Numerical studies about the temperature compensation of microwave circulators

Microwave circulators and isolators are widely used components in various RF devices. During operation the environment temperature can change over broad ranges. Temperature variations cause the magnetic properties of the ferrite material used within the circulator to change and the biasing static magnetic field needs to be adjusted in order to maintain proper operation. Special nickel-iron alloys within the magnetic circuitry can be utilized for this purpose. A numerical approach for the analysis of the RF performance at discrete temperatures is described. General design guidelines, practical aspects and limitations of the temperature compensation are derived from a simple configuration. The method is applicable for various commonly used circulator designs.