Abstract: A miniature circulator which is compatible with integrated circuits is described. The circulator includes a substrate which supports three copolanar waveguide transmission lines which are connected at a common junction. The common junction provides a coupling structure between the coplanar waveguide transmission lines. A ferrite disc having a conductive layer disposed thereover is provided over the intersection of the three coplanar waveguide transmission lines. A magnet is then disposed over the ferrite disc to direct a D.C. magnetic field through the disc. An alternative coupling structure having interwoven, balanced lines disposed on the substrate is also described. An alternative arrangement for the ferrite disc having a hexangular shape, which carries a beam-lead node metalization is also described.

Abstract: A magnetically tuned resonant circuit having improved noise performance includes a ferrimagnetic or gyromagnetic body such as a YIG sphere which is disposed within r.f. structure, The r.f. structure is disposed between a pair of pole pieces of a biasing magnet and flux return path. Several techniques are described for reducing fluctuations in magnetic fields through the gyromagnetic body. The gyromagnetic body is isolated from conductive surfaces, or the bulk of conductive surfaces in the region adjacent to the magnetic body are reduced. Further, a technique is also described which provides a break in the electrical continuity around the r.f. structure. Each of these technique reduce the magnitude of thermally induced eddy current flow in conductive regions adjacent to the resonant body. It is believed that such eddy current flow produce random magnetic field variations which produce random variations in the frequency characteristics of conventional magnetically tuned resonant circuits.

Abstract: A magnetically tuned resonant circuit for coupling r.f. energy between input and output coupling circuits thereof in a first mode of operation and isolating such energy between such coupling circuits in a second mode of operation includes a current path circuit provided to selectively change the resonant frequency of the magnetically tuned resonant circuit. In a first embodiment of the current path circuit, a microstrip transmission line used to form one of such coupling circuits, having a pair of planar spaced strip conductor portions adjacent a resonant body, is configured to provide the current path around such body. In the presence of an external magnetic field H.sub.DC, a pulse of current is fed around the current path and in response thereto provides a pulse magnetic field H.sub.DCp in the region of the resonant body. Such field H.sub.DCp either aids or opposes the external magnetic field H.sub.DC and in response thereto shifts a resonant frequency .omega..sub.

Abstract: A magnetically tuned resonant circuit for selectively coupling radio frequency (r.f.) energy between an input coupling circuit and an output coupling circuit through a resonant body disposed between such coupling circuits. Each coupling circuit includes a plurality of spaced conductors which are arranged to selectively spatially distribute r.f. energy fed thereto in order to provide, in the region where the resonant body is disposed, a magnetic field having a predetermined spatial distribution. Such magnetic field distribution is selected in accordance with characteristics of the resonant body to reduce coupling of unwanted spurious r.f. energy through the magnetically tuned resonant circuit.Further, a ground plane conductor associated with such coupling circuits has a selected portion thereof removed to provide a void therein, and a portion of the resonant body is disposed within the void provided in the ground plane. The size of the void is selected to increase coupling of r.f.

Abstract: An impedance matching network for coupling a microwave transmission line to a field effect transistor (FET). The impedance matching network includes a resistor coupled in shunt with the FET and an inductor connected between the microwave transmission line and the resistor. The inductor is formed by wrapping a conductive wire around a post inserted into a hole formed in a support for the FET.