SWITCHABLE MICROWAVE CIRCULATOR WHEREIN GROUND PLANES ARE COMPRISED OF FOILS HAVING VERTICALLY CONDUCTIVE PARTICLES

• US 3,614,670 A
• Filed: 11/05/1969
• Issued: 10/19/1971
• Est. Priority Date: 11/05/1969
• Status: Expired due to Term

• Current Assignee: Richard G Wilson
• Original Assignee: Richard G Wilson
• Inventors: Wilson, Richard G.
• Primary Examiner(s): Saalbach, Herman Karl
• Assistant Examiner(s): Gensler, Paul L.
• Application Number:
  US04/874,191
• Time in Patent Office: 713 Days
• Field of Search: 333/1.1,24.1,7,97S
• US Class Current: 333/1.1
• CPC Class Codes: H01P 1/387 Strip line circulators

Abstract

A switchable microwave circulator having ground planes comprised of thin sheets of electrical insulation that have a coating of minute separate aluminum particles on one side that provides a continuous conductive path to microwaves and a resistive path to low frequency currents. The resistance of the coating eliminates induced currents that would otherwise flow around the driving members and pole pieces of the circulator during fast switching of the circulator and would slow the switching of the circulator.

Claims

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.

2. The combination of claim 1 wherein said foil is a sheet of polyethylene terephthalate resin having a particulate coating of aluminum on one side, said sheet being on the order of 0.001 inches thick, said coating presenting substantially zero resistance to microwaves, said coating presenting a resistance of approximately 5 ohms per unit square to direct current.

3. The combination of claim 1 further including a housing having first and second flat parallel members for mounting said circulator, said members having opposing flat parallel surfaces, said members each having a groove formed in said opposing surfaces for receiving said first and second driving members respectively, said first and second foils being entirely flat and positioned against the parallel surfaces of respective first and second housing members and overlying said first and second driving members respectively.

4. The combination of claim 1, further including a housing having first and second members for mounting said circulator, said members having opposIng flat parallel surfaces;

and wherein said first foil is positioned between said first driving member and said first element in a plane displaced from said parallel surface of said first housing member.

5. The combination of claim 4 wherein said first driving member is mounted against said parallel surface of said first housing member.