An antenna is a vital component of any communication system which is used at both transmitting and as well as receiving end.
An antenna is basically a conversion device and is made up of a long conductor.
At the transmitting end, it converts electrical energy into the electromagnetic wave and then radiates into free space, at the receiving end it receives electromagnetic waves and then transforms them into electrical signals which act as input for the receiver.
Antennas are basically of two types dipole and dish antenna.
A dipole antenna is omnidirectional and is used in the transmission of radio waves whereas dish antenna is a directional antenna used typically in radars and satellite communication.
There are many other types used in, for example, your phones, wifi routers, leap cards, contactless credit cards etc