Switchable microwave circulator wherein ground planes are comprised of foils having vertically conductive particles

Claim 1

In a switchable microwave stripline junction circulator the combination of: a first driving member for conducting magnetic flux; a first ferrite element adjacent said driving member; a first foil comprised of a thin sheet of electrical insulation with a thin film coating of minute separate electrically conductive particles on one side of said thin sheet facing said first ferrite element said separate particles constituting a low-resistance conductive path for microwaves and further constituting a substantial-resistance path to low-frequency currents, said foil being mounted between said driving member and said ferrite element and constituting a microwave ground plane for said circulator; a second ferrite element; first and second dielectric discs each having a central hole for receiving said first and second ferrite elements respectively; a center conductor junction sandwiched between said first disc and said first ferrite element and said second disc and said second ferrite element; a second driving member for conducting magnetic flux, said ferrite elements, dielectric discs and junction being disposed between said first and second driving members; a second foil comprised of a thin sheet of electrical insulation with a thin film coating of minute separate electrically conductive particles on one side thereof facing said second ferrite element said particles constituting a low resistance conductive path for microwaves and further constituting a substantial resistance path to low frequency currents, said second foil being mounted between said second driving member and said second ferrite element and constituting a microwave ground plane for said circulator, said first foil overlying said first ferrite element and said first dielectric disc between said first ferrite element and said first driving member, said second foil overlying said second ferrite element and said second dielectric disc between said second ferrite element and said second driving member; and a source of magnetic flux connected between said first and second driving members for supplying magnetic flux for conduction through said first and second driving members to said first and second ferrite elements, said source being operable to supply magnetic flux to said elements in a first direction, said source being further operable to supply magnetic flux to said elements in a second direction.