Broadband circulator wherein differential phase shift varies with frequency in predetermined manner

Claim 1

In a circulator of the type including: a first transmission path including a reciprocal phase shifter and a first differential phase shifter, a second transmission path including a second differential phase shifter, hybrid means coupled to each end of the two transmission paths for providing at each end power splitting of signals applied thereto, said first differential phase shifter responsive to signals applied thereto for providing additional phase shift to signals propagating in a first direction along said first transmission path and said second differential phase shifter responsive to signals applied thereto for providing additional phase shift to signals propagating in a second direction opposite said first direction, said reciprocal phase shifter inherently providing in response to signals over a wide range of frequencies changes in the amount of phase shift, the improvEment comprising: said first differential phase shifter being arranged to provide a differential phase shift that decreases a given amount with increase in frequency, and said second differential phase shifter being arranged to provide a differential phase shift that increases a given amount with increase in frequency, and said given amount of said increase and decrease being determined relative to said changes in the amount of phase shift provided by said reciprocal phase shifter to provide no difference in the relative phase shift of signals propagating in one direction along said paths and to provide 180* difference in the relative phase shift of signals propagating in the opposite direction along said transmission paths.