An antenna (or aerial) was a transducer designed to transmit or receive electromagnetic waves.
Communication for the Ares mission was run jointly by NASA and the ISA, so the Ares IV transmitted to and received information from NASA Mission Control in Houston, Texas. The module used a high-gain antenna and, as such, there was a delay of several minutes for messages sent from Ares IV to Earth and vice-versa. Communication between Ares IV and the surface of Mars, however, was almost instantaneous. (VOY: "One Small Step")
On the Shore Leave Planet, a series of antennae was used to track the movements of visitors to the planet. When most of the crew from the USS Enterprise took shore leave there in 2267, the antennae firstly followed Captain Kirk and Doctor McCoy, then Kirk alone, and later McCoy and Yeoman Tonia Barrows. (TOS: "Shore Leave")