Broad-band circulator models for active microwave circuit analysis

A general method is described for determining a broadband equivalent circuit of a lossy, nonideal circulator from the scattering parameters over the frequency range of interest. The equivalent circuit has application to the design and analysis of such circulator-coupled circuits as amplifiers and oscillators. The method is applied to two different circulator forms, in coaxial line and waveguide, to demonstrate the close agreement to measured performance that can be attained by the method in practice.