Dielectric Filter - Isolator 
- Isolator is an element used in microwave or optical wave transmission circuits. To put it shortly, it is a passive element that fixes the direction of power flow to a single direction. Basic function of the isolator is to remove the galvanic path among input, output and power, which is called a three-way isolator.
The isolator that separates electrical signals of input and output using the buffer device in the midway is an essential element in communication parts. It solves several impacts of small amount of surge, noise, grounding and power.
Therefore, if an isolator is located in the middle of a signal path, power is transmitted to one way but not to the other way. In such a way, the isolator fixes the direction of power flow and rejects signals going to the other way.
As shown in the above figure, the isolator should have three ports in it: an input port, an output port, and an isolation port that bypasses signals coming in from the output port so that they may not return to the input port. The isolator operation is illustrated in the following figure
