Planar ferrite phase shifter

Claim 1

A planar ferrite phase shifter having an input port and an output port, comprising: an elongated ferrite substrate having opposite parallel planar first and second surfaces and an elongated axis; a first microstrip line, a central microstrip line, and a third microstrip line disposed on said first surface of said ferrite substrate, said microstrips being equally spaced and parallel to said elongated axis; an elongated conductive ground plane disposed on said second surface of said ferrite surface, said central line and said ground plane defining a first pair of transmission lines having input ends and supporting a basically vertical E-field in said substrate, said first and third lines being offset by 90° and -90° at their input ends, respectively, with respect to said central line and defining a second pair of transmission lines supporting a horizontal E-field in said substrate, said two sets of transmission lines having input ends coupled to the input port of the phase shifter and having opposite output ends coupled to the phase shifter's output port, these sets of transmission lines defining quadrature phases creating a circularly polarized wave in said ferrite substrate; and phase shift means coupled to said substrate for magnetizing said substrate along said axis and controlling phase shift between the input and output ports of the phase shifter.