Abstract: A heat sink for a magnetically tuned filter provides an insulative gap between the magnetic coils and the magnetic housing and pole pieces and has a thermally conductive plate in thermal contact with the magnetic coils with a flange portion extending exterior of the magnetic housing so that heat generated by the magnetic coils is conducted for dissipation external of the magnetic housing. The thermally conductive plate has a central opening in which a filter housing is situated, has a plurality of channels between the central opening and the outer edge to provide for electrical and mechanical access to the filter housing, and has a radial insulative gap from the central opening to the outer edge to prevent the formation of eddy currents in the thermally conductive plate.

Abstract: A resonance system for ESR spectroscopy has a resonance cavity (23) which connected by axial slots (25) with chambers (24) coaxial to the resonance cavity (23). The resonance cavity (23) and the chambers (24) are located within a metallic screen (21). The wall sections (26) of the resonance cavity (23), separated by the axial slots (25), form the inductances of the resonance circuit, whereas the wall sections of the axial slots (25), located opposite one another, form the capacitances. The entire resonance system, including the screen, is made of metal and is, therefore, suitable for use at extremely low temperatures.

Abstract: A stripline filter resonator structure is provided which exhibits high Q and results in a filter with low insertion loss. The dielectric consists of two sections of dielectric material. A groove shaped as half an ellipse is formed in each of the sections. The surface of the grooves are covered with electrically conductive material. The two grooves are aligned and filled with adhesive material to hold the two dielectric sections together. An elliptically shaped resonator is thus formed in the center of the dielectric sandwich. Ground plane layers are respectively situated on the outer layers of the dielectric sandwich thus forming a stripline resonator structure. This unique resonator structure results in a more uniform current density around the periphery and thus undesired current bunching is correspondingly decreased.

Abstract: A uniform surface current density is approximated in an RF transmitting/receiving NMR coil by employing a plurality of discrete conductors having a resonantly distributed current. Inductive and capacitive lines provide a sinusoidal current distribution with various resonant modes providing different magnetic field orientations. The distributed current reduces losses. In a second order resonant mode, decoupling of the surface coil from a transmit coil is achieved without a blocking network.

Abstract: A resonator in which the input and output transducers are positioned to couple strongly into a resonant mode of interest. Signal drains are included to drain energy out of spurious resonant modes. In a magnetostatic wave resonator, the signal drains are preferably grooves in the surface of the ferrimagnetic film forming the resonator cavity.

Abstract: A magnetostatic wave structure in which magnetostatic wave signals are coupled between discrete magnetostatic wave elements without the use of microstrip transducers. This structure consists of a plurality of blocks of ferrimagnetic material in which each block has an edge close enough to an edge of another block that a magnetostatic wave in the first of these blocks couples across the gap between these two edges into the second of these blocks. Linear and nonlinear configurations are presented that include a band pass filter.

Abstract: A magnetostatic wave resonator having a transducer oriented such that it is tangent at all points to a wavefront of a traveling wave component of a resonant mode of the resonant cavity. In a rectangular cavity of width L.sub.x and length L.sub.y, the transducer is perpendicular to the wavevector k=(m.pi./L.sub.x)e.sub.x +(n.pi./L.sub.y)e.sub.y for some nonzero integers m and n, whereby the transducer optimally transfers energy into the resonant mode that is a linear superposition of travelling waves that includes this wavevector. This enhances coupling into the resonant mode of interest and reduces the amount of coupling into spurious modes.

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: An ESR spectrometer is equipped with a split-ring resonator comprising an electrically conductive cylinder or loop which may be excited by a microwave antenna. The conductive cylinder or loop is secured to a surface of an insulating sheet whereby the other surface may be brought to bear upon the specimen being examined. Preferredly, the insulating sheet comprises two insulating sheets with a Faraday shield sandwiched therebetween whereby the magnetic field generated by the microwave energy applied to the loop leaks to the surface of the specimen but the electric field is inhibited.

Abstract: Microwave filters which have the best electrical characteristics for small volumes are required in radio communications particularly in traffic broadcast communication links and the invention provides filters formed as comb line or interdigital line filters in which the inner resonator conductors are formed as flat spirals.

Abstract: A circularly polarized radio frequency probe for use in magnetic resonance systems, the probe comprises four effective "saddle coils" arranged to define a single cylinder. The saddle coils each comprise a pair of 120 degree arcuate conductor sectors separated by longitudinal conductors. RF power is coupled to each of said "saddle coils" so that first and second pairs of said saddle coils generate first and second fields normal to each other.

Abstract: A radio frequency coil for nuclear magnetic resonance imaging comprises at least one pair of arcuate H-shaped members which are disposed about a longitudinal axis so as to form a tube. A variable capacitor means for adjusting the resonant frequency of the coil is connected across the feeding points of the coil. A balanced feed circuit comprising a balanced impedance matching circuit and a balanced-to-unbalanced converter is connected across the feeding points. An unbalanced current from a transceiver is converted into balanced currents which are fed to the feeding points.

Abstract: A ferrimagnetic resonator is disclosed which is stabilized upon temperature deviation and operable over a wide frequency range. The resonator comprises a ferrimagnetic thin film resonance element, a temperature detector for the resonance element a bias magnetic field generating coil, a compensation coil and a compensation circuit. The compensation circuit has a pre-coded compensation data upon operation temperature range and generates a compensation signal in response a detected temperature of the resonance element. The compensation signal is then fed to the compensation coil to generate an additional magnetic field to the resonance element thus the resonance frequency of the resonance element is stabilized upon temperature.

Abstract: An overcoupled resonator having a resonant cavity defined by a thin film of magnetic material with a pair of end walls parallel to a transducer. Because this resonator is overcoupled, it is suitable for use in a broadband oscillator.

Abstract: A cavity resonator suitable for use in a high-speed nuclear magnetic resonance (NMR) imaging device comprises a plurality of transmission lines aligned parallel to a common axis and magnetically coupled to produce an essentially uniform dipole magnetic field perpendicular to the axis. The transmission lines are two conductor lines, with the first conductors being arranged inwardly of a second conductor common to all lines. The common conductor is symmetrically arranged about the axis of the resonator and constitutes a shield to contain the magnetic field within the cavity. The plurality of transmission lines are conductively isolated from each other but spaced in sufficiently close proximity to each to provide for strong mutual magnetic coupling amongst all transmission lines. A single inductive coupling loop may be provided for driving the resonator with a linearly polarized magnetic field and for receiving NMR information from the resonator. The use of a pair of inductive coupling loops spaced 90.degree.

Abstract: An Alderman high-frequency coil used for generating or detecting a high-frequency magnetic field in an NMR apparatus comprises two ring-shaped inner conductors aligned coaxially with a spacing being made therebetween and two outer conductors disposed to surround the inner conductors. The outer conductors are each split along the current path to form a 4-piece outer conductor.

Abstract: A YIG film microwave device utilizing the ferrimagnetic resonance of a YIG film, comprising a YIG film microwave element formed by a liquid phase epitaxial growth process and a photolithographic process, and a magnetic circuit including permanent magnets for applying a DC magnetic field to the YIG film microwave element. Some of the Fe.sup.3+ ions of the YIG film are substituted by nonmagnetic ions to provide the YIG film microwave device with satisfactory temperature characteristics. The YIG film microwave device is capable of operating stably over the wide range of working frequency and that of temperature.

Abstract: A magnetostatic wave tunable resonator which has fine stripe electrodes and bonding electrode films formed on the surface of a YIG thin film supported by a GGG substrate. The stripe electrodes, bonding electrode films and edges of the YIG film are formed by a chemical etching method based on photolithography. The resonator so formed has suppressed spurious resonance of high order modes and enables the use of a magnet of greatly reduced size.

Abstract: To improve the space factor of a barium titanate resonator, the resonator is a tubular carrier (11) having metal layers on the inner and outer surfaces. At least one of the metal layers is axially interrupted by a slit. Terminal connections for the resonator are located adjacent the slit on the interrupted layer, and on the continuous layer. For shielding, preferably, the continuous layers at the outside and end tabs (FIG. 4) may additionally be provided. More than one axially staggered inner/outer electrode layer system may be provided on one tubular carrier.

Abstract: A resonator coil assembly (32) includes a dielectric sleeve (40) on which a first resonator coil portion (42) and a second resonator coil portion (44), each of copper foil, are adhered. The dielectric sleeve is dimensioned to receive a human torso therein and in one embodiment (FIG. 1) is circular in cross section and in another (FIG. 4) is elliptical in cross section. A pair of adjustable tuning capacitances (64, 66) and a pair of adjustable matching capacitances (68, 70) are interconnected between one end of the each coil portion and a metal bore liner (54). An opposite end of the coil portions are capacitively coupled to each other (FIG. 1) or to the bore liner (FIG. 3). A half wave length cable (72) interconnects the junctions between the first and second tuning and matching capacitances. One of these junctions is connected by a cable (74) with a radio frequency generator (30) and a radio receiver (34).

Abstract: Disclosed is a magnetic resonance imaging apparatus, with an r.f. coil which is designed on the basis of the sinusoidal current distribution across a circular-cylindrical surface about a central coil axis and which is, subject to a generally applicable looping-through condition z.sub.1 =-K z.sub.2, when K is a positive constant which depends on the number of bars and geometrical deviations, z.sub.1 is the impedance of the bar conductors, and z.sub.2 is the impedance of ring conductor elements between each two pair of bar conductors. The coil based on the above condition is particularly adapted to parasitic capacitances of the bar conductors and to the general shape of objects to be examined.

Abstract: A local coil assembly for use in NMR imaging includes a base which supports a pair of spaced local coil modules. The size and separation of the local coil modules can be changed without affecting the resonant frequency of the assembly. Each local coil module includes a pair of loop-gap resonators, and the base provides the electrical interconnection of the loop-gap resonators in each module.

Abstract: A dielectric resonator comprises a shield electrode defining a resonant space and cylindrical dielectric resonator element disposed and supported fixedly in the resonant space, to which an input and output are coupled. Into the hollow portion of the dielectric resonator element, a tuning unit made of a dielectric material is inserted so as to be displaceable in an axial direction therein. The tuning unit is coupled to a supporting axis which is displaceable axially, thus causing the tuning unit to displace in that direction. A resonance frequency of the dielectric resonator varies as the tuning unit displaces.

Abstract: A dielectric resonator employing the TM mode as its resonance mode, which is provided with a dielectric base plate on which an electronic circuit is formed and a pair of electrodes formed in face-to-face relation to each other on respective major surfaces of the dielectric base plate. A plurality of through-holes are defined between the pair of electrodes on their circumferential portions and both of the electrodes are connected with each other by way of conductive material formed on the inner surfaces of the through-holes.

Abstract: A local coil for use in NMR imaging includes a pair of loop-gap resonators which are geometrically arranged to be intrinsically isolated. The local coil also includes passive decoupling means to completely decouple the local coil during excitation. In a first embodiment, the pair of loop-gap resonators are disposed axially and the passive decoupling means comprises a pair of back-to-back diodes across the loop-gap resonators. In a second embodiment, the pair of loop-gap resonators are disposed in a plane and the passive decoupling means comprises two single turn loops inside each loop-gap resonator with back-to-back diodes across an open segment of each single turn loop. During excitation, the diodes fire thereby lowering the Q and shifting the resonant frequency of the local coil. Using a combination of intrinsic isolation and passive decoupling, the local coil is completely decoupled from the excitation field.

Abstract: A local probe for use in nuclear magnetic resonance imaging includes a pair of loop-gap resonators which are connected together and positioned adjacent a region of interest. FID signals produced in the region of interest induce signals in coupling loops mounted near each loop-gap resonator, and these connect to a transmission line leading to the receiver. Three embodiments are disclosed, one best suited for imaging appendages, a second best suited for imaging the head and neck, and a third best suited for the spine.

Abstract: A stripline filter includes a cylindrical substrate made of a dielectric material and having inner and outer surfaces with opposite ends thereof opened. A ground electrode is deposited on the inner surface, and on the inner surface, interdigitated electrodes are deposited. Alternately, the ground electrode may be deposited on the outer surface, and the interdigitated electrodes may be deposited on the inner surface. Thus, the stripline filter can be arranged in a compact size. Also, the ground electrode provided on the outer surface prevents electromagnetic waves generated from the interdigitated electrodes from being emitted out.

Abstract: Counter Rotating Current (CRC) pairs of loop-gap resonators are combined with planar pairs of loop-gap resonators to form networks of NMR local coils. A first embodiment is a quadrature probe in which a planar pair is sandwiched between the loop-gap resonators of the CRC pair. In a plurality of other embodiments, CRC pairs, planar pairs, and other types of local coils are arranged adjacent to one another to form networks of NMR local coils with an enlarged net region of sensitivity.

Abstract: A radio frequency coil for a nuclear magnetic resonance imaging apparatus comprises a plurality of arcuate, plate-like H-shaped members which are disposed about a common axis so as to form a tube. The flanges of adjacent H-shaped members are electrically connected. The web of at least one of the H-shaped members is cut in two at its midportion to form two T-shaped plates, and the legs of the T-shaped plates are connected by capacitive coupling in a manner which allows the capacitance to be varied. A conventional variable capacitor can be used to vary the capacitance. Alternatively, each H-shaped member is divided into two T-shaped plates with overlapping legs. A dielectric material is provided between the overlapping portions, and the capacitance is varied by moving the T-shaped plates with respect to one another in the longitudinal direction of the tube so as to vary the size of the overlapping portions.

Abstract: The prior art split-ring resonator for use in an electron spin resonance (ESR) spectrometer comprises a circular cylinder made from an electrically conductive material and housed in a metallic tube. The cylinder is provided with a split extending axially of the cylinder. A sample to be investigated is inserted into the cylinder in the axial direction. In accordance with the invention, a shielding member which is wider than said slit and made from an electrically conductive material is disposed so as to shield the slit from the inside of the cylinder, whereby the resonance frequency of the resonator is not significantly affected by the presence or absence of the sample or by the amount of the inserted sample.

Abstract: A directional filter wherein dielectric resonators tuned to the operating frequency couple electric energy from port one to port four while electrical energy at other frequencies passes through the filter to port two.

Abstract: An R.F. coil system is described for generating and/or receiving at least substantially homogeneous alternating magnetic fields, notably in nuclear magnetic resonance apparatus. The system is arranged about an essentially cylindrical examination space and comprises at least four conductor segments which are oriented essentially parallel to the longitudinal central axis of the examination space. The conductor segments are arranged about the circumference of the examination space symmetrically with respect to at least one plane which extends through the longitudinal central axis and are interconnected so as to form a closed loop. The conductor segments which receive a current of the same sense with respect to the longitudinal axis, are interconnected at neighboring ends by conductor elements which are oriented essentially in the circumferential direction of the examination space so as to form conductor groups.

Abstract: A dielectric resonator provided with a plurality of dielectric resonator units which are combined into one unit, with a boundary being formed between adjacent dielectric resonator units, a connecting material for rigidly connecting said adjacent dielectric resonator units to each other, a support member for placing said dielectric resonator units thereon, a metallic conductive case accommodating said dielectric resonator units on said support member therein, and input and output members for electrical connection of said dielectric resonator with an external circuit, whereby a resonant frequency of spurious mode is shifted into a frequency zone higher than a resonant point by causing said spurious mode to pass through boundary surfaces or layers.

Abstract: A microstrip antenna or other microstrip device has a planar electrically-conductive region on the surface of a dielectric board. The device is tuned by silk-screen printing one or more layers of a dielectric ink/paint over the surface of the device. This produces layers of a predetermined thickness which each reduce the frequency of tuning of the device by a predetermined amount until the desired frequency is achieved.

Abstract: A stripline tapped-line filter is disclosed including a first substrate upon which a plurality of N hairpin resonators are disposed alternately on opposite surfaces of the first substrate. Each one of the hairpin resonators is in a parallel coupled relationship with an adjacent hairpin resonator disposed on an opposite surface of the first substrate. The first and last hairpin resonators each have an interconnected member disposed on the substrate for respectively coupling a signal into and out of the plurality of N hairpin resonators. Second and third substrates are included with each being respectively located adjacent to ones of the plurality of N hairpin resonators on opposite surfaces of the first substrate. First and second groundplanes are included with each respectively located adjacent the second and third substrates.

Abstract: Disclosed herein is a magnetic apparatus comprising: a magnetic circuit including magnetic yoke and a magnet, with a magnetic gap formed in the circuit for forming a uniform d.c. bias magnetic field in the magnetic gap; a magnetic device made of magnetic material of certain composition and placed in the magnetic gap so that the device operates in the d.c. bias magnetic field; and a soft magnetic plate provided in the magnetic gas, the soft magnetic plate being made of magnetic material having composition substantially identical to the composition of the magnetic device.

Abstract: A helical resonator comprises an insulating body portion having therein a cavity. In one embodiment, a helical conductor is formed on the inside wall of the cavity and another conductor is formed on the outside of the insulating body. In another embodiment, the helical conductor is formed on the outside of the insulating body and the other conductor is formed on the outside wall of the cavity. In a preferred embodiment, the disclosed helical resonator is formed as an integral part of the body of a signal coupler for coupling an antenna to a tuner and electrically forms a series tuned trap connected between conductors of the signal coupler.

Abstract: An identification device in the form of a tag-like strip, affixable to an article, for use in an electronic security system comprising opposingly situated conductor strip portions which may be punched out of a metal foil. The conductor strip portions are folded together along suitably positioned fold lines so that mutually superposed conductor strip portions form an uninterrupted winding of inductive elements having a dielectric positioned therebetween. The conductor strip portions can be fabricated on continuous roll and separated by transverse perforations.

Abstract: A dielectric resonator device includes a casing for defining a chamber in which a dielectric resonator and a piezoelectric frequency adjusting unit are provided. A portion of the piezoelectric frequency adjusting unit is located adjacent the dielectric resonator. By the voltage applied to the piezoelectric frequency adjusting unit, the piezoelectric frequency adjusting unit changes its shape thereby changing the distance between the portion of the piezoelectric frequency adjusting unit and the dielectric resonator. Thus, the resonance frequency of the dielectric device can be controlled.

Abstract: A dielectric resonator microwave bandpass filter includes a printed circuit board supported within a cut-off waveguide, with dielectric resonators and coupling loops on an upper surface of the board and a well beneath the board so that the resonators are well spaced from ground planes. Tuning screws beneath the resonators, and coupling adjustment screws above the board adjacent to the coupling loops and between adjacent resonators, provide for adjustments to provide desired filter characteristics within a wide range. Isolators within the waveguide have ports coupled to the resonators via microstrip transmission lines comprising conductive tracks on the board and ports coupled to coaxial connectors in end walls of the waveguide. The waveguide is formed from a cast body and a flat lid.

Abstract: A helical filter is disclosed which includes a ground plane having microstrip transmission line segments to which a respective helical resonator coil is connected at the high impedance end thereof. A discrete capacitor is connected in parallel with each transmission line. A housing is provided with individual resonator compartments which effect associated distributed capacitance with the resonators themselves, which capacitance may be adjusted by included tuning screws. Conductors are connected to and form an integral part of a given two of said transmission lines and serve as the input and output for the helical filter. The transmission line and discrete capacitor pair provides the necessary impedance match, while the capacitor itself facilitates temperature compensation and frequency range selection.

Abstract: A ferromagnetic resonator comprises a nonmagnetic substrate, a ferrimagnetic thin film element formed on a major surface of the nonmagnetic substrate, a strip line for example formed on another major surface of the nonmagnetic substrate and electromagnetically coupled to the ferrimagnetic thin film element, a conductive wall facing the strip line and spaced therefrom a predetermined distance, an end of the strip line being connected by the conductive wall to ground potential and a bias magnetic field source applying a D.C. magnetic field to the ferrimagnetic thin film perpendicular to the major surface thereof. Such an arrangement enables a drastic reduction in the effective dielectric constant of the transmission lines, whereby a filter with a high center frequency of the order of at least ten gigahertz can be achieved despite the short type structure.

Abstract: An oscillator with a dielectric resonator capable of providing a designated output and being suited for mass production comprising an insulating substrate, a strip structure, a dielectric resonator located adjacent to the strip structure, the last two being mounted on the substrate, and an oscillatory transistor connected to one end of the strip structure. The strip structure consists of two spaced strip sections interconnected by an electrically-conductive bridge-shaped connector section having a conductor part, which is located further away from the insulating substrate and closer to the dielectric resonator than the two strip sections.

Abstract: An improved dielectric resonator for high frequency operation having improved unloaded Q is provided which is prepared by forming a first copper coating on the ceramic body to a thickness of 0.2 to 1 .mu.m by electroless plating or vacuum deposition, electrolytic plating a second copper coating on the first coating to a thickness of at least two-fold of the skin depth, and heat treating the thus coated body at 120.degree.-300.degree. C. in a reducing atmosphere or at 700.degree.-1080.degree. C. in a weakly acidic atmosphere.

Abstract: A microwave resonance circuit device including plural microstrip lines provided on one side of a dielectric substrate. A dielectric resonator is mounted on the reverse side of the substrate from the microstrip lines and is disposed so as to have a coupling relation with a first one of the microstrip lines. A ground conductor is arranged on the reverse side of the substrate so as to overlap substantially one-half of the width of the first microstrip line extending in a direction away from the dielectric resonator, and to overlap entirely the other microstrip lines. A transistor is mounted on the same side of the substrate as the microstrip lines and connected therewith to form an oscillator circuit.

Abstract: A microwave bandpass filter having a wide bandwidth, low loss, and yet which requires only a relatively small circuit area. A generally annularly shaped unit-wavelength resonator is formed on a dielectric substrate, disposed between input and output matching circuits. The unit-wavelength resonator is formed by a pair of semi-annular strips disposed opposite one another and having opposing stubs defining therebetween a gap of predetermined width.

Abstract: A dielectric resonator is disclosed which includes a case having a resonator main body portion, an upper lid and a lower lid. Inside the case is a cylindrical dielectric material. The case is formed of a dielectric material having the same coefficient of linear expansion as the cylindrical dielectric material. In one embodiment, main body portion comprises a dielectric case side portion with the cylindrical dielectric material disposed concentrically in a concavity defined by the case side portion, with the cylindrical dielectric material being integrally coupled to the dielectric case side portion by four connecting portions. More specifically, in this embodiment, the case side portion of the main body portion and the cylindrical portion are simultaneously and integrally formed of the same dielectric material. A conductive film is formed to enclose a region surrounding the cylindrical dielectric material.

Abstract: A cavity resonator serves to generate magnetic dipole transitions in a sample, for instance for carrying out electron spin resonance measurements. The natural frequency of the cavity resonator (10) is influenced by a reduction in length of the E flux lines. To this end, conductive areas (20) are arranged at the points where the E flux lines are encountered. This results in an increase of the space factor, related to an unchanged specimen volume, and thus in an improvement of the measuring sensitivity.

Abstract: An improved loop coupled YIG resonator has a coupling loop of three sections, a loop section partially encircling a YIG resonator, and two straight end sections. The end sections together with a ground plane enclosing one end of the resonator cavity form a transmission line, the characteristic impedance of which is determined by the distance of the end section above the ground plane. The characteristic impedance is chosen to match the transmission line input to which the coupling loop is connected.

Abstract: A ring shaped dielectric resonator tuned by inserting a bolt from below the resonator into an opening of the resonator. The bolt causes the dielectric constant of the opening to change. The change in the dielectric constant changes the electric field which in turn changes the magnetic field of the resonator.