Horn Antenna:

#)A horn antenna may be regarded as a flared out or opened out of wave guide.

Wave Guide:

#)A wave guide is capable of radiating radiation into open space provided the same is excited at one end and opened at the other end.

Reason why mouth of Wave Guide is opened:

#)The mouth of the wave guide is opened out which assume the shape of electromagnetic horn, just like a opened out transmission line which gives a dipole.

How Pyramidal Horn is obtained?

#)If flaring is done, along both the walls of the rectangular wave guide, then pyramidal horn is obtained.

How Conical Horn is formed?

#)By flaring the walls of circular wave guide the conical horn is form   

Why the flaring of walls of wave guide is done?

#)To avoid the standing wave ratio, the flaring of walls of wave guide is done which besides matching of impedance, also provide concentrated radiation.

What is the function of electro magnetic horn?

#)The function of electro magnetic horn is to produce a uniform phase front with a larger aperture in comparison to wave guide and thus the directivity is greater.

What is the maximum value of directivity?

The maximum values of directivity are

• 0.25 - Plane horn
• 0.32 - Conical horn
• 0.40 - H-plane horn

What is the maximum phase difference of E-plane horn and H-plane horn?

#)The maximum phase difference of E-plane horn is 72°and the maximum phase difference of H-plane horn is 135°.

What are the uses of horn antenna?

#)Horn antennas are extensively used at microwave frequencies under the condition that power gain needed is moderate.

#)For high power gain, since the horn dimension becomes large, so the other antenna like lens or parabolic reflector etc, are preferred rather than horns.