Abstract: An antenna includes at least two planar conductors cooperatingly arranged in a planar configuration having a bifilar spiral winding structure, a log-periodic structure or a sinuous configuration and a frequency-independent reflective backing situated on one axial side of the planar configuration. The backing includes a solid, disk-shaped dielectric substrate having a relatively high dielectric constant, and three mutually perpendicular arrays of elongated dielectric elements at least partially embedded in the solid dielectric substrate. The elongated dielectric elements have a relatively low dielectric constant. The elongated dielectric elements of the three mutually perpendicular arrays are formed as rods, cones and rings.

Abstract: An Instantaneous Frequency Measurement (IFM) receiver that receives a signal from a target and determines the frequency of the signal. The IFM receiver includes delay lines selected in lengths forming relatively prime ratios or by using the preferred method of the present invention which minimizes the total number of different delays required to achieve a given accuracy in frequency measurement.

Abstract: An antenna includes at least two planar conductors cooperatingly arranged in a planar configuration having a bifilar spiral winding structure, a log-periodic structure or a sinuous configuration and a frequency-independent reflective backing situated on one axial side of the planar configuration. The backing includes a solid, disk-shaped dielectric substrate having a relatively high dielectric constant, and three mutually perpendicular arrays of elongated dielectric elements at least partially embedded in the solid dielectric substrate. The elongated dielectric elements have a relatively low dielectric constant. The elongated dielectric elements of the three mutually perpendicular arrays are formed as rods, cones and rings.

Abstract: An integrated receiver includes an Instantaneous Frequency Measurement (IFM) device, an interferometer and switches. The IFM receives signals from a target and determines the frequency of the signals. The IFM includes the shared N-channel phase receiver. The interferometer also receives the signals from the target and determines the angle-of-arrival (AOA) of the signals. The interferometer includes the shared N-channel phase receiver and shares the shared N-channel phase receiver with the IFM. The switches selectively connect the shared N-channel phase receiver to the IFM when the IFM is determining the frequency of the signals, and selectively connect the shared N-channel phase receiver to the interferometer when the interferometer is determining the AOA of the signals. The shared N-channel phase receiver determines phase information indicative of the frequency of the signals and the AOA of the signals.

Abstract: A detector for detecting radiant energy includes at least one detecting element and a detector readout element. The at least one detecting element substantially absorbs the radiant energy and exhibits a structural change in response thereto. The detector readout element, positioned in non-contacting proximity to the at least one detecting element, is responsive to the structural change of the at least one detecting element. The non-contacting detector readout element provides an indication signal corresponding to the structural change, whereby the corresponding indication signal is representative of the radiant energy detected by the at least one detecting element.

Abstract: A virtual beam system operating in an environment, including a non-compatible receiver, includes a transmitting subsystem and a receiving subsystem. The transmitting subsystem includes an array of transmitting elements and an element position encoded composite signal generator for generating an element position encoded composite signal. The array of transmitting elements is operatively coupled to the signal generator. The transmitting subsystem radiates the element position encoded composite signal via the array of transmitting elements. The receiving subsystem is responsive to the element position encoded composite signal and includes a receiving element and an element position encoded composite signal decoder for decoding the element position encoded composite signal. The receiving element is operatively coupled to the signal decoder.

Abstract: A broadband impedance matching circuit employs active circuits featuring non-Foster reactance behavior, such as negative capacitor circuits and negative inductor circuits, to achieve extremely broadband matching of electrically small antennas. The matching circuit includes at least one non-Foster reactance circuit selected to neutralize the reactance exhibited by the antenna. The circuit further includes a dynamic dispersive impedance transformer circuit which compensates for the frequency dependent radiation resistance presented by the electrically small antenna. The dynamic dispersive impedance transformer is constructed using complementary Foster and non-Foster reactance circuits configured as an impedance transformer.

Abstract: A communication system for transferring data through the air over a relatively short fixed distance comprising a transmitting antenna which comprises a leaky coaxial cable for radiating electromagnetic energy modulated with data to be transferred; and a plurality of non-linear fixed beam array antennas for receiving the modulated electromagnetic energy from the leaky coaxial cable. The plurality of fixed beam array antennas are juxtaposed with the transmitting antenna such that the transmitting antenna extends at least partially through the near-field regions of the plurality of fixed beam array antennas. The communication system also comprises a selection means which determines which radio frequency output from the plurality of non-linear fixed beam array antennas exhibits the greatest radio frequency power and outputs that particular radio frequency output to a receiver.

Abstract: An antenna and system for determining two-dimensional angle-of-arrival includes circular array interferometers for azimuth, linear interferometers for elevation, and a mast for positioning the interferometers in a vertically stacked orientation. The circular array interferometers exhibit azimuth constant-phase-difference contours orthogonal to elevation constant-phase-difference contours exhibited by the linear interferometers. An antenna and system for determining azimuth of input signals includes ambiguous and non-ambiguous circular array interferometers. The non-ambiguous circular array interferometer resolves ambiguities introduced by the ambiguous circular array interferometer, the at least one ambiguous circular array interferometer operatively coupled to a low-order Butler matrix and power divider/combiner such that a high order Butler matrix is not required to generate omnidirectional phase modes from the ambiguous circular array interferometer.

Abstract: An apparatus and method for exciting an antenna with dual frequency bands which comprises feeding a first channel of the antenna with a first signal in the VHF band such that a first current is established in a first direction resulting in a first polarization, feeding a second channel of the antenna with a second signal such that a second current is established in a second direction resulting in a second polarization, and isolating characteristics of the first channel from characteristics of the second channel and the characteristics of the second channel from the characteristics of the first channel such that both the first channel and the second channel are adapted to transmit and receive energy within the same antenna structure without appreciable coupling between the first channel and the second channel.

Abstract: An apparatus and method for exciting an antenna with dual frequency bands which comprises feeding a first channel of the antenna with a first signal in the VHF band such that a first current is established in a first direction resulting in a first polarization, feeding a second channel of the antenna with a second signal such that a second current is established in a second direction resulting in a second polarization, and isolating characteristics of the first channel from characteristics of the second channel and the characteristics of the second channel from the characteristics of the first channel such that both the first channel and the second channel are adapted to transmit and receive energy within the same antenna structure without appreciable coupling between the first channel and the second channel.

Abstract: A satellite based signal transmission and reception system which generates multiple beams with low side lobes and minimal crossover losses. The system includes a focusing device and an array of signal generator elements coupled to feed radiator elements. The feed radiator elements are assigned into overlapping beam sub-arrays characterized by a frequency and radiated beam polarization. Each overlapping sub-array generates a transmission beam signal which is orthogonally polarized with respect to the beam generated by the other overlapping sub-array. The use of beam orthogonality provides for physically overlapping beam sub-arrays without the use of analog combining networks which are inherently lossy structures. This allows beams to be generated having a highly tapered amplitude distribution to simultaneously achieve low side lobe levels and low beam cross over losses.

Abstract: A direct digital synthesizer circuit and method for reducing the harmonic content in a synthesized output signal. The direct digital synthesizer generates first and second address signals driving first and second sine look-up read only memory (sine ROM) circuits. The first and second sine ROMs generate first and second digital sine wave signals which are offset in phase from one another by 180 degrees. The first and second digital sine wave signals are converted to first and second analog sine wave signals. The first and second analog sine wave signals are combined in a subtractor circuit. As a result of the phase relationship between the first and second analog sine wave signals, the fundamental component of these signals are emphasized by subtraction while the second harmonic component of theses signals are simultaneously de-emphasized.

Abstract: A chirp direct digital synthesizer is formed with a phase and frequency tracker circuit to provide both enhanced resolution and reduced power consumption. The phase and frequency tracker circuit operates at a sub-synchronous clock rate and provides periodic phase and frequency correction data to the direct digital synthesizer. The phase and frequency tracker circuit is suitable for both continuous wave and chirp direct digital synthesizer operation.

Abstract: An improved method for use with an open-path fast Fourier infrared spectrometer performs real-time, spectral alignment on measured interferograms to reduce measuremental errors. The improved method includes the step of selecting a plurality of water-vapor lines in a defined spectral region and comparing the centerline of these measured water vapor lines to a reference library. From these comparisons, the spectrometer calculates correction factors to apply to the spectrometer bandwidth. The improved spectrometer performs transform functions on selected segments of the spectrometer bandwidth which introduce integer-continuous corrective shifts on subsequently measured interferogram data.

Abstract: A digitally beam formed phased array antenna capable of both transmitting and receiving signals is constructed from a series of digitally controlled antenna elements. To transmit signals, a series of direct digital synthesizers is used to drive the antenna elements forming the phased array. Each direct digital synthesizer is programmed from a common digital processor with specific time and phase delay information such that the signals from the array combine to form a desired antenna pattern. To receive signals, signals from each antenna element in the phased array are processed by analog to digital converter. The digitized signals are then pre-processed in a time and phase delay preprocessor which receives time and phase delay information from a corresponding direct digital synthesizer prior to signal combining in a common digital processor.

Abstract: A low noise wide tuning bandwidth voltage controlled oscillator employs a resonator circuit formed from at least two microstrip lines which are electromagnetically coupled to one another. Each of the microstrip lines has one end electrically coupled to circuit ground to provide a substantially inductive resonator circuit which is substantially immune to parasitic end effects and radiation loses. The frequency of the voltage controlled oscillator circuit is controlled by a variable capacitance varactor circuit coupled to at least one of the microstrip transmission lines. The resonator circuit is well suited for use with a bipolar transistor configured as a negative resistance oscillator.

Abstract: A communication system for transferring data through the air over a relatively short fixed distance comprising a transmitting antenna which comprises a leaky coaxial cable for radiating electromagnetic energy modulated with data to be transferred; and a plurality of non-linear fixed beam array antennas for receiving the modulated electromagnetic energy from the leaky coaxial cable. The plurality of fixed beam array antennas are juxtaposed with the transmitting antenna such that the transmitting antenna extends at least partially through the near-field regions of the plurality of fixed beam array antennas. The communication system also comprises a selection means which determines which radio frequency output from the plurality of non-linear fixed beam array antennas exhibits the greatest radio frequency power and outputs that particular radio frequency output to a receiver.

Abstract: A continuous wave (CW) integrator is employed within a compressive receiver to improve the sensitivity of the compressive receiver to CW signals. The CW integrator circuit partitions the bandwidth of the compressive receiver into a series of contiguous bins and integrates any signals residing within these bins over many sweeps of the compressive receiver bandwidth. By sampling and integrating CW signals present in the compressive receiver bandwidth, the CW integrator circuit improves the sensitivity of the compressive receiver by a factor approximately equal to 10 log .sqroot.N, where N is the number of integrations performed.

Abstract: Apparatus for detecting molecular vapors in an atmospheric region includes an interferometer which monitors light parameter data signals received and provides an interferometer light parameter signal corresponding to the light parameter data signals at a plurality of frequencies. The apparatus further includes an interferogram detector/converter which records and digitizes the interferometer light parameter signal to generate a plurality of discrete data points wherein each discrete data point corresponds to the interferometer light parameter signal at a specific frequency. The apparatus also includes a Fourier transform circuit for receiving the discrete interferometer light parameter signal and providing a Fourier transformed molecular parameter data signal. The apparatus further includes a probabilistic neural network for receiving and sorting the Fourier transformed molecular parameter data signals without the use of a priori training data.