Design and development of high power Ku-band junction circulators

High power Ku-band W.G. junction circulators have been developed for radar applications, in both E and H plane configurations by careful choice of the ferrimagnetic material loading the junction to avoid excitation of higher order spin wave modes and to minimise the absorption loss in the material. From the constraints imposed on the choice of material, it is necessary to characterise the basic junction accurately to achieve the circulator performance over the required radar bandwidth, and results of this work are presented. The performance of the units broadbanded by means of quarter wave impedance steps in the waveguide demonstrates the usefulness of the approach with peak power levels at frequencies in the 16 to 17 GHz band as high as 15OKW in the E-plane configuration and average power up to 300 watts in the H-plane configuration, with bandwidths of 5% andlO% respectively.