Microwave transmission devices comprising gyromagnetic material having smoothly varying saturation magnetization

A microwave transmission device comprising,

• first and second ground plane members disposed in spaced parallel relation to each other,
• conductive planar means disposed between and in parallel relation with and spaced from said ground plane members, said conductive planar means having a central portion and a plurality of elongated members extending therefrom for transmitting TEM-mode energy and for suppressing transmission of other modes of energy,
• at least first and second bodies of gyromagnetic material adapted to be magnetized by a magnetic field, said bodies disposed on opposite sides of at least said central portion of said planar means,
• each of said bodies including gyromagnetic material having a saturation magnetization gradient providing frequency characteristics for broad bandwidth operation of said device where said gyromagnetic material includes a ferrite material exhibiting a smoothly varying saturation magnetization as a function of position in a plane parallel to said first plane.

A 3-port circulator device operative over a broad pass band of frequencies for non-reciprocally transferring microwave energy in TEM mode among three ports, each of said ports having an outer conductor and a coaxial inner conductor, said device comprising,

• first and second conductive ground plane members disposed in spaced parallel relation to each other and spaced apart in one region by a ground plane spacing S for inhibiting higher-order TE mode transmission within said pass band, each of said conductive ground plane members connected to the outer conductor of each of said ports,
• a center conductor disposed in a center plane between and in parallel relation with and equally spaced from said ground plane members, said center conductor having a central portion and three legs extending along radial axes at equal radial angles from said central portion, each one of said legs connected to a different coaxial inner conductor for a different one of said ports for TEM mode transmission within said pass band,
• first and second composite bodies, said first composite body disposed between said first ground plane member and said center conductor, said second composite body disposed between said second ground plane member and said center conductor, each of said composite bodies including,
• a ferrite cylinder having a smoothly varying saturation magnetization where saturation magnetization near the outer diameter is less than the saturation magnetization near the center of the cylinder, said ferrite cylinder disposed concentrically within a dielectric cylinder, said ferrite cylinder having an outer diameter equal to one-half the wavelength of electromagnetic energy transmitted at a low ferrite frequency within the pass band of said device, said composite bodies functioning to inhibit higher-order TM mode transmission within said pass band,
• magnetic field means for establishing a magnetic field in a direction normal to said center plane to bias said ferrite cylinders below saturation.