antenna array

1. Antenna Array and Its Types
• Presentation for Interview
• [Your Name] | [Date]

2. Introduction to Antenna Arrays
• - Definition: An antenna array is a set of
multiple connected antennas that work
together to transmit or receive
electromagnetic waves.
• - Purpose: Enhances gain, directivity, and
beam steering.
• - Applications: Radar systems, wireless
communications, satellite systems.

3. Need for Antenna Arrays
• - Increased Directivity: Helps focus energy in a
specific direction.
• - Beam Steering: Direction of the main lobe
can be controlled electronically.
• - Improved Signal-to-Noise Ratio (SNR)
• - Array Gain: Multiple antennas increase
power reception.

4. Basic Concepts
• - Element: Single antenna in an array.
• - Spacing: Distance between elements (usually
λ/2).
• - Array Factor: Mathematical function
representing the array's radiation pattern.

5. Types of Antenna Arrays
• 1. Linear Array
• 2. Planar Array
• 3. Circular Array
• 4. Phased Array
• 5. Broadside and Endfire Arrays

6. Linear Array
• - Description: Elements arranged in a straight
line.
• - Advantages: Simple design, good
beamforming.
• - Applications: Radio and radar systems.
• - Types:
• - Uniform Linear Array (ULA)
• - Non-uniform Linear Array

7. Planar Array
• - Description: Elements arranged in a two-
dimensional plane.
• - Benefits: 2D beam steering and higher gain.
• - Applications: Satellite and airborne radar.

8. Circular Array
• - Description: Elements placed on the
circumference of a circle.
• - Features: 360-degree coverage.
• - Use Case: Direction finding, surveillance.

9. Phased Array
• - Description: Beam direction is changed by
adjusting the phase of individual elements.
• - Key Feature: Electronic beam steering.
• - Application: Military radar, 5G systems.

10. Broadside vs Endfire Arrays
• - Broadside: Maximum radiation is
perpendicular to the axis.
• - Endfire: Maximum radiation is along the axis.
• - Comparison:
• - Broadside: βd = 0
• - Endfire: βd = ±kd

11. Derivation of Array Factor
• For an N-element Uniform Linear Array:
• AF(θ) = Σ_{n=0}^{N-1} e^{j(nkdcosθ + φ)}
• Where:
• k = 2π/λ (wave number)
• d = element spacing
• φ = phase difference between elements

12. Simplified Array Factor Expression
• Assume uniform amplitude and spacing:
• AF(θ) = sin(Nψ/2) / sin(ψ/2), where ψ =
kdcosθ + φ
• Used to compute the radiation pattern of the
array.

13. Practical Considerations
• - Mutual Coupling: Interaction between
elements.
• - Element Spacing: Avoid grating lobes (d < λ).
• - Feed Network: Needs precise phase and
amplitude control.

14. Applications Recap
• - Wireless communication (MIMO)
• - Radar and sonar systems
• - Satellite communication
• - Direction finding

15. Conclusion
• - Antenna arrays offer flexibility, increased
gain, and directional control.
• - Understanding types and principles is
essential for modern communication systems.

16. Q&A
• Thank you!
• Open for questions.