Frequency-range widening of three-transformer CATV divider using a bead-type ferrite core

This paper describes the frequency-range widening of a three-transformer CA TV divider consisting of one divider transformer and two matching transform ers, all of which use a bead-type ferrite core. For frequency-range widenin g, the shape and material of the ferrite core, transformer windings, and tr ansformer packaging are theoretically studied by means of a newly proposed high-frequency transformer equivalent circuit. For the divider designed bas ed on the theoretical study, excellent measurement results are obtained in the frequency range of 20 to 3000 MHz, including a divider loss of 3.6 to 4 .6 dB and more than 20 dB of coupling loss between terminals. In the design emphasizing a flat frequency characteristic at some expense of divider los s from a low to intermediate frequency range, the flatness is found to incr ease to about +/-0.3 dB. (C) 2001 Scripta Technica.