[Note: The Presentation may appear distorted in SlideShare website. It is not. Download it for the best view results. ] This Presentation tries to cover Beam forming, beam steering & beam with changes subtopic for RADAR systems. This PPT was made for Internal Assessment seminar for 18ECOE07- Open Elective I- Introduction to Radar systems- 7th semester, Jain (Deemed-to-be) University, Bengaluru India by Chaitanya Shukla (19BTRAS051)

1. Innovative
Assessment:
Seminar
Seminar topic #33- Beam Steering & Beam width changes
(Unit 5- 18ECOE07)
Chaitanya Shukla (19BTRAS051),
7TH Semester, Aerospace

2. Introduction &
Prerequisite concepts
01
Prerequired concepts to
understand core topic
Beam Steering
02
Brief discussion on core idea
about beam steering
TABLE OF CONTENTS
Beam width Changes
03
Brief discussion on core idea
of Beam Width changes
Conclusion
04
The advantages, disadvantages and
future trends

3. 1.
1
Brief Introduction &
Prerequisite
concepts:
Generation of EM waves through dipole oscillators

4. Dipole
a pair of equal and opposite electric charges or
magnetic poles of opposite sign separated
especially by a small distance
How can it propagate EM waves?
Assume the dipole is oscillating

5. Dipole generating
waveform
The charges will keep interchanging position and this will affect the electric
field around it as show below for different time intervals.
At t=T/4 they will cross each other and the field will separate as shown in next slide.

6. Dipole generating
waveform

7. Practical application: Antenna
What is antenna?
● Antenna is a radiating element which converts our current/voltage
into EM radiation.
● Antenna will propagate that radiation into the space.
● At receiving end, vice versa happens.

8. Practical application-
Antenna

9. 1.
2
Brief Introduction &
Prerequisite
concepts:
Three types of propagation modes

10. Uniform intensity in all
directions like a light bulb.
Isotropic
Propagation in just two
directions.
Biaxial
Directed beam in single
direction often focused on
a single target.
Unidirection / directive
Wave propagation
types

11. Waterdrop Analogy
Comparison
Can be compared to isotropic propagation.
We can see the waves are travelling uniformly in all
direction.
Can be compared to directive propagation.
We can see the waves are travelling uniformly in all
direction.

12. 1.
3
Brief Introduction &
Prerequisite
concepts:
Array based antennas: Need, Classification, Assumptions

13. Problems with conventional isotropic antenna
● Energy is radiated in 3-D sphere. Some part is
received and majority is wasted.
● Range requirements have increased for military
applications.
● Also we want to direct energy in specific direction
without making antenna bulky and continuously
moving bulky antenna.
Conventional isotropic antenna: Problems

14. ● This constructive & destructive
interference is used
mathematically to get precise
narrow beam, uni-directional
beam, beam steering and
changing width of beam. It will
be discussed in further slides.
Solution to problems: Array based antenna
● When single isotropic element (assuming point
source) is arranged in an array of n number of
similar isotropic elements placed equidistance from
each other , have same impendence; it is observed
that the individual waveforms from each element
constructively or destructively interfere with each
other to give a directional focused beam of
Electromagnetic radiation.
Single elemental
antenna in an array-
isotropic
Array
Array
Array
Types
What is an Array?
Linear, Planar, Conformal

15. 1.
4
Brief Introduction &
Prerequisite
concepts:
Beam forming, main lobe & Polar Diagrams

16. What is Beam
Forming?

17. What is Beam
Forming?
Main
Lobe

18. • We have a dipole and
inductor
• We can view them from
above, they look like dots.
• A wave leaving antenna
reaches reflector 1/4th of
wavelength later.
• Due to inductance, wave of
opposite polarity is produced.
• When it reaches antenna, it is
in phase with wave being
created and the pattern can
be seen.
Unidirectional Beam forming has taken place here as one side reenforces constructively
and other as destructively.
Unidirectional Beam
Forming

19. Polar Diagrams
Isometric
elemental radar
Polar & Reflector patter-
Directive / uni-directional
180 out of phase two
dipoles- Bi-directional
Polar Diagram
Increase number of
dipoles to aid this
lobe.

20. Two types of array
based on beam
propagation
Both dipoles 180deg in phase.
Radiation pattern perpendicular to antenna axis
This type is called “Broadside array”
Both dipoles -180deg in phase.
Radiation pattern is along the antenna axis
This type is called “Endfire array”

21. 2.
1
Beam Steering
What is beam steering? Why we need it?

22. What is beam steering?
Beam steering Is changing
direction of main lobe of antenna
radiation pattern
What is need of beam steering?
• We discussed previously that there exists Broadside array & Endfire array that radiate either
perpendicular or parallel to the axis of antenna.
• Beam steering is used if we want to radiate in some other angle between. We cannot always steer
entire bulky antenna and we should have an easy option.

23. 2.
1
Beam Steering
How to achieve it?

24. How is it achieved?
Beam steering is achieved by either means as
follows
Mechanical (conventional)- Servos / Motors
move the array. Not efficient method.
Electrical (Modern)- The current gain is varied

25. How is it achieved?

26. Comparing to waterdrop
analogy

27. 2.
3
Beam Steering
Mathematical Equn. & Notes

28. Mathematical Equation & Notes
Mathematically we need radiation pattern in angle of θ0
We know that, phase angle between 2 antenna elements is:
Where beta is Propagation angle, d is distance between antenna elements inn array, theta is phase angle and
alpha is phase shift.
Changing alpha we can steer antenna pattern
One application is Phased array antenna for receiving or sending EM waves.
When we have steered to required direction theta_0, we say
Hence, equation becomes:
Hence now,
Which proves that antenna angles changed by changing alpha

31. 3.
1
Beam width
Changes
Introduction

33. 3.
2
Beam width
Changes
Half Power Beam Width

36. 3.
3
Beam width
Changes
First Null Beam Width

38. 3.
4
Beam width
Changes
Relation between directivity and Beam Width

40. 3.
5
Beam width
Changes
Notes

41. Notes

42. CREDITS: This presentation template was created by
Slidesgo, including icons by Flaticon, and infographics
& images by Freepik
THANKS!
This PPT will be available to download at
https://slideshare.net/ChaitanyaShukla10
Please keep this slide for attribution
Chaitanya Shukla | LinkedIn
chaitanyashukla999@gmail.com