VOLTAGE STANDING WAVE RATIO (VSWR)
• The ratio of the maximum voltage to the minimum voltage in a standing
wave is known as ”Voltage Standing Wave Ratio (VSWR)”
• If the impedance of the antenna, the transmission line and the circuitry do
not match with each other, then the power will not be radiated effectively.
Instead, some of the power is reflected back.
The key features are −
• VSWR indicates the impedance mismatch. The higher the impedance
mismatch, the higher will be the value of VSWR.
• The ideal value of VSWR should be 1:1 for effective radiation.
• Also called as SWR.
• Reflected power is the power wasted out of the forward power. Both
reflected power and VSWR indicate the same thing.

21. • Radiation emitted from an Antenna which is more intense in a particular direction.
• Power radiated from an antenna per unit solid angle.
• Obtained by multiplying the power radiated with the square of the radial distance.
i.e. U = r2 x Wrad Watts/Steradian or Watts/radian
3. RADIATION INTENSITY

22. • Direction in which an antenna radiates matters much important.
• Its radiation intensity is focused in a particular direction, while it is
transmitting or receiving. Hence, the antenna is said to have
its directivity in that particular direction.
4. DIRECTIVITY
Maximum radiation intensity of subject antenna
Radiation intensity of an isotropic antenna
Directivity =

23. • Ratio of the effective radiating area to the physical area of the aperture.
• An antenna has an aperture through which the power is radiated. This
radiation should be effective with minimum losses. The physical area of
the aperture should also be taken into consideration, as the effectiveness
of the radiation depends upon the area of the aperture, physically on the
antenna.
Mathematically, the expression for aperture efficiency is as follows −
where
•ε A is Aperture Efficiency.
•Aeff is effective area.
•Ap is physical area.
5. APERTURE EFFICIENCY
A eff
A p
ε A=

24. Antenna Efficiency - Ratio of the radiated power of the antenna to the
input power accepted by the antenna.
Simply, an Antenna is meant to radiate power given at its input, with
minimum losses.
The antenna efficiency explains how much an antenna is able to deliver
its output effectively with minimum losses in the transmission line.
This is otherwise called as Radiation Efficiency Factor of the antenna.
Mathematical expression
Where,
•ηe is the antenna efficiency.
•Prad is the power radiated.
•Pinput is the input power for the antenna.
6. ANTENNA EFFICIENCY
Prad
Pinput
ηe=

25.  Gain of an antenna is the ratio of the radiation intensity in a given direction
to the radiation intensity that would be obtained if the power accepted by
the antenna were radiated isotropically.”
 Gain of an antenna takes the directivity of antenna into account along with its
effective performance. If the power accepted by the antenna was radiated
isotropically, then the radiation intensity we get is taken as a reference.
 Describes how much power is transmitted in the direction of peak radiation
to that of an isotropic source.
 Usually measured in dB.
 Unlike directivity, antenna gain takes the losses that occur also into account
and hence focuses on the efficiency.
Mathematically, Gain, G = ηe x D
Where ηe is the antenna’s efficiency and
D is the directivity of the antenna.
7. ANTENNA GAIN

26.  A band of frequencies in a wavelength, specified for the particular
communication, is known as bandwidth.
 The band of frequencies between the higher and lower frequencies over
which a signal is transmitted.
 The bandwidth once allotted, cannot be used by others.
 The whole spectrum is divided into bandwidths to allot to different
transmitters.
 Also known as Absolute Bandwidth.
 The ratio of absolute bandwidth to the center frequency of that bandwidth
can be termed as percentage bandwidth.
Where
fH is higher frequency,
fL is lower frequency and
fc is center frequency
8. BANDWIDTH
Absolute Bandwidth fH− fL
Percentage bandwidth = =
Center Frequency fc

27. Defined as the ratio of the power radiated within the main beam to the
total power radiated.
Ratio of the beam area of the main beam to the total beam area radiated.
Angular separation between two
identical points on the opposing
side of the major lobe where
radiated power decreases to half
of its max value.
9. BEAMWIDTH
10. BEAM EFFICIENCY
Parameter used to judge the quality of tx
and Rx antenna.
ΩM
B
ΩA
ηB=
Where ηB is the Beam efficiency
ΩMB is the beam area of the main beam and
Ω is the total solid beam angle (beam area)

28. Property of an EM wave describing the time varying direction and relative
magnitude of the electric field. Orientation of E Field component with time.
The type of antenna polarization decides the pattern of the beam and
polarization at the reception or transmission.
11. POLARISATION

29. Horizontal Polarisation : Makes the wave weak, as the reflections from the
earth surface affect it. They are usually weak at low frequencies below
1GHz. Used in the transmission of TV signals to achieve a better signal to
noise ratio.
Vertical Polarisation : Low frequency vertically polarized waves are
advantageous for ground wave transmission. Not affected by the surface
reflections like the horizontally polarized ones. Used for mobile comns.
Linear Polarisation : Antenna helps in maint the wave in a particular
direction avoiding all the other directions, improve the directivity of the
antenna.
11. POLARISATION
Circular Polarisation : When a
wave is circularly polarized, the
electric field vector appears to be
rotated with all its components
losing orientation. Used in
satellite communication such as
GPS.

30. Any Questions ?