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")