The CATV(cable television) systems have a very important role in mass communications even in DBS(direct broadcasting satellite) systems. The power splitter and the tap-off which are dealing with the video signal in CATV and DBS System have a very significant parts as singal transmission equipments. Especially, the power splitter and the tap-off with high performance and broadband characteristic requirer high quality signal transmission.
Due to the extensive increase of CATV and DBS systems applications in recent years, the frequency band has been extended from 5MHz to 1350 MHz or 1750 MHz. The extension of frequency band from 5 MHz to 2,450 MHz will be required in the near future, the main object of this thesis is to analyze and design optimally the power splitter as transmitting circuits for the CATV and DBS systems.
In this thesis, a new analysis and design method of the tap-off as the CATV transmission networks were proposed, by adopting the even-odd mode theory and by adding compensation circuits.
The transformer type power splitter is theoretically proven by even-/odd-mode analysis using Wilkinson power divider theory, and the proposed design method by adding compensation at the input port for reducing return losses at the input port. Therefore, the measured results of frequency characteristics for the fabricated circuits logically agree well with the theoretical ones, and hence, the validity of the proposed analysis and deign method are confirmed. As a result, the transformer type at the power splitter for the input port compensation showed better performance than conventional ones in the frequency band from 5 MHz to 1,000 MHz.