The document discusses different types of antennas including aperture antennas. It defines an aperture antenna as an opening or closed surface that is considered an antenna opening. Aperture antennas are surface mountable antennas suitable for fast moving vehicles, aircrafts, and missiles. The different types of aperture antennas discussed are horn and open waveguide antennas, reflector antennas, slot antennas, and microstrip antennas. The document also mentions several analysis methods and principles for aperture antennas including current distribution, aperture analysis, Fourier transform, field equivalence, Hygens, and Babinets principles. It notes that aperture antennas have geometries and designs that can be analyzed.

1. UNIT-II-RADIATION MECHANISMS
AND DESIGN ASPECTS
1

2. Antenna Definition
Antenna is a Metallic device for radiating and receiving
electromagnetic waves(By IEEE).
Accelerated and decelerated of chargers on a
conductor can generate Electro magnetic waves.
All types of conductors which is carrying time varying
current are sources of electromagnetic waves.
Effective radiator can be considered as good antenna.
2

3. Basic Types of Antennas
ANTENNA PARAMETERS
3

4. Detachment of Waves from Conductor
Intuitive Picture of Radiation
4

5. Intuitive Picture of Radiation
5

6. Mathematical steps involved to prove existence of
radiation
6

7. Electric scalar and Magnetic vector potentials
7

8. Classification of Antennas
Wire-Type Antennas Aperture-Type Antennas
Dipoles Horn and open waveguide
Monopoles Reflector antennas
Biconical antennas Slot antennas
Loop antennas Microstrip antennas
Helical antennas
Linearly polarised antennas Circularly polarised antennas
Element antennas Antenna array
Narrow-band Broad-band
Transmitting Receiving
8

9. 9
What is Aperture Antenna?
 Opening or Closed Surface.
That is considering a opening
in a surface as an antenna.
Topics to be covered
Need for Aperture Antenna
Surface mountable antennas
that is suitable for fast moving
Vehicles, Aircrafts & Missiles.
Different Types of Aperture Antennas
Horn and open waveguide
Reflector antennas
Slot antennas
Microstrip antennas
Analysis of Aperture Antennas
Current Distribution Method
Aperture Analysis
Fourier Transform Method.
Principles used to explain aperture
analysis
1. Field Equivalence Principle
2. Hygens principle
3. Babinets Principle
Geometry and Design of Apertures

10. APERTURE ANTENNAS
10