An RF antenna input is a connector found on the back of television sets. It is sometimes referred to as a coaxial input or cable input.
An RF antenna input is usually used to connect a VCR, DVD player, antenna, cable box or other device to the television set via a coaxial cable. These thick cables usually have screw-in heads to help keep the connection secure, so most RF antenna inputs look like small screws protruding out of the TV.
The technology behind RF antenna inputs is very old, and it is antiquated when compared to other connections such as composite, component and HDMI. It cannot transmit an HD signal, and it is highly susceptible to interference from radio waves and other electronic devices.
Although most HDTVs and other devices still have an RF antenna input, it is rarely used because of its inherent limitations. HDMI and component inputs, both of which support full HD, have taken the place of the older connection. Use of RF antenna today is mostly limited to legacy devices such as VCRs and older video game consoles.