Abstract: The performance of broadband isolators and circulators can be characterized by the ratio fmax/fmin, where fmin and fmax are defined as the edges of the frequency band in which the devices have acceptable operating characteristics. For the most advanced isolators and circulators available today this ratio is approximately 3:1. This invention teaches how to improve broadband performance substantially. The present limitations are shown to be primarily due to two causes: 1.) lack of bias field homogeneity, and 2.) previously unrecognized low-field loss due to excitation of magnetostatic surface waves. These surface waves are excited at the dielectric/ferrite interfaces on the side faces of the ferrite platelets or discs in the devices. For stripline edge-mode isolators and stripline circulators, the undesired low-field loss can be reduced by using certain rf device structures in combination with suitable bias magnets.

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 miniature circulator which is microwave integrated circuit compatible and based on microstrip transmission techniques is described. The circulator includes a dielectric or semiconductor substrate having microstrip transmission lines formed thereon and a patterned metalization formed as the node metalization for the circulator. The substrate may carry other circuits such as power combiners, amplifiers, and switches. The substrate further includes monolithic capacitors over the substrate at the center of the circulator in a first embodiment or disposed along the periphery of the patterned metalization in the second embodiment. The capacitors are used to capacitively couple the patterned metalization or node metalization to the ground plane conductor. The value of capacitance is selected to provide value broadband performance.

Abstract: A random-access memory having a plurality of memory cells each cell including a magnetic storage element in which the magnetic storage element inlcudes a thin film of magnetic material disposed on a semiconductor substrate and having further disposed thereon transistors connected in a flip-flop type of configuration. In a preferred embodiment of the invention, the magnetic storage element comprises a thin magnetic film that has mutually orthogonal remanent magnetization states used for information storage. A pair of strip conductors used to provide connections to the flip-flop configuration of the transducers are magnetically coupled to the mutually orthogonal remanent magnetization states. By providing the thin film having a pair of mutually orthogonal remanent states used for information storage, a storage cell having a relatively high frequency response is provided.

Abstract: Integratable microwave devices such as a tuneable band reject filter or an r.f. switch are provided on a gallium arsenide substrate having a (100) orientation. Each of the devices includes a layer of a ferromagnetic material having a pair of easy axes which lie in the plane of said (100) orientated substrate and a layer of a conductive, nonmagnetic material disposed thereover. The ferromagnetic material has a ferromagnetic resonant frequency related to the applied DC magnetic field, the anisotropy field, the saturation magnetization, and gyromagnetic ratio. Such devices are provided by utilizing the ferromagnetic resonant properties of the ferromagnetic material disposed on the (100) substrate.

Abstract: A materials separator apparatus comprising a base supporting a ramp type of materials receiving surface sloped longitudinally and transversely with respect to the base for directing commingled dielectric items and electrically conductive items of nonferromagnetic materials deposited on its upper end portion along a fall path extended longitudinally and transversely downward of the surface, and a planar series of substantially parallel permanent bar magnets supported in contiguous rows in a plane substantially parallel to the material receiving surface and sufficiently close thereto for establishing along the surface a spatially alternating array of oppositely directed static magnetic fields which extend in substantially parallel relationship transversely of the surface at an oblique angle with the fall path of the commingled items.

Abstract: A stripline circulator includes a pair of dielectrically supported ferrite discs and a pair of spaced hemispherical ferrite caps each one disposed over a corresponding one of the ferrite discs. The ferrite caps provide in combination with the ferrite discs a uniform DC magnetic field within the ferrite discs to reduce the insertion loss of the circulator at frequencies less than the so-called magnetization frequency of the ferrite material and thus, extend the operating bandwidth of the circulator. The ferrite caps are spaced from the ferrite discs by a thin layer of metallization having a thickness larger than the skin depth thickness of a microwave signal over the desired microwave frequency band. The ferrite discs are preferably comprised of signal crystalline ferrite materials oriented in a hard-axis orientation which generally is the [100] direction for materials where the first order anisotropic constant K.sub.1 is negative.

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 having a resonant frequency which is substantially invariant with external applied static and dynamic stresses is provided. The magnetically tuned resonant circuit includes a housing which provides a magnetic flux return loop. A central post of the magnetically tuned resonant circuit includes a pair of pole pieces, upper and lower portions of the housing, a magnet and an RF structure. The RF structure including a pair of coupling loops and a YIG sphere disposed between the coupling loops is disposed between the pair of pole pieces. In a first embodiment, the elastic compliance of the center post portion of the magnetically tuned resonant circuit is increased by a predetermined amount by providing a nonmagnetic collar around a first one of the pole pieces disposed between said pole piece and the RF structure.

Abstract: An apparatus and method for selectively orientating a ferrimagnetic body along a selected temperature invariant crystallographic axis includes a first pair of coils disposed for producing a magnetic field along a first direction, and a second pair of coils disposed within the first pair of coils for producing a magnetic field along a second direction, the direction of such second field being displaced at a predetermined angle .theta., with respect to the direction of said first field. A platform upon which the ferrimagnetic body is supported is disposed at an intersection of such fields and has a surface disposed at a predetermined direction with respect to a horizontal plane. A series of alternate pulsed magnetic fields is generated in turn by each pair of coils and the body rotates in response to each one of such fields. After pulsed fields have been generated, the so-called "easy axis" of the crystallographic structure of the body is aligned with the axis of the coils.

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: A magnetically tuned resonant circuit for selectively coupling radio frequency (r.f.) energy between an input coupling circuit and an output coupling circuit, dielectrically spaced from the input coupling circuit, through a resonant body disposed therebetween. Each coupling circuit includes a center strip conductor portion dielectrically spaced from a ground plane conductor. Such center strip conductor and ground plane conductor of each coupling circuit are formed on a common surface of a corresponding dielectric. The center strip conductor portions are orthogonally orientated, and have first end portions which are coaxially aligned and terminated with the ground plane. The resonant body is dielectrically supported between each one of such first end portions of such center conductors.

Abstract: Magnetographic printing apparatus having scan magnetization of the recording surface. A bubble plate is provided adjacent the recording surface upon which bubble magnetic domains are propagated in a direction perpendicular to the direction of movement of the recording medium. A row of electromagnetic recording heads on the opposite side of the recording medium from the bubble plate are energized to produce a magnetic field which, when added to the magnetic field of the bubbles, is sufficiently high to cause magnetization of selected portions of the recording medium. In a second embodiment, a belt having magnetically permeable vanes mounted thereon is positioned on the side of the recording medium opposite the electromagnets. The vanes concentrate the magnetic field from the electromagnets to a sufficiently high value to magnetize the recording medium.

Abstract: A high capacity materials separation apparatus including a conductive metals segregator in the form of a magnetic ramp for receiving commingled materials from an air classifier, the air classifier comprising means for separating materials into heavy and light fractions, and means for maintaining positive air pressure within the classifier for propelling the nonmagnetic heavy fractions at accelerated velocity from the classifier so as to achieve high capacity separation of conductive materials at the ramp.

Abstract: An ink feed system for an electrophoretic printer wherein a ribbon is used to carry ink from an ink supply to the paper upon which it is applied by means of an electric field. A magnetic constituent is added to the ink and a magnetic field is impressed alongside the ribbon and parallel to the surface thereof. A Hall probe positioned in the magnetic field senses perturbations thereof perpendicular to the ribbon induced by the presence of ink on the ribbon. A signal produced by the Hall probe signals the density of the ink upon the ribbon and is utilized for regulating a flow of ink onto the ribbon.

Abstract: Materials separating apparatus comprising an inclined drum rotatable about its longitudinal axis and having an inner surface comprised of an array of permanent magnets arranged in parallel strips extending circumferentially at an angle to the drum axis, and means for depositing commingled materials within the drum upon the magnet array whereby as the drum and magnet array rotate the magnetic field of the magnets will induce eddy currents in conductive items causing them to move progressively upward and out the upper end of the drum, while nonconductive items will slide downwardly out the lower end of the drum. In another embodiment of the invention a liner is provided over the magnet array to carry magnetic items upwardly to be deposited separately in a chute or the like.

Abstract: A materials separator for segregating nonferromagnetic conductors from commingled nonferromagnetic materials, the separator including guide means for directing nonferromagnetic materials into a stream, and steady-state magnetic means comprising a plurality of north and south magnetic poles arranged in stripes of alternating polarity at a substantially uniform angle to the stream for establishing in the path of the stream a periodic series of oppositely directed, static magnetic fields which induce eddy-currents in the conductors.

Abstract: A multicolor magnetographic printing system wherein a magnetizable surface is recorded upon with a different recording wavelength for each color to be printed. Toner is supplied which includes a mixture of different types of particles, each having a different color. The differently colored particles each maximally adhere only to areas on the surface recorded at a wavelength specific for the particular particle type. The toner particles are varied in magnetic susceptibility as well as linear dimensions so as to adjust their maximum adherence for the particularly matched wavelength. Such a system may further include an image enhancement system to ensure that the proper toner particles are concentrated in the appropriate areas. The toner is transferred to a paper surface by both preheating the paper before transfer and heating it afterwards to fix the toner onto the paper surface.