This AIR discusses the use and application of EMC antennas and antenna factors. The relationships between antenna gain, antenna factor, power density (W/m2), and field strength (V/m) are discussed. Some examples of their use are given. Illustrations of commercially available EMC antennas commonly used in performing EMI measurements are included. In addition to the illustrations, the antenna factors, frequency ranges, typical uses (applications), and the manufacturers of these antennas are also listed.