An antenna is a form of transducer that converts sent or received radio frequency (RF) fields into alternating current or vice versa. Antennas are used extensively in LANs, mobile telephony, and satellite communication. Antennas come in all shapes and sizes depending on the frequency the antenna is trying to receive. There are two basic types of antennas: the receiving antenna, which intercepts RF energy and delivers AC to electronic equipment, and the transmitting antenna, which is fed with AC from electronic equipment and generates an RF field.