Antennas are devices used to radiate and capture the electromagnetic field in space.
1_Broadcast antenna
The role of the transmitting antenna is to transform the electromagnetic power guided from a generator into a radiated power, to ensure propagation in the air. In this sense, it is a transducer.
2_Reception antenna
Conversely, the radiated power can be picked up by a receiving antenna. In this sense, the antenna appears as a sensor and a radiated power transformer in guided electromagnetic power.
3_Reciprocity
An antenna can be used in reception or emission with the same radiating properties, it is said that its operation is reciprocal. But we can always find antennas that contain non-linear materials, they are not reciprocal.
