Even-odd-mode analysis and experimental studies on tap-offs for CATV networks

A new application method was proposed, where the even-odd-mode theory for a symmetrical coupled-line directional coupler was applied to a transformer-type directional coupler. In addition, the tap-offs were analyzed by the proposed theory, which are widely used in CATV (cable television), DBS (direct broadcasting satellite), CS (communication satellite) systems. By comparing the calculation results to the measured ones using the even-odd-mode reflection coefficients only, the validity of the proposed analysis method was confirmed. Then, the tap-off has been broadened from 5 MHz over 4,000 MHz by adopting the proposed theory.