Explain the HORN used in microwaves?

Explain the HORN used in microwaves

A horn antenna is used for the transmission and reception of microwave signals. A horn antenna serves the same function for electromagnetic waves that a sound horn does for sound waves. It provides a gradual transition structure to match the impedance of a tube to the impedance of free space, enabling the waves from the tube to radiate efficiently into space. For more detail study the link below: http://searchmobilecomputing.techtarget.com/definition/horn-antenna