ABSTRACT
Antenna: An antenna is used to radiate efficiently electromagnetic energy in desired directions. Antennas match radio frequency systems to space. All antennas may be used to receive or radiate energy. Antennas transmit or receive electromagnetic waves. Antennas convert electromagnetic radiation into electric current, or vice versa. Antennas transmit and receive electromagnetic radiation at radio frequencies. Antennas are a necessary part of all communication links and radio equipment. Antennas are used in systems such as radio and television broadcasting, point-to-point radio communication, wireless local area network (LAN), cell phones, radar, medical systems, and spacecraft communication. Antennas are most commonly employed in air or outer space, but can also be operated under water, on and inside the human body, or even through soil and rock at low frequencies for short distances.
