US Patent 7319435 Balun for an antenna

A balun used in high-power applications capable of accommodating a transmission line includes a core with a top surface and a bottom surface formed from soft iron material. At least two holes are provided through the core between the top surface and the bottom surface to accommodate at least one winding of the transmission line. For a given amount of core material and transmission line wound through the core, the balun serves to maximize the amount impedance on the outside surface of the transmission line to decrease the amount of electrical flux generated where the transmission line is attached to the transmission lines of an antenna.