A rectena is a rectifying antenna, a special type of antenna that is used to convert electromagnetic energy into direct current (DC) electricity. They are used in wireless energy transmission systems that transmit energy by radio waves. A simple rectangle element consists of a dipole antenna with an RF diode connected through the dipole elements. The diode rectifies the AC current induced in the antenna by microwaves, to produce DC power, which feeds a load connected through the diode. Schottky diodes are generally used because they have the lowest voltage drop and the highest speed and therefore have the lowest power losses due to conduction and switching. Large rectenas consist of a set of many such dipole elements.