Abstract: A circulator comprises first and second couplers. The first and second couplers are coupled by first and second transmission lines. First and second magnetic fields are provided crossing the first and second transmission lines, respectively. In an exemplary embodiment, the magnetic fields are substantially parallel with and within a plane defined by the first and second transmission lines.

Abstract: A method for detecting entry into a secure area uses a passive entry detector. The secure area has an access door, having a closed position. The passive entry detector comprises a source of energy internal or external to the passive entry detector, an activator for detecting a change in the access door from its closed position, and for releasing the energy in response to the change of the access door from the closed position. The energy is transferred to one or more pseudo random units. Each of the pseudo random units has a plurality of mechanical states. The pseudo random units are responsive to the activator. The activator induces a change of the mechanical states in the pseudo random units upon transfer of energy. The pseudo random units report the mechanical states upon interrogation. Using above passive entry detector, a first interrogation using the interface is performed to create a first record to identify one or more mechanical states with the access door in the closed position.

Abstract: A millimeter wave (MMW) antenna array includes a continuous transverse stub (CTS) radiating aperture comprising a set of spaced continuous transverse stubs, each having a longitudinal extent. A series feed system is coupled to an excitation source for exciting the stubs with MMW electromagnetic energy having a linear phase progression along the longitudinal extent of the stubs to produce an array beam which can be scanned over a beam scan range by changing the excitation frequency.

Abstract: A foldable radiator assembly includes a flexible dielectric substrate structure having a radiator conductor pattern formed therein. The flexible substrate structure can be flexible for movement between a folded position and a deployed position, or can be fixed in position by dielectric structures. An excitation circuit excites the radiator conductor pattern with RF energy. Strips of the radiator assemblies can be used to form an array aperture.

Abstract: A miniaturized microwave circuit. The novel circuit includes a first substrate, a first ground plate disposed on a bottom surface of the first substrate, a second substrate attached to a top surface of the first substrate and adapted to cover a portion of the first substrate, a second ground plate disposed on a top surface of the second substrate, a pattern of metallization disposed between the first and second substrates to form a stripline circuit, one or more ground paths disposed on the top surface of the first substrate and including a plurality of vias connected to the first ground plate, and one or more openings cut into the second substrate and second ground plate, wherein each opening follows and is aligned over a portion of a ground path and is filled in with conducting material, such that the second ground plate is connected to the first ground plate.

Abstract: A method and apparatus for fault management in a network. A network architecture is disclosed including at least one network switch, several network interface cards, several processors (host) and a network manager. Fault reporting and detection logic is implemented in each switch and in each network interface card. In addition, multiple fault reporting pathways are provided for each switch and each network interface card. As a result, utilizing message exchanges such as Fibre Channel exchange messages, the switch, the network interface cards and the processors (host) are able to autonomously generate and report faults to the network manager. The combined fault reporting enables the network manager to more accurately isolate faults. In addition, because of the autonomous nature of the fault reporting, faults may be detected and corrected prior to the initiation of a communication session.

Abstract: A Synthetic Aperture Radar (SAR) avoids the need for an INS/GPS by focusing a SAR image having discernible features and a center. The image is formed from digitized returns, each of the digitized returns having a phase and an amplitude. The focusing steps of an algorithm processing the digitized returns include: computing a coarse range and coarse range rate of the center of the image, motion compensating the digitized returns, converting the digitized returns in polar format into an orthogonal Cartesian coordinate system, autofocusing the image data to obtain a focused image, performing a Fourier transform to obtain a focused image described by the returns, computing an estimated fine range and fine range rate from features contained within the focused image, and converging the fine range and fine range rate within the orthogonal Cartesian coordinate system for use within the azimuth and range coordinate system and motion compensating the digitized returns.

Abstract: A stream computer comprises a plurality of interconnected functional units. The functional units are responsive to a data- stream containing data and tokens. The data is to be operated on by one or more of the plurality of interconnected functional units. Digital logic cooperatively associated with one of the functional units adds one or more tokens to the data stream presented to one of the functional units. The tokens are representative of the type of data being generated or received by the functional units. The digital logic also reports the occurrence of said one or more tokens within said data stream without interrupting the data stream. The digital logic reports one or more tokens arriving at one of the functional units as part of the data stream to a graphical programming environment. The graphical programming environment is compatible with human perception.

Abstract: A heat exchanger apparatus including a two-dimensional array of heat exchanging conduits, wherein each conduit includes an inlet and an outlet, and a manifold for providing heat exchanging fluid to the inputs of the heat exchanging conduits and for receiving heat exchanging fluid from the outputs of the heat exchanging conduits.

Abstract: A delta-sigma modulator. The novel delta-sigma modulator includes one or more filter stages arranged in cascade, wherein each filter stage includes a first circuit for generating a first output signal and second circuit for generating a second output signal; and a summing circuit for adding the first and second output signals from each of the filter stages. In an illustrative embodiment, the first circuit is a bandpass filter including an inductive-capacitive resonator and the second circuit is an integrator, which generates a second output signal that is orthogonal to the first output signal. The output of the summing circuit is digitized and then converted back to analog to provide a feedback signal. The feedback signal is subtracted from an input signal, and the resultant difference signal is input to a first filter stage.

Abstract: A multilayer switching assembly for switching high frequency signals has MEMS structures on a ceramic substrate having a top surface 500, a bottom surface and a plurality of insulating layers (510,512,514). The insulating layers are separated by at least a first conductor 502 and a second conductor 504. The first conductor 502 is connected to a ground potential. The second conductor 504 is separated from the first conductor 502 by one of the insulating layers. The second conductor presents a specific impedance (50 ohms) with respect to the first conductor to high frequency signals traveling on the second conductor. 64 MEMS structures (e.g. 540,708,716,718, 720) are mounted on the top surface. Each MEMS has an input, an output, and a control. The input connected to the second conductor. The output is connected to a coplanar waveguide (508) placed on the top surface (500). The control is connected to the bottom surface.

Abstract: SAR images are improved by a method for acquiring a synthetic aperture image from a sequence of periodic pulse returns where the sequence of periodic pulse returns is interspersed with interrupts, i.e. missing pulses. The interrupts mark the start and end of one or more segments, where the segments contain the periodic pulse returns form the SAR image. The method comprises the steps of: converting said pulse returns into a digital stream; performing an azimuth deskew on said digital stream to obtain a deskewed digital stream; forming a forward-backward data matrix from the deskewed digital stream for one or more segments; forming an average segment covariance from the forward-backward data matrix; computing a model order for the average segment covariance; computing one or more linear prediction coefficients using data contained in the forward backward data matrix, and model order; using the linear prediction coefficients to compute missing pulse returns belonging within the interrupts.

Abstract: Target detection in the presence of non stationary clutter is improved by a radar receiver on a moving platform for detecting a target using a plurality of short coherent arrays and a plurality of long coherent arrays synthesized from the short coherent arrays overlapping the target. The target is obscured by slow scale clutter and fast scale clutter in the vicinity of the target.

Abstract: A transverse device array phase shifter includes an overmoded waveguide structure having a top conductive broad wall surface, a bottom conductive broad wall surface and opposed first and second conductive side wall surfaces. At least one transverse device array circuit is positioned in the waveguide circuit. Each circuit comprises a generally planar dielectric substrate having a microwave circuit defined thereon, and a plurality of spaced discrete phase shifter elements. The substrate is disposed within the waveguide structure generally transverse to the side wall surfaces. A bias circuit applies a voltage to reverse bias the phase shifter elements. The transverse device array phase shifter circuit causes a change in phase of microwave or millimeter-wave energy propagating through the waveguide structure.

Abstract: A miniaturized, circularly polarized SDS patch antenna. Generally, the inventive antenna includes a ground plane over which a first patch is disposed. A short is provided between a first edge of the first patch and ground plane. A second patch is disposed over said first patch. A second short is provided between a first edge of the second patch and the first patch. The patch antenna of the illustrative embodiment further includes a first volume of dielectric disposed between the ground plane and the first patch. A second volume of dielectric is disposed between the first patch and the second patch. In the illustrative embodiment, the edges are shorted orthogonally. In an alternative embodiment, the shorted edges are in substantially parallel alignment. In yet another alternative embodiment, the antenna is designed for dual frequency operation. In the best mode, the area of the first patch is greater than the area of the second patch.

Abstract: An RF signal transition includes a channelized microstrip transmission structure, and a coplanar wave guide structure in electrical communication with the channelized microstrip transmission structure. A caged troughline transition structure is in electrical communication with the coplanar wave guide structure. A caged coaxial transmission structure is in electrical communication with the troughline transition structure. The signal transition may be embedded in a flexible printed wiring board structure with a circulator for a conformal antenna structure.

Abstract: Motion compensation for coherent combination of pulses facilitates a SAR image of a scene on earth's surface. A great circle (406) is centered with respect to the earth's center, The great circle (406) has an axis (412) perpendicular to a first plane. Axis (412) passes through the earth's center. The first plane contains great circle (406) and includes the earth's center. Great circle (406) has a first center defined by an intersection of the first plane and axis (412). The scene has one or more radar scatterers and is located on a surface (402). The radar system is mounted on a moving platform (400) moving with a component of motion in a direction along great circle (406). The radar comprises a radar receiver for digitizing the radar returns having a phase from scatterers on surface (402), and a computer for focusing the phase of said radar returns from the scatterers on surface (402).

Abstract: A digital signal-rate converting system. The system includes a first mechanism for receiving a digital input signal characterized by a first rate. A second mechanism interleaves the digital input signal in accordance with a predetermined pattern to yield an adjusted-rate digital signal. The adjusted-rate digital signal is representative of the digital input signal, such as a bandpass signal. In a more specific embodiment, the digital signal-rate converting system is an input interface of a rate-converting Digital-to-Analog Converter (DAC). The rate-converting DAC includes a DAC module, such as multi-bit or a 1-bit DAC module, for receiving the adjusted-rate digital signal and providing an analog output signal with a desired bandwidth or center frequency in response thereto. In the specific embodiment, the adjusted-rate digital signal approximates the digital input signal and is characterized by a rate based on a desired center frequency of the analog output signal.

Abstract: A beamforming system and method. The inventive beamforming system is adapted for use with an array antenna having a plurality of antenna elements and includes a Fast Fourier Transform (EFT) for transforming a signal received by an antenna into a plurality of frequency subbands. A plurality of adaptive processors are included for performing adaptive array processing on each of the subbands and providing a plurality of adaptively processed subbands in response thereto. A normalizing processor is also included for normalizing the adaptively processed subbands. In the illustrative embodiment, the signal is a Global Positioning System (GPS) signal and a digital multiplier for applying a weight to a respective frequency subband for each of the elements of the array. The weights are chosen to steer a beam in a direction of a desired signal. Normalization involves adjusting the amplitude of one or more of the subbands to remove any bias distortion due to the adaptive processing thereof.

Abstract: A quantizer adapted for use with a delta-sigma analog-to-digital converter. The quantizer includes first and second comparators adapted to compare an input analog signal to a threshold and provide a digital output in response thereto. First and second thresholds are provided to the first and second comparators respectively. In accordance with the present teachings, a mechanism is provided for changing the thresholds to minimize conversion errors. While the mechanism for changing the thresholds may be implemented with resistive and/or capacitive ladders, in the illustrative embodiment, digital-to-analog converters are utilized. The DACs are driven by error shaping logic. The inventive quantizer allows for an improved delta-sigma analog-to-digital converter design which combines an ADC and a DAC. The DAC reconstructs the analog equivalent of the digital output of the ADC. The ADC is a flash converter consisting of one comparator per threshold.