Abstract: A multiple carrier adaptive notch filter (ANF) module selectively filters a received wideband communication signal to eliminate narrowband interference that lies within the frequency spectrum of the wideband communication signal. To determine the presence of narrowband interference, the multiple carrier ANF module scans various known narrowband channels that lie within the frequency spectrum of the wideband communication signal and determines signal strengths for each of the narrowband channels. The signal strengths from the narrowband channels are compared to a threshold that is derived from a statistical combination of the narrowband signal strengths. Narrowband channels having signal strengths that are greater than the threshold are determined to have interference.

Abstract: A system having a transmit path and a receive path coupled to an antenna includes a cryostat, a receive filter disposed in the cryostat, a transmit filter disposed outside of the cryostat and in the transmit path, and a coupler that couples the antenna and the receive filter. The coupler includes a phase-adjusting portion disposed in the cryostat to provide duplexing functionality. The receive path includes the filter and the phase-adjusting portion of the coupler.

Abstract: An RF receiver includes first and second RF filter stages and an amplifier stage. An output terminal of the first RF filter stage is coupled to an input terminal of the amplifier stage, and an output terminal of the amplifier stage is coupled to an input terminal of the second RF filter stage. The first and second RF filter stages are not identical, inasmuch as, for instance, the first and second RF filter stages may provide different selectivities. The first RF filter stage may include a low loss RF filter to establish a low noise figure for the RF receiver. The isolation provided by the amplifier stage permits the first and second RF filter stages to include high-order RF filters or, alternatively, multiple low order RF filters.

Abstract: A dual operation mode all temperature filter is provided. The dual operation mode filter is provided with a housing defining at least two cavities, an input port and an output port. It is also provided with a non-superconducting resonator disposed in a first one of the cavities and a superconducting resonator disposed in a second one of the cavities. The second resonator comprises a superconducting material containing 8-15% silver. The dual operation mode filter filters at a relatively high level at temperatures below a threshold temperature and at a lower, conventional level, at temperatures below the threshold.

Abstract: An electromagnetic resonator has a resonant element made of a high-temperature superconducting material such as YBa2Cu3O7-x. The resonant element has a substrate coated with a thermally conductive layer such as silver, over which the high-temperature superconductor material is placed. The thermally conductive layer distributes heat along the length of the resonant element to minimize the effects of localized heating at, for instance, the center of the resonator. The resonant element is held to a housing by a mounting mechanism including a post made of polycrystalline alumina. The polycrystalline alumina transfers heat away from the center of the resonant element and may be used to suppress spurious response due to second harmonic resonance.

Abstract: An electromagnetic resonator has a resonant element made of a high-temperature superconducting material such as YBa2Cu3O7-x. The resonant element has a substrate coated with a thermally conductive layer such as silver, over which the high-temperature superconductor material is placed. The thermally conductive layer distributes heat along the length of the resonant element to minimize the effects of localized heating at, for instance, the center of the resonator. The resonant element is held to a housing by a mounting mechanism including a post made of polycrystalline alumina. The polycrystalline alumina transfers heat away from the center of the resonant element and may be used to suppress spurious response due to second harmonic resonance.

Abstract: An electromagnetic resonator has a resonant element made of a high-temperature superconducting material such as YBa2Cu3O7−x. The resonant element has a substrate coated with a thermally conductive layer such as silver, over which the high-temperature superconductor material is placed. The thermally conductive layer distributes heat along the length of the resonant element to minimize the effects of localized heating at, for instance, the center of the resonator. The resonant element is held to a housing by a mounting mechanism including a post made of polycrystalline alumina. The polycrystalline alumina transfers heat away from the center of the resonant element and may be used to suppress spurious response due to second harmonic resonance.

Abstract: An electromagnetic filter includes a filter housing containing a first resonant cavity and a second resonant cavity. Resonators are disposed within each of the cavities. The electromagnetic filter also includes a cavity wall separating the first resonant cavity and the second resonant cavity. The cavity wall includes a T-shaped aperture to achieve magnetic coupling between the first resonant cavity and the second resonant cavity.

Abstract: A method of producing ceramic superconducting materials such as YBa.sub.2 Cu.sub.3 O.sub.x includes blending together starting materials for the superconducting material. The blend of starting materials are formed into a layer and sintered at a temperature above the peritectic temperature for the superconducting material. Prior to sintering, the starting materials for the superconducting material may be unreacted. The starting materials may also be partially reacted prior to sintering by calcining for a period of time at a temperature which does not result in full reaction of the starting materials to the chemical composition of the desired superconducting material.

Abstract: A resonant structure has a center conductor, a dielectric element, and an outer conductor. The center conductor is a substrate with a coating of a superconductor on its outer surface, and the outer conductor is a substrate with a coating of a superconductor on its inner surface. The dielectric element has a passageway which is sized for receiving the inner conductor so that there is substantially complete contact between the layers of superconductor coating and the dielectric. Similarly, the outer surface of the dielectric element is sized to match the inner superconductor coated surface of the outer conductor.

Abstract: A stripline resonator has a center conductor between layers of dielectric which are, in turn, between ground planes. The center conductor is made of a high-temperature superconducting material, preferably having a total superconductor thickness from at least about one micron to at least about one-hundred microns. The superconducting material has an electromagnetic penetration depth and the ratio of the thickness of the superconductor to the penetration depth is from at least about 4:1 to at least about 100:1. The center conductor may be formed of a substrate coated with the high-temperature superconducting material so that the center conductor is discrete from the dielectric element. The center conductor may have a length which is greater than the length of the dielectric element.

Abstract: An electromagnetic device, such as a resonator for a filter, incorporates a high-purity polycrystalline alumina. The device may include a superconducting component, which must be cooled significantly below room temperature. The high-purity polycrystalline alumina may be a dielectric slab in a stripline resonator, or may be used as a stand for holding other components. The high-purity polycrystalline alumina exhibits a very low loss tangent at cryogenic temperatures, and therefore will result in an electromagnetic device with superior performance characteristics.

Abstract: A cryostat includes an upper shell and a lower shell connected along a seam. The shells are made of a relatively thin material which would be subject to collapse once the cryostat is evacuated. In order to resist collapsing forces, a brace is placed inside the cryostat between opposing walls of the shells. The brace has a connecter which includes a pin and post that has an opening for receiving the pin. The connectors allow easy assembly and disassembly of the cryostat while still resisting compressive forces.

Abstract: A bandstop filter contains one or more resonant circuits connected by interconnecting transmission lines. The resonant circuits each have a transmission line connected between two capacitors. One capacitor is connected to the interconnecting transmission line and the other capacitor is connected to ground. The resonant circuits may have a helical coil of superconducting materials as the transmission line. The capacitors may be in the form of screws, which can be inserted into or removed from the center of the helix. The helix may be formed as a discrete structure and supported by a low-loss material within a housing.

Abstract: A resonator mounting mechanism includes a stand having a groove in the head of the stand. A cap, which also has a groove, fits over the top of the stand to hold a resonator in place. The stand has two slots formed between lugs, which receive arms on the cap. The sidewalls of the lugs forming the slots and the arms on the cap are tapered so that there is an interference fit between the cap and the stand. The interference fit between the slots and arms holds the cap, stand, and resonator in a fixed position. The bottom of the stand includes structure for attaching the stand to a wall of a resonator cavity, or the like.

Abstract: A coating device for use in coating circular cross-sectioned substrates has a semi-circular doctor blade. The coater may also have a plate for holding axially symmetric substrates which can be rotated about an axis. A groove in the plate centers the substrate on the plate for rotation. The doctor blade is located adjacent to the substrate such that when the plate and substrate are rotated, the doctor blade applies a uniform thickness of coating to one side of the substrate. After one side of the substrate has been coated, the other side is coated by placing the substrate coated side down on a plate with a larger groove to accommodate the increased size of the substrate due to coating.

Abstract: A tuner including a shaft extendible through an aperture extending completely through a jacket of the tuner. The tuner includes a shaft tensioning and grounding structure and a tuning material holder comprising a cup-shaped structure with a clasping element.

Abstract: A method of manufacture of a textured layer of a high temperature superconductor on a substrate. The method involves providing an untextured high temperature superconductor material having a characteristic ambient pressure peritectic melting point, heating the superconductor to a temperature below the peritectic temperature, establishing a reduced pO.sub.2 atmosphere below ambient pressure causing reduction of the peritectic melting point to a reduced temperature which causes melting from an exposed surface of the superconductor and raising pressure of the reduced pO.sub.2 atmosphere to cause solidification of the molten superconductor in a textured surface layer.

Abstract: A mechanical coupling device for selectively connecting and disconnecting an apparatus to a thermal source. The coupling device includes a thermal bridge element comprised of a flexible structure having a first coefficient of thermal expansion, and a thermal stress element disposed about the thermal bridge element with the thermal stress element having a second coefficient of thermal expansion. The difference in coefficients of thermal expansion act to cause stressing of the thermal bridge element into thermal contact with the apparatus.

Abstract: A resonant structure and filter include a resonant element mounted to the cover of a housing. A transmission line passes through the cover and is connected to a coupling loop. The coupling loop is located adjacent the resonator and is connected to ground. A coupling tuner is attached to the housing and includes a post which is movably attached to the housing. The tuner extends between the coupling loop and the resonator, and may be adjusted to change the electromagnetic coupling.