X-band high-peak-power junction circulator: Influence of the static magnetic field

The influence of the steady magnetic field on the peak-power handling capability of a junction circulator is studied. A similarity between the variation of the critical power Pc(measured on the circulator) and the critical field hc(measured in cavity) versus static magnetic field is observed. It is particularly attractive to apply a magnetic field whose value is near the limit magnetic field Hlimfor which nonlinear effects disappear. In this case the critical power is very high. In order to prevent the decrease of the magnetic field (delivered by the magnet) with increasing temperature, it is desirable to use samarium-cobalt magnets so that the magnetic field is near the limit field Hlim. When the magnet is temperature unstable (for instance, barium ferrite) it is possible to achieve high peak-power performance at temperatures above room temperature with relaxing-ion-doped garnets but at the expense of higher insertion loss.