Abstract: A direction-finding antenna includes at least a first set of radiating elements configured to radiate at least a first wavelength (?1) and a second set of radiating elements configured to radiate at a second wavelength (?2) that is shorter than the first wavelength (?1). The first set of radiating elements defines a first circle having a first radius. The second set of radiating elements defines a second circle having a second radius that is smaller than the first radius of the first circle. The direction-finding antenna further includes a transmission line-based multiplexer configured to selectively couple the first set of radiating elements or the second set of radiating elements to a radio frequency (RF) feed line, or a plurality of switches configured to selectively couple selected radiating elements of the first set of radiating elements or the second set of radiating elements to the RF feed line.

Abstract: The invention relates to a method for determining features of an electromagnetic wave received by a reception system (22), the reception system (22) comprising at least two reception channels (13), each reception channel (13) comprising an antenna (21) and a reception chain (14), each reception chain (14) being capable of delivering a value representative of the power delivered by the corresponding antenna (21) after reception of the wave by the reception system (22), the features comprising at least the direction of arrival of the received wave, the method comprising a step of providing a measurement vector, the method further comprising the following steps: comparing the measurement vector to calibration vectors, and determining features of the received wave from the result of the comparison.

Abstract: A multifunctional radar transmitter may comprise bus interface circuitry and beamforming circuitry. The beamforming circuitry, with use of a plurality of beamforming coefficients, is operable to process a plurality of baseband signals to generate a millimeter wave radar burst corresponding to a radiation pattern that comprises a first lobe and a second lobe, where the first lobe is at a first angle and the second lobe is at a second angle. The bus interface circuitry is operable to receive, from a first receiver, an indication of interference from the second lobe present at the first receiver. The beamforming circuitry is operable to adjust, based on the indication of interference, the beamforming coefficients such that the second lobe is redirected to a third angle.

Abstract: A position tracking system for tracking a physical location of a radio frequency (RF) transmitter comprises at least four RF receiver antennae at known locations. Each receiver antenna receives RF signals from the RF transmitter. One receiver antenna is used as a reference antenna. A receiver channel unit is in communication with the RF receiver antennae. The receiver channel unit comprises a reference receiver channel and a measurement receiver channel. A multiplexer is dynamically configurable to selectively connect the reference receiver channel to the reference receiver antenna and to connect, in succession, each other receiver antenna to the measurement receiver channel. A comparator measures phase differences between the RF signals received by the reference antenna and those received by each other receiver antennae. A data processor computes the physical location of the RF transmitter from the phase differences measured by the comparator and the known locations of the receiver antennae.

Abstract: A high gain multi-beam aircraft blade antenna of an air-to-ground antenna systems includes multiple columnar matrix antenna elements housed within a blade. The elements are arranged to create independently steerable directed beams. A first independently steerable beam is used to provide communication. A second independently steerable beam is used to simultaneously search other signals.

Abstract: A method for determining a position of an emitter relative to a plurality of receivers is provided. The method includes emitting first and second signals at the emitter and receiving the first and second signals at each receiver of the plurality of receivers. The method also includes steps for establishing a first detected wave of the second signal as a lost wave or a gained wave for each receiver of the plurality of receivers. Detecting lost and gained waves assists with increasing the accuracy of a calculated location of the emitter relative to the plurality of receivers.

Abstract: An antenna includes a feed segment for transmitting a radio-frequency signal, a first radiator electrically connected to the feeding segment and formed on a first surface of a substrate, and a second radiator electrically connected to the feeding segment and formed on a second surface of the substrate, wherein the first radiator includes a first arm electrically connected to the feeding segment, a first branch and a second branch, and a second arm electrically connected to the feeding segment, a third branch and a fourth ranch, and the second radiator includes a third arm electrically connected to the feeding segment, a fifth branch and a sixth branch, and a fourth arm electrically connected to the feeding segment, a seventh branch and an eighth branch.

Abstract: An element of a phased array antenna is provided. The element comprises a phase tracking circuit configured to multiply the in-phase component (In) of a local output signal by the quadrature phase component (Qout) of an external output signal to generate a phase control signal (535) and/or to multiply the quadrature component (Qn) of a local output signal by the in-phase component (lout) of an external output signal to generate a phase control signal (535).

Abstract: This system and method provides a direction finding system that enables modern RF DF systems to analyze short duration signals in the entire instantaneous bandwidth. By providing a method to process wideband data, the invention drastically improves throughput and probability of intercept (POI). The invention is unique in that it does not require separate narrowband channels for analysis, and can simultaneously calculate azimuth and elevation estimates for every frequency in the bandwidth of an incident signal. It is also well-suited for fixed point, FPGA implementations making it a perfect match for modern state-of-the-art processing systems. The system and method capitalizes on the ability of Fourier Frequency Transform operations to accurately resolve incident wave phase at discrete frequencies. The system then uses the phase information from the individual elements in the array to arrive at an emitter azimuth angle.

Abstract: A system and method for distributing the power of an electromagnetic signal is presented. In one embodiment, a power distribution cavity includes, a planar cavity, input ports and output ports. The planar cavity is formed with a metallic sheet in the shape of a star pattern with a plurality of elongated star arms extending from a round center portion of the metallic sheet. The input ports are attached to the round center portion of the metallic sheet for receiving an input signal. The signals entering the cavity from the input ports creating independent resonant modes within the cavity that combine producing a tapered aperture distribution of signals at the output ports. The output ports are attached near to the outward ends of the elongated star arms. The planar cavity is thus configured to propagate electromagnetic fields at the output ports that were excited within the cavity by the input ports.

Abstract: An electrically tilted antenna system with polarization diversity has a dual polarized, tilt adjustable antenna (32). The antenna (32) has dipoles (34, 36) of two orthogonal polarizations associated with independently adjustable electrical tilt angles. The tilt angles are implemented by relative delays between corporate feed input or output signals, the delays being introduced by an antenna tilt assembly (54). Two signal feeders (F21, F22) associated with different antenna polarizations connect the antenna tilt assembly (54) to a base station filter assembly (50): the base station filter assembly 50 routes transmit signals from base stations (BS21, BS22) to different antenna polarizations via respective feeders (F21, F22) and the antenna tilt assembly (54). This assembly also divides receive signals from feeders (F21, F22) between both base stations (BS21, BS22).

Abstract: A system for indicating the relative direction of a target object or location as determined from the current position of a wireless communication device. The system employs Direction of Arrival determination using an antenna array for indicating the direction of a target device and includes facilities to activate a location-indicating transmission in a target device, the ability to request that a location-indicating transmission be activated in a remote target device, relevant information reception from a target device and the display of all potential target devices within effective transmission range of the wireless communication device.

Abstract: A hybrid wireless network system is disclosed. The hybrid wireless network system includes an antenna array, an analog subsystem, and a digital subsystem. The antenna array at least includes two antenna elements. In the case of using multiple antenna elements to extend link range and coverage, a coarse-fine method is included for antenna elements selection. The analog subsystem calculates a difference signal and a sum signal based on the two RF signals. The analog subsystem includes step leveling devices. The digital subsystem estimates a direction-of-arrival (DOA) based on the sum signal and the difference signal. The step-leveling devices receive weights from the digital subsystem, in form of a feedback control, to apply the weights on the two RF signals respectively. The digital subsystem repetitively calculates new weights to update a beam pattern formed by the two RF signals until the DOA approaches null.

Abstract: A multi-antenna station with distributed antennas and capable of providing good performance for terminals distributed throughout the coverage area of the multi-antenna station is described. The multi-antenna station includes multiple antennas, a controller, and at least one transmitter unit. The multiple antennas are coupled to the multi-antenna station and include at least one remote antenna that is located away from the multi-antenna station. The controller selects a set of one or more antennas from among the multiple antennas for data transmission to a terminal. The at least one transmitter unit transmits data to the terminal via the set of one or more antennas.

Abstract: Prior adaptive antenna systems can reduce effects of a jamming or interfering signal by reducing antenna gain in the direction of such signal. However, direction finding capability to enable location of the source of such signal in order to permit corrective or other action has not been available on an economical, low computational basis. Described systems and methods provide correlation matrix estimation to enable direction finding. In an embodiment, a beamformer unit derives an adaptive output signal with use of odd symmetry sequence perturbation signals and weighting signals developed with use of odd symmetry sequence perturbation signals. An extractor unit utilizes even symmetry sequence perturbation signals to process a form of the adaptive output signal, in derivation of output signals representative of a correlation matrix usable for direction finding.

Abstract: In a direction finding system, pluralities of signals provided by different sets of less than all of a plurality of arrayed antennas are code division multiplexed, downconverted by a single receiver, A/D converted and separated to derive signals that are processed to estimate the directions of arrival of the signals received by the different sets of antennas at different frequencies. The signals from different antennas are coded with different codes that have a common M-sequence and different phases for the different antennas. The derived signals are processed to detect the presence of signals and simultaneously demodulate and estimate the directions of arrival of signals by the antennas at the different frequencies. The different sets of antennas from which the received signals are provided for coding and multiplexing are selectively varied in accordance with the estimated directions of arrival and estimated magnitudes.

Abstract: The present invention relates to estimating the Angle of Arrival (AoA) of a signal from a user equipment received at a base station of a wireless telecommunications network where the base station has a multi-beam antenna. A signal received from a user equipment is received by the each of the multiple beams of the antenna, and the two adjacent beams receiving the highest amplitude from the end user are selected. A ratio of functions of the amplitudes of the two selected beams, such as a ratio of the difference between the amplitudes of the two beams to the sum of the amplitudes is calculated and compared to a data store of ratios. The data store stores expected ratios corresponding to AoAs and the calculated ratio is compared to the pre-calculated expected ratios to extract an estimate of the AoA of the signal from the user equipment.

Abstract: In order in simple manner to switchably cover a wide angle in sectors using an antenna array with broad main lobe, an antenna elements are so arranged, that the elements can be individually selected, so that some elements of the array can be operated in-phase and other elements operated in phase-opposition relative to each other. In order to determine the entry direction of a received signal, it is possible to operate the antenna array with non-symmetric antenna diagram, or however also to additively influence the symmetry of antenna characteristic by the use of a supplemental receiver element.

Abstract: A method and apparatus for estimating a communication channel in a wireless communication system having multiple transmitter antennas using reduced rank estimation. The method exploits redundant and/or a priori knowledge within a system to simplify the estimation calculations. In one embodiment, a covariance matrix is calculated and analyzed to determine if the channel parameters may be reduced for channel estimation. If not, all parameters are used, otherwise a reduced rank matrix is used for the calculation.

Abstract: Active high density multi-element antenna system [DS] for radiolocation of RF target radiation has a processor-controlled antenna array [CAA] having rings [R1, R2, R3] concentric about a central axis to define arcuate sectors Sn about the central axis, each ring having adjacent p.c. boards [PC1, PC2, PC3] with PIN diode-switched antenna elements within sectors. The rings provide three rings [E1, E2, E3] of discrete dipolar elements, defining electrically isolated antenna units [ASm], each radial to the central axis, of quasi-log-periodic configuration. Antenna units are switched in rotational sequence about the central axis to provide narrow beam signal selectivity, directionally rotatable about the central axis. An array control system [ACS] is operated, as under microprocessor control [34], by a host system [HS] to cause RF scanning. PIN diode switching is used on printed circuit boards within the array.

Abstract: Radio-signal direction finding is performed in the following manner. There is a plurality of antennas (A) at different locations. A switchable antenna coupler (SAC) switches (SW) from one antenna (A[i]) being coupled to a radio-signal input (INP), to another antenna (A[i+1]) being coupled to the radio-signal input (INP). A radio-signal processor (ASP) processes a radio signal (AS) which is present at the radio-signal input (INP) so as to obtain a phase-detection input signal (PDIS). A phase-change detector (PCD) detects a phase change (&Dgr;&phgr;) in the phase-detection input signal (PDIS) due to the switching (SW) from the one antenna (A[i]) to the other antenna (A[i+1]). A calculator (CAL) calculates the direction (DIR) of the radio-signal source (SRC) on the basis of this phase change (&Dgr;&phgr;). This manner of performing radio-signal finding can be implemented at relatively modest cost because it requires only one radio-signal processor.

Abstract: A communication system has a primary radio station and a portable radio station. The primary radio station communicates with the portable radio station. The portable radio station is freely three-dimensionally orientable with respect to a fixed coordinate system. The portable radio station has a transceiver, a controllable antenna structure, and a beam directional controller for three-dimensionally controlling a beam radiated by the controllable antenna structure. The portable radio station further has a three-dimensional geometric sensor for three-dimensionally sensing a local magnetic field. The beam is controlled on the basis of the sensed local magnetic field.

Abstract: A directional antenna connected to a portable communications transceiver is adaptively directed towards a remote station in a communication system. The amount of RF power required by the portable device is significantly reduced, relative to a non-directional antenna. The operational period of the transceiver between battery recharges is therefore considerably maximized.

Abstract: A receiver system for measuring the bearing of a target having ambiguity correction. The receiver system includes a four element antenna array, three receivers and two phase detectors. The system further includes switching means for selectively connecting the antenna elements to the receivers and the receivers to the phase detectors to obtain two pairs of bearing components, from which the target bearing is computed.

Abstract: Direction finding apparatus comprising at least ten antenna channels for connection to respective antennae in use, at least five receiver channels each coupled to at least two different antenna channels constituting a group, and circuitry for receiving and comparing the outputs of the receiver channels to determine the angular location of the signal source; the arrangement being such that in use the antennae of each group of antenna channels have a sufficient angular separation such that only one is capable of detecting the signal source at one time, and the nearest neighboring antennae of each group are coupled to respective different receiver channels different from the receiver channel of that group.

Abstract: The present invention concerns an apparatus and method for measuring the azimuth and elevation of an object. The apparatus includes a platform; a base plate arranged to the construction of the platform rotatably in a plane, which is essentially horizontal; a sensor frame attached to the base plate; at least three sensor elements attached to the sensor frame; and an electronics unit for the control of the sensor elements, capable of performing the processing of signals received by the sensors. The sensor frame is rigidly attached to the base plate and the directional pattern of the sensor elements is such as to cover the entire angle span of interest in the elevation plane, while the pattern covers an essentially narrower angle in the azimuth plane. The direction finder does not easily lose the tracked object performing movements particularly in the elevation plane.

Abstract: A system using two magnetic quadrupole antennas, two magnetic dipole antennas and means for processing the respective antenna signal outputs provides unambiguous estimates of elevation and polarization for an incident RF signal. The system uses an efficient procedure to process the signals from a small aperture array of fixed loop elements for the purpose of providing radio direction of arrival information that is free of intrinsic polarization error. The directional information is developed by performing a simultaneous arctangent operation on signals output from the antennas or as the measured phase difference between a quadrature summed quadrupole output and a quadrature summed dipole output compensated by a phase offset between the dipole antennas and the quadrupole antennas.

Abstract: A circular waveguide section which is suitably excited with a TM.sub.01 and two spatially orthogonal TE.sub.11 modes to form a cosine-squared-on-a pedestal amplitude distribution at the outputs of the circular waveguide. The resulting cosine-squared-on-a-pedestal amplitude taper may be distributed to the elements of a circular phased array to form a low sidelobe antenna. Since the waveguide is a reciprocal element, it can be used in a receiver as well as a transmitter.

Abstract: A method and apparatus is provided for deriving the direction of a received signal from a signal source using first and second orthogonally-mounted loop antennas and an omnidirectional antenna. In operation, output signals from each of the antennas are generated and repeatedly supplied to signal processing circuitry in a cyclical fashion as the receiver is rotated to locate the transmitter. The amplitudes of the output signals from the first and second loop antennas are then compared to determine whether the signal source is located in a null of the second loop antenna. If so, a null indication signal is generated. The phases of the output signals from the second loop antenna and the omnidirectional antenna are compared to determine whether the received signal is being received in a predetermined region of the second loop antenna. If so, an ambiguity indication signal is generated.

Abstract: A direction determining system having a Global Positioning System (GPS) receiver, a linear antenna array and a fast switching facility, the linear antenna array comprised of at least two antenna elements and the GPS receiver including two Costas Loops. The fast switching facility permits an input signal received by the two antenna elements to be processed and alternately supplied to the Costas Loops in synchronism for measuring the phases of the input signals received nearly simultaneously. The phase difference between the output signals of the two Costas Loops is measured in a phase meter and the pointing angle of the linear antenna array relative to the direction of a GPS satellite is determined by interferometry.

Abstract: A radar system includes a clock for generating timing signals of a predetermined period, an exciter for generating high frequency signals of predetermined frequencies in sequence and in time series in response to the timing signals, a transfer switch and an antenna. The transfer switch has an input terminal and a plurality of output terminals. The input terminal receives the high frequency signals and provides one of these high frequency signals at each of its outputs in accordance with the received timing signals. The antenna is connected to receive the high frequency signals from the output terminals of the transfer switch to form radar beams corresponding to the high frequency signals.

Abstract: An apparatus to confirm an orientation of the stem of ship by making use of a satellite included in the Global Positioning System. Radio wave signals from the satellite are received by a directional or omnidirectional antenna and the phase difference between a rotating period of said antenna and either the period of distance fluctuation, Doppler fluctuation, phase fluctuation or amplitude fluctuation is detected to obtain an orientation of the satellite which is used to obtain an accurate orientation of the stem relative to a reference direction such as due North.

Abstract: An interferometer type DF system uses an array of five antennas (A,B,C,D,E) arranged at the apices of a regular pentagon to define five wide apertures along the sides of the pentagon and a further five apertures along the diagonals. The phases of the signals received by each antenna, are measured modulo 2.pi. and processed to give a unique bearing of the radio source to the accuracy of the widest aperture defined by the array. One method of processing the phases is to calculate from them the Fourier coefficients of the Fourier series representing the spatial phase distribution. By comparing the difference between each calculated coefficient and a corresponding order coefficient of a set of imaginary antenna phases expressed as integral multiples of 2.pi., the complete 2.pi. phase differences between the measured phases modulo 2.pi. can be found.

Abstract: A radio direction finding system comprises a receiving portion for receiving a radio signal and a direction determining portion coupled to the receiving portion for developing a direction signal corresponding to the direction of arrival of a received radio signal. A memory is also provided for storing direction data corresponding to the direction of arrival of at least one received radio signal, and a control circuit is coupled intermediate the direction determining portion and the memory for producing direction data corresponding to the direction signal for storage by said memory. In accordance with a further aspect of the invention, an indicator is provided for actuation by the control circuit to produce an observable indication of the direction of arrival of a received radio signal, and the direction finding system further includes an EPIRB detector portion for producing an EPIRB reception signal in response to reception of an EPIRB signal.

Abstract: A horizon reference system has a plurality of microwave radiation sensors which are selectively connected by a controller to a superheterodyne receiver. The output signals of the receiver are processed in conjunction with antenna selection data to provide roll angle with reference to the horizon and roll angle rate data about any particular axis of the platform on which the sensors are mounted.