English: Diagram of T antennas (flat-top antennas), a simple type of long wire radio antenna used at low frequency (LF), medium frequency (MF), and shortwave frequencies. The red parts are insulators, the grey are supporting towers. A simple T antenna (a) consists of a horizontal wire suspended between two supports and insulated from them, with a vertical wire attached at the center and hanging down near the ground. The transmitter or receiver is connected between the vertical wire and a ground connection. To increase capacitive top-loading, (b) sometimes several parallel horizontal wires are used, connected together to the vertical wire.