Guyed masts are frequently used for radio antennas . The mast can either support aerials (for VHF and UHF ) mounted at its top, or the entire structure itself can function as an antenna (for VLF , LF , MF ); this is called a mast radiator . In the latter case, the mast needs to be insulated from the ground . Guyed radio masts are typically tall enough that they require several sets of guy lines, 2 to 4, attached at different heights on the mast, to prevent them from buckling. An exception was the Blaw-Knox tower , widely used during the 1930s, whose distinctive wide diamond ( rhomboidal ) shape gave it the shear strength that it only required one set of guys.