Give the basic function of the antenna.

Hint: An antenna is a basic part of an analogue communication system that is essential in receiving as well as transmitting signals. Most commonly antennas are involved in the transmission and reception of radio wave signals.

Complete step by step answer:
An antenna is a basic device that is made up of a series of conductors. It is a device that becomes a part of both the transmission and reception system of a communication system.
An antenna receives electromagnetic radiation and converts it into radio frequency electrical signals on the receiver’s end. During transmission, the analogue radio frequency electric signals are converted by the antenna into electromagnetic radiation and spread in all directions in the surrounding medium (air, space or water).

Additional information:
The length of an antenna should be typically within a quarter of the wavelength of the radiation which it receives and transmits. This is because in this configuration, there is minimum loss in power while transmitting and receiving the signals.
Due to this antennas are most suited for receiving and transmitting radio waves, since it is physically possible to construct an antenna with length within a quarter of the wavelength of a typical radio wave $\left( \approx 100m \right)$.

Note: Antennas are found in many sizes ranging from $1mm$ to $100m$. Antennae are found upon cars commonly due to which they can receive radio signals and the radio system in the car can play radio music. Sometimes antennas also include other elements like parabolic reflectors that can better concentrate all the radiation energy received and provide better efficiency of transmission and reception of the signals.