Abstract: A quantum computer, quantum logic circuit, material for forming qubits, and method of operating a quantum computer is described. The material is formed from a quasicrystal or quasicrystalline approximant. In some examples, topological quantum computing is performed based on the quasicrystal or quasicrystalline approximant materials. Quasicrystals and quasicrystalline approximate materials have materials properties that can be adapted to perform quantum computing. In one example, the material is a Tsai-type quasicrystalline approximant with a material structure selected to permit qubits to be generated.

Abstract: The present disclosure relates to an oscillator device (15) comprising an amplifier unit (16) and a tunable waveguide resonator (1) which in turn comprises a rectangular waveguide part (2) having electrically conducting inner walls (3) and a first waveguide port (4). The amplifier unit (16) is arranged to be electrically connected to the waveguide resonator (1) via the first waveguide port (4) by means of a first connector (17). The waveguide resonator (1) comprises at least one tuning element (6) positioned within the waveguide part (2), wherein each tuning element (6) comprises an electrically conducting body (7) and a holding rod (8a, 8b). The holding rod (8a, 8b) is attached to the electrically conducting body (7) and is movable from the outside of the waveguide resonator (1) such that the electrically conducting body (7) can be moved between a plurality of positions within the waveguide part (2) by means of the holding rod (8a, 8b).

Abstract: An automated trading exchange having integrated quote risk monitoring and quote modification services. An apparatus is implemented using at least one computer, having memory, and a processor. The computer is configured to receive orders and quotes, wherein specified ones of the quotes are contained in a quote group, and have associated trading parameters such as a risk threshold. Not all received quotes are required to have trading parameters as described herein. Preferably, the quote group contains all the quotes, or a subset of quotes, belonging to an individual market-maker for a given class of options contracts, or possibly the quotes of two or more market-makers that have identified themselves as belonging to a group for the purposes of risk monitoring and quote modification. The computer typically generates a trade by matching the received orders and quotes to previously received orders and quotes, and otherwise stores each of the received orders and quotes if a trade is not generated.

Abstract: An embodiment filter including metallic plating unitarily forming a spherical shell and a resonator, the resonator defining a resonator cavity, a tuning nut disposed in a lower portion of the resonator cavity, and a tuning screw threadably secured within the resonator cavity by the tuning nut, the tuning screw rotatable to deform an upper portion of the resonator to tune the filter.

Abstract: A radio frequency (RF) filter includes an input port configured to receive a signal, an output port configured to output a signal, and a tuning probe configured to be movable within a tuning probe port to adjust filter characteristics. The tuning probe port is configured to receive the tuning probe therein, and a locking mechanism is configured to lock the tuning probe in the tuning probe port at a desired depth and further configured to prevent movement of the tuning probe in the tuning probe port when the locking mechanism is in a locked configuration.

Abstract: Tunable MEMS resonators having adjustable resonance frequency and capable of handling large signals are described. In one exemplary design, a tunable MEMS resonator includes (i) a first part having a cavity and a post and (ii) a second part mated to the first part and including a movable layer located under the post. Each part may be covered with a metal layer on the surface facing the other part. The movable plate may be mechanically moved by a DC voltage to vary the resonance frequency of the MEMS resonator. The cavity may have a rectangular or circular shape and may be empty or filled with a dielectric material. The post may be positioned in the middle of the cavity. The movable plate may be attached to the second part (i) via an anchor and operated as a cantilever or (ii) via two anchors and operated as a bridge.

Abstract: A microwave resonant cavity includes a conductive shell with a screw hole having first threads and a screw having second threads configured to engage with the screw hole. The conductive shell defines a volume, the screw extends into the volume, the microwave resonant cavity has a resonant frequency, and the movement of the screw changes the resonant frequency. The first threads have a first pitch, and at least a portion of the second threads has a second pitch different from the first pitch.

Abstract: A tunable cavity resonator includes a substrate, a cap structure, and a tuning assembly. The cap structure extends from the substrate, and at least one of the substrate and the cap structure defines a resonator cavity. The tuning assembly is positioned at least partially within the resonator cavity. The tuning assembly includes a plurality of fixed-fixed MEMS beams configured for controllable movement relative to the substrate between an activated position and a deactivated position in order to tune a resonant frequency of the tunable cavity resonator.

Abstract: A linear actuator includes a drive arm and an extension arm each extending along a common drive axis. One of the arms has a plurality of resiliently deformable fingers extending beyond the end of the arm towards the other arm. At least one of the fingers has a thread on its inner face while the other arm has a threaded portion. At least part of the threaded portion is received between the fingers. The fingers are adapted to urge the threads of the two arms into interengagement such that rotation of the drive arm about the drive axis displaces the extension arm along the drive axis. The two threads are arranged such that when the ridge of one thread is received in the groove of the other thread the two sides of the ridge abut the two edges of the mouth of the groove.

Abstract: An on-axis rf power coupler for a superconducting particle accelerator includes a coaxial coupler tube that passes through a rf waveguide stub connected to a rf power source. The coupler tube is movable in translation along the axis of the beam path by a piezoelectric drive to permit variation of the coupling between the rf power source and the resonant signal in the accelerator. A tubular rf window extending through the waveguide stub, together with a vacuum bellows assembly connected to the coupler tube, isolate the vacuum inside the accelerator cavity from the vacuum in the rf waveguide and stub. A choke joint in the wall of the waveguide selectively passes unwanted HOM signals out of the waveguide stub and away from the accelerator cavity, where they are dissipated by ferrite tiles on the coupler tube. The upstream end of the coupler tube and a tubular extension of the accelerator cavity form a coaxial line for introducing rf power into the accelerator.

Abstract: A tunable cavity resonator includes a housing, a post, and a controllably variable capacitive coupling. The housing defines an interior and has at least one side wall, a first end, and a second end. The post is located within the interior and extends from the first end to the second end. The post and the housing define a resonating cavity. The controllably variable capacitive coupling is disposed in the housing.

Abstract: The present invention is directed to a piezo-electrically actuated membrane (ex.—a tuner) configured for use with a tunable cavity filter. The piezo-electrically actuated tuner may be formed of printed circuit board materials and may be placed over the cavities of the tunable cavity filter. Further, the piezo-electrically actuated tuner may promote high level performance of the tunable cavity filter, while allowing the tunable cavity filter to be tunable across wide bands.

Abstract: This disclosure provides implementations of electromechanical systems (EMS) resonator structures, devices, apparatus, systems, and related processes. In one aspect, a method includes providing a first substrate and a second substrate. In some implementations, the first substrate includes a cavity ceiling, an array of dielectric spacers, and an assembly platform arranged adjacent the array of dielectric spacers opposite the cavity ceiling surface. The assembly platform includes a plurality of post tops. In some implementations, the second substrate has an array of cavities and an array of resonator posts. In some implementations, the method includes mating the first substrate with the second substrate, connecting the post tops with the posts to form an array that includes a plurality of evanescent-mode electromagnetic wave cavity resonators, wherein at least a statically-defined magnitude of a gap distance between the distal surface of each post top and the cavity ceiling is defined by the dielectric spacers.

Abstract: Tunable MEMS resonators having adjustable resonance frequency and capable of handling large signals are described. In one exemplary design, a tunable MEMS resonator includes (i) a first part having a cavity and a post and (ii) a second part mated to the first part and including a movable plate located under the post. Each part may be covered with a metal layer on the surface facing the other part. The movable plate may be mechanically moved by a DC voltage to vary the resonance frequency of the MEMS resonator. The cavity may have a rectangular or circular shape and may be empty or filled with a dielectric material. The post may be positioned in the middle of the cavity. The movable plate may be attached to the second part (i) via an anchor and operated as a cantilever or (ii) via two anchors and operated as a bridge.

Abstract: An RF cavity filter is disclosed. The disclosed filter includes: a housing having at least one cavity defined; a cover coupled to an upper portion of the housing; at least one resonator contained within the at least one cavity; at least one hole formed in the cover; at least one grounding bolt configured to be inserted into the hole, having a screw thread formed on a part of an outer perimeter, and having a center hole in a center portion; and at least one tuning bolt inserted into the housing through the center hole along a screw thread formed on an inner perimeter of the center hole, where the grounding bolt has a flange part formed on a lower portion that is in contact with the tuning bolt and a lower portion of the cover.

Abstract: A radio frequency (RF) filter includes an input port configured to receive a signal, an output port configured to output a signal, and a tuning probe configured to be movable within a tuning probe port to adjust filter characteristics. The tuning probe port is configured to receive the tuning probe therein, and a locking mechanism is configured to lock the tuning probe in the tuning probe port at a desired depth and further configured to prevent movement of the tuning probe in the tuning probe port when the locking mechanism is in a locked configuration.

Abstract: A microwave resonant cavity is provided. The microwave resonant cavity includes: a sidewall having a generally cylindrical hollow shape; a gas flow tube disposed inside the sidewall and having a longitudinal axis substantially parallel to a longitudinal axis of the sidewall; a plurality of microwave waveguides, each microwave waveguide having a longitudinal axis substantially perpendicular to the longitudinal axis of the sidewall and having a distal end secured to the sidewall and aligned with a corresponding one of a plurality of holes formed on the sidewall; a top plate secured to one end of the sidewall; and a sliding short circuit. The sliding circuit includes: a disk slidably mounted between the sidewall and the gas flow tube; and at least one bar disposed inside the sidewall and arranged parallel to the longitudinal axis of the sidewall.

Abstract: A recess waveguide microwave chemical plant for production of ethene from natural gas and a process for production of ethene using the plant. The plant includes a recess waveguide, a mode transducer and coupling orifice plate, an adjustable short-circuiting plunger, and a chemical reactor; wherein with the recess waveguide as a main body, the mode transducer and coupling orifice plate is at the left side of the recess waveguide, the adjustable short-circuiting plunger is at the right side of the recess waveguide, and the chemical reactor is across the recess waveguide.

Abstract: The invention relates to a cavity filter comprising at least one tuning conductor (3) presenting a hollow portion (4), an isolation device (6) for a tuning conductor (3) of a cavity filter, and a node in a mobile communications network, comprising a cavity filter. According to the invention, the tuning conductor (3) comprises an isolation device (6) in a non-conductive material, which isolation device (6) is at least partly inserted into the hollow portion (4), and an insertion element (7) in a conductive material presenting a male thread (7a) that is engaged with an inner surface of the isolation device (6).

Abstract: A cavity filter defines a cavity with an opening on a top portion thereof and includes a lid to cover the opening of the cavity. A plurality of resonators are secured on a bottom portion opposite to the top portion of the cavity. The lid includes a plurality of bases extending from the lid toward the plurality of the resonators, respectively. A plurality of threaded holes penetrating the lid and one of the bases faces to the plurality of resonators, respectively. Each threaded hole includes a stopper portion extending from an inner surface of the threaded hole inward to form a step defining a hole in communication with the threaded hole. Each threaded hole corresponds to a tuning post to adjust a resonating frequency of the cavity filter.

Abstract: Various exemplary embodiments relate to a tuning element assembly and method for tuning an a radio frequency (RF) component, where the component has one or more walls defining a cavity, with at least one wall having at least one bore hole. A bushing is mounted in the bore hole in the wall, and a tuning element is slidably mounted and received in the bushing so that the tuning element projects inwardly through the bushing and into the cavity and is axially adjustable. A method of tuning an RF component also includes providing a bushing mounted in a bore in a wall of the RF component, sliding a tuning element that is slidably mounted and received in the bushing so that the tuning element projects inwardly through the bushing and into the cavity by a distance varying according to the sliding of the tuning element, monitoring a performance characteristic of the RF component, and releasing the tuning element so that a desired performance characteristic is achieved.

Abstract: A method and apparatus is described comprising of a plurality of electromagnetic resonant structures coupled to a common process or reaction volume, such that resonance of each structure is maintained while the process or reaction volume is a part of each resonant structure. At the same time, each resonant structure is matched to its respective electromagnetic generator. Such a system allows each generator and its delivery system to run at rated power, with summation of all the powers occurring in the common process or reaction volume. In various embodiments of this invention, the various electromagnetic generators can run at the same or different frequencies. The various resonant structures can be single mode or multimode, or a mixture of single mode and multi mode. The various resonant structures can be arranged spatially in order to couple several structures to the process or reaction volume.

Abstract: An electrical device that comprises a tunable cavity filter that includes a container and a post. The container encloses a cavity therein, wherein interior surfaces of the container are covered with a metal layer. The post is configured be movable through an opening in the container such that at least a portion of the post is locatable inside of the cavity.

Abstract: A planar transformer includes first and second windings that may be comprised of electrically conductive traces etched onto one or more printed circuit boards. The printed circuit boards may be arranged in various orientations so as to change the turns ratio of the planar transformer. In one embodiment, the printed circuit boards are substantially similar and may be electrically connected via connectors that separate the circuit boards. Insulating sleeves may be inserted between the printed circuit boards in an interleaved configuration.

Abstract: A resonator system is presented that has first and second cavity resonators for use in an RF amplifying system employing an RF amplifier device having an output circuit and an RF signal broadcasting antenna coupled to the output circuit. The resonators are interposed between the amplifying device output terminal and the antenna. The first resonator is comprised of a transmission line being a length of two coaxial conductors and tuned to the 3rd harmonic of the operating frequency (3fo). Each resonator has first and second opposing ends with the first end being an open end and the second end being a shorted end. The open end of the first resonator is connected to the output terminal of the RF amplifying device. The second resonator is connected in series with the first resonator and is tuned to the fundamental operating frequency (fo).

Abstract: A linear actuator includes a drive arm and an extension arm each extending along a common drive axis. One of the arms has a plurality of resiliently deformable fingers extending beyond the end of the arm towards the other arm. At least one of the fingers has a thread on its inner face while the other arm has a threaded portion. At least part of the threaded portion is received between the fingers. The fingers are adapted to urge the threads of the two arms into interengagement such that rotation of the drive arm about the drive axis displaces the extension arm along the drive axis. The two threads are arranged such that when the ridge of one thread is received in the groove of the other thread the two sides of the ridge abut the two edges of the mouth of the groove.

Abstract: Various exemplary embodiments relate to a tuning element assembly and method for tuning an a radio frequency (RF) component, where the component has one or more walls defining a cavity, with at least one wall having at least one bore hole. A bushing is mounted in the bore hole in the wall, and a tuning element is slidably mounted and received in the bushing so that the tuning element projects inwardly through the bushing and into the cavity and is axially adjustable. A method of tuning an RF component also includes providing a bushing mounted in a bore in a wall of the RF component, sliding a tuning element that is slidably mounted and received in the bushing so that the tuning element projects inwardly through the bushing and into the cavity by a distance varying according to the sliding of the tuning element, monitoring a performance characteristic of the RF component, and releasing the tuning element so that a desired performance characteristic is achieved.

Abstract: A method for fabrication of a filter includes forming an input transformer pole in a first substrate by forming a first conductive via, forming an output transformer pole in the first substrate by forming a second conductive via, forming one or more filter poles in the first substrate between the input transformer pole and the output transformer pole by forming one or more conductive vias in the first substrate between the input transformer pole and the output transformer pole, fabricating one or more tuning elements on a second substrate, wherein the number of tuning elements corresponds to the number of filter poles between the input transformer pole and the output transformer pole, and bonding the second substrate to a top surface of the first substrate so that each tuning element on the second substrate is aligned with and overlays a filter pole on the first substrate.

Abstract: A TEM mode resonator includes a tuneable cavity defined by an electrically conducting cavity wall. The cavity wall includes a grounding face, a capacitor face and a surrounding wall extending therebetween. An electrically conducting resonator member is disposed within the cavity and extends from the grounding face part way towards the capacitor face. A portion of the resonator member proximate to the capacitor face includes a recess defining an aperture. A tuning mechanism disposed outside the tuneable cavity, includes a tuning arm extending into the tuneable cavity through the aperture. The tuning mechanism is adapted to displace the tuning arm towards and away from the capacitor face. At least a portion of the tuning arm disposed within the cavity is the tuning element, which is formed of either a metal or a dielectric.

Abstract: A radio frequency filter comprising: housing body having input/output connectors and containing space which is divided into spaces by means of diaphragm; at least one resonator rod arranged in the housing; housing cover coupled to the housing body; wherein the housing body and the housing cover are coupled to each other by laser welding. The radio frequency filter according to the present invention can reduce PIMD due to reduce Contact Nonlinearity, and inhibit to erode away because the laser welding method dissolve different metallic materials each other and take a convalent bond, and reduce its manufacturing process time and cost because it is unnecessary drilling a hole and fastening a screw to fasten the housing and the housing cover each other and can simplify its manufacturing process and raise productivity because only irradiate laser beam on irradiated area of the housing cover.

Abstract: The system for the automatically tuning of multicavity filters of high frequency signals, by means of screws sticking out from the lid of the plate incorporating said cavities, comprises a robotized movement imparting subsystem SUB-1A, a measuring subsystem SUB-2M for the extraction of the transfer characteristic, a subsystem SUB-3C to compare said measured values to reference parameters, a subsystem SUB-4G for the generation of said reference parameters, and a subsystem SUB-5CO enslaved to said SUB-4G and SUB-1.

Abstract: One inventive aspect relates to a reconfigurable cavity resonator. The resonator comprises a cavity delimited by metallic walls. The resonator further comprises a coupling device for coupling an electromagnetic wave into the cavity. The resonator further comprises a tuning element for tuning a resonance frequency at which the electromagnetic wave resonates in the cavity. The tuning element comprises one or more movable micro-electromechanical elements with an associated actuation element located in their vicinity for actuating each of them between an up state and a down state. The movable micro-electromechanical elements at least partially have a conductive surface and are mounted within the cavity.

Abstract: A tuning assembly for a radio frequency is disclosed. The tuning assembly includes: a tuning screw grasping unit integrally formed with a main body of the filter, which includes a tuning screw receiving unit and a fastening member for grasping a tuning screw; and a tuning screw inserted into the filter through the tuning screw receiving unit, wherein the filter is finely tuned by inserting the tuning screw into the filter through the tuning screw receiving unit and a female screw unit formed at the filter.

Abstract: The invention refers to a system and method to tune a multicavity filter of microwave signals, said filter comprising a filter body (CF), a removable lid (CO), n resonant cavities dug out in said filter body (CF) and n tuners (TU) susceptible of displacement under the action of movement means. Typically a sub-system to absorb the oscillations and vibrations generated in such displacements is associated to each tuner.

Abstract: A variable radio frequency band filter capable of varying the resonance frequency band comprises a housing having a support; a number of resonator rods arranged along the longitudinal direction of the housing; at least one tuning rod positioned on top of the resonator rods; a tuning support extending through the respective tuning rods along the longitudinal direction of the housing and adapted to slide on top of the respective resonator rods to vary the position of the tuning rods; and a frequency variation unit positioned on a lateral surface of the housing. The frequency variation unit being coupled to an end of the tuning support and adapted to vary the position of the tuning rods, as the tuning support is slid, according to the frequency band.

Abstract: An interface that provides minimum changes in contact pressure over a thermal range is disclosed. The interface is a mated joint of given material, typically metallic, joined by a mechanical fastener or fasteners. The fastener(s) create contact pressure at the joint surface wherein the contact pressure variation over a temperature range is minimized by the use of a thermal compensator having a predetermined length. The thermal compensator's length is chosen by setting the thermally induced expansion delta to offset an equal delta created by the fastener and interface configuration. The difference in expansion of the mated joint and fastener is canceled by the equal, but negative, difference between compensator and fastener. This cancellation of expansion minimizes the change in contact pressure at the joint interface. Maintaining a constant pressure provides PIM reliability during temperature changes.

Abstract: The present invention relates to an improved tuning arrangement to linearise the sensitivity to frequency changes within a certain frequency range in response to tuner displacements relative to a resonator body. The tuning arrangement comprises a tuner and/or resonator having a non-uniform distribution of the effective dielectric permittivity along the axis of tuner displacement. The non-uniform distribution of the effective dielectric permittivity is realised by subdividing the tuner into an arbitrary number of sections, each of which distinguishable at least by their geometrical shape and the value and distribution of the dielectric coefficient ?r.

Abstract: Oven enclosure with microwave functionality, in which, at a short distance from an enclosure bottom panel, support elements are provided for accommodating a microwave-permeable base plate serving as a food holder.

Abstract: The present invention relates to a tuning screw assembly comprising a sleeve (100) with internal threads for engaging a tuning screw (200) having external threads. The sleeve comprises a first threaded portion (32) which is axially displaced in relation to a second threaded portion (34) for frictionally locking said screw body in said sleeve. The invention also relates to a method of manufacturing said friction locking sleeve and to a resonator comprising said friction locking sleeve.

Abstract: A variable radio frequency band filter capable of varying the resonance frequency band comprises a housing having a support; a number of resonator rods arranged along the longitudinal direction of the housing; at least one tuning rod positioned on top of the resonator rods; a tuning support extending through the respective tuning rods along the longitudinal direction of the housing and adapted to slide on top of the respective resonator rods to vary the position of the tuning rods; and a frequency variation unit positioned on a lateral surface of the housing. The frequency variation unit being coupled to an end of the tuning support and adapted to vary the position of the tuning rods, as the tuning support is slid, according to the frequency band.

Abstract: A microstrip-based RF coil for use in an MRI apparatus constructed to perform human head imaging is provided and includes (a) a cylindrical non-magnetic core module having an outer surface and a longitudinal axis, a cylindrical bore extending through the core module along the longitudinal axis and defining an inner surface; and a plurality of conductive strip lines. The strip lines extend parallel to the longitudinal axis on the outer surface of the core module. The coil is constructed such that one or more of the conductive strips are divided into conductive microstrip segments with one or more tuning capacitors being bridged between two adjacent microstrip segmented sections of the conductive strip. The coil also include a shield support cylinder that is disposed concentrically about the core module and is spaced therefrom to receive the tuning capacitors.

Abstract: An RF cavity resonator (400) that includes: a resonator chamber (410) for containing an RF field; an RF coupling element (450, 452) coupled to the resonator chamber for introducing the RF field into and extracting the RF field from the resonator chamber; a tuning assembly (420) for causing the RF field to resonate at a desired frequency, wherein at least a portion of the tuning assembly is coupled within the resonator chamber; and a heat transport element (440) for transporting heat from the RF cavity resonator, wherein at least a portion of the heat transport element is coupled within the resonator chamber, the heat transport element including a phase change material, a housing for enclosing the phase change material, means for circulating the phase change material within the housing, and an electrically conductive surface for isolating the phase change material from the RF field.

Abstract: A system and method for a plunger assembly includes a tuning slug with a bore in the stem, a tuning screw rotatably disposed in the stem, and a coupling assembly to rotatably secure the tuning screw to the slug. The system and method may also include a locking assembly to secure the postion of the assembly.

Abstract: Disclosed is a method and apparatus for tuning a microwave apparatus. The chamber volume of the microwave apparatus can be changed by moving a flexible portion of a flexible wall while a perimeter portion of the flexible wall remains fixed.

Abstract: A system and method for a plunger assembly includes a tuning slug with a bore in the stem, a tuning screw rotatably disposed in the stem, and a coupling assembly to rotatably secure the tuning screw to the slug. The system and method may also include a locking assembly to secure the postion of the assembly.

Abstract: A microwave applicator for heating loads being a waveguide transition between the rectangular TE10 and TE20 modes comprising a TE10 mode section and a TE20 mode section. The location of the load being inside said TE20 mode section and with its major axis perpendicularly to the major propagation direction of the TE20 mode, close to a shorting wall of said TE20 mode section and also close to the centreline of said propagation direction.

Abstract: The dielectric loaded cavity for high frequency filters consists of a metal container housing s dielectric block held in position by supporting plates, that also sustains coupling and tuning elements. This invention provides broadband filters, small in size and with low losses. Its high symmetry structure considerably reduces the energizing of spurious modes and furthermore facilitates the design using automatic calculation procedures, on the basis of accurate electromagnetic models.

Abstract: First and second electrically conductive rods are provided inside a shielded electromagnetic test chamber. These rods are energized to radiate electromagnetic energy inside the chamber. The rods are mounted inside the chamber at right angles to one another, the first rod is movable through the interior volume in a first direction perpendicular to its long axis, and the second rod is movable through the chamber in a second direction perpendicular both to its own long axis and to the first rod's direction of motion. Energy is supplied to the two rods in a way that enhances the uniformity of the electromagnetic field applied to a working volume inside the chamber as the two rods move through the chamber.

Abstract: A method for tuning a cavity filter is provided. The cavity filter includes a plurality of tuning members. The method includes selecting a stored set of positional values for the tuning members, driving the tuning members of the cavity filter to the stored set of positional values, and further adjusting the position of the tuning members as necessary to achieve a desired frequency response for the cavity filter.

Abstract: A tuner (10) for a reverberation chamber is provided comprising a plurality of electrically conductive surfaces (12) attached to each other in a Z-fold configuration. Each lateral edge (15) of the tuner is contacted with a generally planar, laterally positioned substrate (16) which prevents lateral extension or medial compression of the Z-fold. Optionally, end substrates (18) are attached to each of the two leading edges (17). Also, a device minimizes electromagnetic radiation leakage along a shaft including: a bearing housing; a plurality of thrust bearings contacting the bearing housing and axially juxtaposed along the shaft so that at least two thrust bearings oppose each other; a radial bearing intermediate each thrust bearing; and a provision for adjustably moving the thrust bearings toward each other so as to compress the thrust bearings against the bearing housing.