Active vertical monopole antennas have become very popular in the EMC community within the last decades. They are mentioned in several EMC standards, e.g MIL STD 461, ANSI C63.5, IEEE 291, CISPR 16-1-4 and CISPR 25 and many others. Most available designs have a vertical rod of typically 1 m length, some models come with 41 inch rods (1.04 m), others have telescopic elements to set up a variable length. Many models are equipped with a metallic counterpoise of 0.6 x 0.6 m. Nearly all available vertical monopole antennas are battery driven to avoid difficulties with multiple reference ground conditions