A fast-switching high power C-band ferrite circulator

A differential phase shift circulator for C band has been developed using non-reciprocal transverse field ferrite elements of novel configuration. In this configuration the non-reciprocal phase shifters are constructed using ferrite toroids with a wire running axially inside the ferrite to magnetize it to remanence. This replaces the usual double ferrite slabs and external magnet. This configuration realizes two advantages. First, the magnetizing coil is inside the waveguide rather than outside and it is not necessary to propagate the switching pulse through the waveguide walls. Second, the ferrite toroids form a closed magnetic path. This allows the ferrite, once magnetized, to remain at remanence without having to maintain the magnetizing current. The circulator uses two differential phase shift sections (jayrators), a magic tee, and a short-slot hybrid coupler. The switching pulse is supplied by a line pulser which would supply current pulses of alternate polarity at the required current (30 amperes). The circulator operated over a frequency range of 4.9 KMc/ sec to 5.6 KMc/sec, with insertion loss of 1.3 db or less, and isolation of 20 db or more, at peak powers up to 550 KW, average power 100 to 200 watts. At higher peak powers sparking occurred, and at higher average powers heating was excessive and the performance seriously deteriorated. The device switched at all peak powers up to 550KW, in 20 nano seconds or less. The device thus offers, a combination of power handling capacity and switching speed not readily attainable by other microwave switches.