Perturbation Techniques for Miniaturized Coaxial Y-Junction Circulators

摘要

Using theoretical synthesis procedures as a guide, systematic means were developed for constructing miniaturized coaxial Y-junction circulators at frequencies in C and X band. Subsequent investigation revealed that these techniques are useful at all frequencies down to the uhf region. Maximum realization of theoretical possibilities calls for techniques of symmetrically altering the junction that yield broad-range adjustment of the junction scattering matrix eigenvalues. Such techniques, involving dielectric loading and systematic deformation of the junction, are described. The device to be described, including permanent magnets, measures 1.5 in. in diameter, 0.75 in. in height, and weighs less than 4 oz. Using the techniques to be presented, the device can easily be made to operate as a circulator at all frequencies from approximately 4 kMc to 10 kMc. Adjusted for use over the 5.4–5.9 kMc range, the circulator exhibits isolation greater than 20 db, insertion loss less than 0.5 db, and VSWR less than 1.3. These characteristics are maintained over a temperature range from -55°C to 110°C. At 5.65 kMc the circulator was operated satisfactorily at peak powers above 25 kw and average powers in excess of 25 w. No special cooling techniques were employed.