A Study on the Adjusting Fine Method of Tap-off for CATV Transmitting Circuits Using Coupled-Line Theory

결합선로이론을 이용한 CATV 전송회로용 Tap off의 미조정방법에 관한 연구

Much time and labor has been conventionally paid for fine adjustment of circuit elements by experience to improve the characteristics of Tap-off for CATV systems. To solve the problem, in this paper, the relations between the even- and odd-mode impedance. Z$_{oe}$ and Z$_{oo}$ of symmetrical 4-port coupled-line directional coupler and power dividing characteristics of Tap-off for CATV system have been derived. After the coupling, the reflectivity and the isolation are represented by Z$_{oe}$ and Z$_{oo}$ only, the fine adjustment of all S-parameters can be performed by controling the elements of Z$_{oe}$ and Z$_{oo}$ only. Furthermore, the validity of the new fine adjustment method proposed here has been confirmed by experiments.