Types of Antenna

On the basis of their Structure and applications Antennas can be divided into five major parts. They are following...

1. Wire Antennas
2. Microstrip Antennas
3. Reflector Antennas
4. Travelling Wave Antennas
5. Aperture Antennas

Now Wire Antennas are also of  five different types. They are...

1. Short dipole
2. Dipole
3. Monopole  
4. Small loop
5. Half wave dipole

1) Short Dipole: It is the simplest of all antennas. It can be made of a simple wire, with a center-fed driven element. They are used as antennas, notably in traditional "rabbit ears" television antennas. Word "short" or "small" in antenna always imply "relative to a wavelength".

2) Dipole Antenna: The dipole antenna is similar to the short dipole except it is not required to be small compared to the wavelength at which antenna is operating. 

   Dipole Antenna

3) Monopole Antenna:  A monopole antenna is one half of a dipole antenna, always mounted above some ground plane. 

Monopole Antenna

One side of antenna feed line is attached to the lower end of the monopole, and the other side is attached to the ground plane, generally to the ground.

4) Loop Antenna: A small loop antenna is a loop of wire or tubing with its end connected to a transmission line. Due to radiation resistance and high reactance they are often used as receiver antennas. They have poor efficiency. 

Loop Antenna

5) Half Wave dipole: Half wave dipole is a special type of dipole antenna but is enough important to have a different type. The half wave term means that the length of this dipole antenna is half wavelength of operating frequency. 

Continued...