Slides contain the need, the radiation pattern working principle of the antenna array.

1. Antenna
Arrays
Abhishek Pachhain (078BEI001)

2. Antenna Array
Group of antennas connected and
arranged in a regular structure to form a
single antenna.
● Able to produce radiation patterns not
produced by individual antennas.
● Antenna array composed of several
similar radiating elements (e.g., dipoles
or horns).
● Element spacing and the relative
amplitudes and phases of the element
excitation determine the array’s radiative
properties.

3. Need for Antenna Array
More materials and precise
engineering
For long distance
communication, antenna
have to direct the waves to
specific direction.
Wide Beam & Low
Directivity Construction
Complexity

4. Need for Antenna Array
The resonant frequency of a dipole antenna is determined by its
length, typically half the wavelength of the desired frequency.
Larger Antenna may intercept more EM waves but fail to capture
it.
Bandwidth & Resonant Frequency

5. Working Principle:
 At any given point, Electromagnetic Wave is vector
sum of all individual waves produced by each
antenna in array.
 If current are fed to antennas at proper phase, due
to interference of spherical waves, they combine to
from a planer waves. (A beam in specific direction).
 When individual waves arrive in phase, by
constructive interference, the power radiated is
enhanced.
 At points of waves meeting out of phase, the power
radiated is reduced.
For Transmitting Antenna

6. Working Principle:
 The oscillating currents received by
the separate antennas from radio
waves received from desired
directions are in phase and when
combined in the receiver reinforce
each other.
 While currents from radio waves
received from other directions are
out of phase and when combined
in the receiver cancel each other.
At Receiving Antenna:

7. Advantages
Higher Gain
They can focus energy more
effectively in a specific
direction, improving signal
strength and range.
Better Directivity
They provide better control over the
direction of the signal, allowing for
more precise targeting and reduced
interference
Scalability
They can be scaled to meet
different requirements by
adding more elements.
Beamforming
Array antennas can electronically
steer the beam without physically
moving the antenna, providing
greater flexibility and control over
the coverage area.

8. Examples
VHF TV
Antenna Microstrip
Antenna
Very Large
Array Radio
Telescope

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