• All satellites need to have some means of communication with Earth; the satellite may need to receive instructions and transmit the information it collects, or it may relay information sent to it to another site on Earth
• This is generally done using some type of antenna
• Antennas are defined simply as a piece of equipment that allows transmission and reception of radio signals
• Since the information is transmitted using radio waves, which move at the speed of light, this method allows for very fast communications (only a very small time lag)
• Antennas come in many families: simple, dishes, patch arrays, and inflatable.