RF circulators are used in a variety of RF circuit design applications. Typically they tend to be used at microwave frequencies, hence they are often referred to as microwave circulators.

RF circulators are used as duplexers in many RF applications to allow for simultaneous transmit and receive functions, and they are used in a wide range of RF design applications, including radar systems and a variety of specialized radio communication systems.

One port of the circulator is connected to a load and can be used as an isolator. Therefore, isolators are widely used for the protection of high-power RF sources. To prevent instability or even burnout of the source due to load changes caused by reflected power. Between the antenna and the transmitter or between several communication systems and radar systems, the use of isolators to absorb the reflected power. Thus, it plays the role of protection.