should be separated by at least one full wavelength of the lowest frequency to be received at their closest point. Often when multiple antennas are used, one is for a range of co-located stations and the other is for a single transmitter in a different direction. Safety TV antennas are good conductors of electricity and attract lightning, acting as a lightning rod. The use of a lightning arrestor is usual to protect against this. A large grounding rod connected to both the antenna and the mast or pole is required. Properly installed masts, especially tall ones, are guyed with galvanized cable; no insulators are needed. They are designed to withstand worst-case weather conditions in the area and positioned so that they do not interfere with power lines if they fall. There is an inherent danger in being on the rooftop of a house, required for installing or adjusting a television antenna. See also Radio masts and towers, sometimes called Radio and TV antennas Satellite dish Satellite television Terrestrial television References External links Article on the basic theory of TV aerials and their use See Which TV Stations You Can Get on a Map 'Up on the roof' antenna page Antennas (radio) Radio electronics Radio frequency antenna types Radio frequency propagation Radio technology Antenna