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- Isolators / Circulators
An isolator is a product which a termination resistor is connected to any one of the terminals of the three terminals of a circulator, as shown in Fig. In this Fig., the termination resistor is connected to terminal ③. High-frequency signal that has entered from the terminal ① is transmitted to the terminal ② with minimal loss, as in the case of circulator.
But the high-frequency signal that has entered from the terminal ② is absorbed by the termination resistor connected to the terminal ③, and is almost not transmitted to ①. Ideally, the reflection from the termination resistor is ""0"", but normally there is some mismatch and the power due to the mismatch is input to the terminal ③, and is transmitted to terminal ① similarly as in the circulator.
As in the Fig., the power absorbed by the termination resistor is converted into heat and is eventually discharged to the outside (air).Usually, since the isolator is a two-terminal component, so when you look from outside it appears that the power that has entered the terminal ② is consumed in the isolator and only a small part of it is transmitted to the terminal ①.