Patent ID: 7609124

Claim:
A non-reciprocal circuit device comprising: a metal case; a ground plate disposed on an inner bottom surface of said metal case; a resin member disposed on said ground plate and having an opening from which said ground plate is exposed; a planar microwave ferrite member disposed in the opening of said resin member and having a thickness, a strip line member disposed on said planar microwave ferrite member; and a ferrite permanent magnet disposed via an air layer on said strip line member without another planar microwave ferrite member and another ground plate therebetween; wherein said strip line member comprises a connecting portion constituted by strip electrodes radially extending from a center portion, branch lines radially extending from said center portion between said strip electrodes, low-impedance lines each integrally connected to each of said branch lines and extending along the periphery of said planar microwave ferrite member, and input/output electrodes each integrally connected to an outer side of each of said low-impedance lines, whereby said branch lines and said ground plate form microstrip lines, and said low-impedance lines and said ground plate form a grounded capacitor, said grounded capacitor acting as a matching circuit, and wherein a gap between said strip line member and said ferrite permanent magnet is within a range of 1 to 3 times the thickness of said planar microwave ferrite member.