Broad-band circulator models for active microwave circuit analysis

A general method is presented for determining a broad-band 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 circulator-coupled circuits such as amplifiers and oscillators. The method is applied to two different circulator forms, in coaxial line and waveguide, to show the close agreement to measured performance that can be attained by the method in practice.