Four-Port Constant R Network Required by a Two-Way Single Amplifier Repeater

Two-way single amplifier repeaters have some definite advantages for long transmission systems. Such repeaters may be built according to various configurations. This paper concerns itself with only one of the possible configurations, namely, the one usually referred to as the four-filter configuration, and which is shown in Fig. 2. First, the necessary and sufficient conditions for the physical realizability of the associated networks are derived. Second, the approximation technique is described that leads to physical networks having a scattering matrix very close to that required. The network realization proceeds following well-known methods. Finally, a particular design is outlined briefly.