Isolator/circulator is a kind of device which adopts non-reciprocal characteristics of ferrite materials to achieve non-reciprocal transfer of microwave signals. In a circulator, microwave signal imports from one port and exports to the adjacent port repeatedly in order to realize signal transmission. When a port of circulator is connected with matching load, the circulator can be used as an isolator, also known as single-direction transfer, which only allows microwave signal to pass in single direction. Isolator/circulator involves forms, such as stripline, microstrip, waveguide, etc., widely used in many fields like radar, microwave communications (including satellite communications and mobile communications) and microwave energy.