Horn Antenna - Working, Advantages and Applications

Horn Antenna - Working, Advantages and Applications

The dipole is a opened out transmission line which has the total length of 1/4 and which fully couples the electric field into the space. In a similar manner the wave guide also has the capability to radiate the energy into the space when it is suitably excited at one end and opened out at the other end. This type of arrangement is known as t torn Antenna. Thus we can say that the horn antenna is an opened out wave guide which couples the electric field fully into the space. It is used to opened out wave guide to transmit or receive microwave frequency signals.

The horn has the shapes as shown in below Figure with proper impedance matching all the energy fed at the input end of the wave guide will be radiated fully and hence causes more improvement in directivity. The disadvantage is that the diffraction is reduced.

Types of Horn Antennas

1. Sectoral horn flared in 'H' plane.

2. Sectoral horn flared in 'E' plane.

3. Pyramidal horn

4. Circular or conical horn

5. Bi-conical horn

Horn Antenna and its types

H plane horn (sectoral horn) is the horn which is flared out in horizontal direction. The E plane horn is also a sectoral horn which is flared out in vertical direction only. The pyramidal horn is the horn which is flared out in both the directions. The circular horn is similar to a H plane or a E plane horn but it is now flared out from a circular wave guide. So the horn antenna can be effectively feed from a wave guide.

Radiation from Horn Antenna (Working)

When a wave guide is suitably excited at one end and opened at the other end a small portion of the energy will be radiated. The reason is mismatch at the end of the wave guide with space. If the mouth of the waveguide is opened out, the draw back of mismatch can be avoided. This opening of the wave guide results in an electro-magnetic horn.

When the wave guide is terminated by a horn, the abrupt discontinuity is replaced by a gradual transformation and impedance matching is correct. Hence all the energy travels forward and will be radiated. The shape of a radiated field depends on the flare angle of the horn.

The pyramidal horn and the conical horn give pencil like beams that have pronounced directivity in both vertical and horizontal planes. Fan shaped beams result for sectoral horns. The biconical horn produces a pomcake shaped beam in vertical direction but uniform in horizontal plane.

Advantages of Horn Antenna

 1. Good directivity

2. Adequate band width

3. Simple mechanical construction

4. Convenience to employ with wave guides

Applications of Horn Antenna 

1. As primary radiator for paraboloid reflectors

2. For satellite tracking purposes

3. At communication stations