Advantages of Circulator | disadvantages of Circulator

This page covers advantages and disadvantages of RF Circulator. It mentions RF Circulator advantages or benefits and RF Circulator disadvantages or drawbacks. It provides links on various topics on RF Circulators.

What is Circulator?

Introduction:
A circulator operates based on non-reciprocal property of the ferromagnetic materials. When such materials are placed in DC magnetic field, EM wave propagation becomes non-reciprocal.

It is microwave passive device which allows uni-directional propagation of EM wave similar to isolator. It has many applications. The figure-1 depicts one such application used to share single common antenna between transmitter and receiver.

In this 3-port circulator, signal travels in uni-directional mode i.e. from 1 to 2 and from 2 to 3 etc. The reverse is not possible. It means signal fed at N^th port appears at (N+1)^th but not at (N-1)^th port. As a result, the signal from transmitter at port-1 can be transmitted via antenna connected at port-2. Similarly signal received at port-2 can be fed to receiver connected at port-3. Refer RF Circulator basics and manufacturers>> and RF Circulator Application notes>>.

Following are the types of Circulators.
• Four port circulator and Three port circulator based on number of ports
• Microstrip circulator
• Strip line circulator
• Waveguide circulator

Benefits or advantages of Circulator

Following are the benefits or advantages of Circulator:
➨It has many applications as it is lossless and non-reciprocal device.
➨The 3-port circulator can be used as RF isolator by terminating one of its port.

Drawbacks or disadvantages of Circulator

Following are the disadvantages of Circulator:
➨There is a limit on power handling capability of the RF circulator. This can be increased by lowering impedance or increasing intrinsic line width or increasing substrate thickness.
➨Insertion loss between coupled ports depend on various parameters such as copper loss of strip and ground plane, dielectric loss of input/output strips, magnetic loss of the ferrite disc. All these should be properly managed in order to achieve minimum insertion loss between the coupled ports.

Also refer advantages and disadvantages of Microstrip line, Strip line and Waveguide as RF circulators are designed based on these transmission line types.