Which device acts as an electrical conductor that radiates or receives radio waves?

The device that acts as an electrical conductor which radiates or receives radio waves is the antenna. Antennas are crucial components in communication systems, as they convert electrical energy into radio waves for transmission and vice versa for reception.

When a transmitter sends out signals, the antenna converts the electrical signals into electromagnetic waves that propagate through the air. Conversely, when a receiver picks up radio waves, the antenna captures these waves and converts them back into electrical signals for processing. This dual functionality is fundamental in enabling wireless communication in various avionics systems, such as navigation, communications, and radar.

Other devices mentioned, like transmitters and receivers, serve different roles in the communication process. Transmitters generate the signals to be sent, while receivers are focused on detecting and interpreting those signals, but neither directly handles the conversion between electromagnetic waves and electrical energy like an antenna does. Modulators, on the other hand, are involved in altering carrier signals to encode information but do not themselves radiate or receive radio waves. This specificity is what distinguishes the antenna as the correct answer in this context.