Microwave circulator with a planar, biasing, permanent magnet

Abstract

A microstrip circuit having a plurality of coplanar microstrips mounted on a common dielectric substrate. A planar circulator is coupled to a junction of the microstrips. The circulator includes a ferrite disc which lies in the plane of the substrate. The circulator also includes a biasing permanent magnet in the form of a planar, toroidal-shaped magnet having magnetic sections that are embedded in the dielectric substrate. The magnetic sections from a split cylinder that encircles the ferrite material while permitting the microstrips to pass therethrough.

What is claimed is: 
     
       1. A microstrip circuit a conductive ground plane;   a dielectric substrate mounted on the conductive ground plane   a plurality of flat conductive microstrips mounted in a common plane on the dielectric substrate;   a region of ferrite material displaced within the dielectric substrate beneath a portion of each of said conductive microstrips; and   a biasing permanent magnet positioned within the dielectric substrate such that the permanent magnet encircles the region of ferrite material.   
     
     
       2. The circuit of claim 1 wherein the biasing magnet includes a plurality of magnetic sections positioned in a toroidal-shape region encircling the region of ferrite material. 
     
     
       3. The circuit of claim 2 wherein the region of ferrite material is a ferrite disc. 
     
     
       4. The circuit of claim 3 wherein said magnetic sections form a split cylinder having a plurality of slots and wherein each of said strips is located in the plane of a different one of said slots.