Q.Where do you use a circulator?

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A. As shown in Fig. (a), it is used in the antenna duplexer, and in combination with steep BPF it is used in branching circuits (Fig.(b)). Further, if the termination resistor built into the isolator does not meet the required standards for the reflected power, instead of using built-in termination resistor, the resistor is connected external to the circulator to use it as an isolator as shown in Fig. (c). By using the attenuator (ATT) instead of the termination resistor, it becomes a circulator with reflected power detection functionality (Fig.(d)).

Fig. (a) Used for antenna duplexer

Fig. (b) Used in branching circuit

Fig. (c) Used as an isolator, by connecting a termination resistance externally

Fig. (d) Used as a circulator with reflected power detection functionality, by connecting an attenuator (ATT) externally