UHF - Invented in the 1930's by an Am phenol engineer, E. Clark Quackenbush, for use in the radio industry. UHF coaxial connectors are general purpose units developed for use in low frequency systems from 0.6 to 300 MHz. UHF is an acronym for "Ultra High Frequency". When the UHF was introduced, 300 MHz was considered High Frequency. The coupling on a UHF is threaded. Since UHF connectors are low cost, the impedance is variable.