Abstract: An antenna for a base station comprising a plurality of antenna arrays (40; FIG. 6a) each capable of forming a multiplicity of separate overlapping narrow beams in azimuth, the arrays being positioned such that the of beams formed by the arrays provide a coverage in azimuth wider than each array. Means are provided for recognizing unique identifier signals (70; FIG. 6b) incorporated in call signals passing through the antenna; and coherent detection means for discriminating between unwanted call signals and wanted call signals using said unique identifier signals.

Abstract: A phased array radar antenna uses time-steering subarray notch weightings to produce a wideband notch in the direction of interference for Electronic-Counter-Measure (ECM) interference suppression. A predetermined set of subarray notch weightings, each set being identical for each subarray, is stored in controllers each of which is coupled to a plurality of phase shifters and attenuators for feeding radiating elements of the antenna. Interference suppressors operate from a plurality of controllers to produce a subarray pattern having a notch in the direction of interference. Beamformers then combine outputs of all time-steering subarrays in the antenna so as to produce an antenna pattern having a wideband notch in the direction of interference.

Abstract: An array system with radiating elements and a wideband monopulse power divider network with dual channel input ports and multiple output ports. Each input channel of the network excites a uniquely different RF amplitude and phase distribution out of each of the corresponding "n" output ports. All ports are matched and isolated from each other across a wide instantaneous frequency. Also the RF power distribution will track in amplitude and phase across a wide frequency band. This is achieved through a special arrangement of air-stripline matched power dividers, attenuator, phase shifters, and Magic-Tee couplers. The output ports of the network can be connected directly to the radiating elements or to partitioned feed circuits which are in turn connected to sub-sets of the radiating elements.

Abstract: A multi-mode seeker which comprises a stationary antenna and electronic circuitry responsive to signals received by the antenna to cause the antenna to scan a field of view determined by the signals received by the antenna. The seeker has a nose region positioned at the forward portion thereof and an adjunct sensor disposed in the nose region ahead of the antenna. The electronic circuitry includes circuitry for performing a Sum/Delta monopulse processing technique on the signals received by the antenna the Sum/Delta monopulse processing including calculating each of a standard Sum signal, Delta-Azimuth signal and Delta-Elevation signal. The seeker has a boresight axis, the center of the field of view being off boresight, in general. The seeker has a field of regard, the field of regard having plural sectors, each of the sectors having separate predefined compensation.

Abstract: A digital beamforming array for use in radar applications and particularly in radar applications that used phased array technology. The array receives an incoming signal at a plurality of sensor modules, converts them to intermediate frequency, and then converts the intermediate frequency signals to n-bit (preferably 1-bit) digital signals at an oversampling rate, where n is less than the number of bits required to represent the dynamic range of the intermediate frequency signal. The n-bit digital signals are then beamformed by altering their relative phases and combining them to form a resultant n-bit digital signal which is then converted to a digital signal of the number of bits required to represent the dynamic range of the intermediate frequency signal. An advantage of the present invention is that it reduces the complexity and thus the cost of the digitizing hardware required.

Abstract: A radar antenna includes a reception part constituted by elementary antennas, each elementary antenna delivering a reception signal to a computer for the formation of simultaneous radar beams by computation, and a transmission and reception part constituted by at least one elementary antenna. The computer uses the signals received by the elementary antennas of the reception part to form a set of radar beams within a solid angle radar beam formed by the elementary antennas of the transmission and reception part. The radar antenna finds particular application in the field of designation and trajectography radar.

Abstract: A true time delay phased array is provided which includes a digital subarray interface in the transmit signal path. The digital transmit signal path interface includes a digital reference signal generation means and digital signal propagation means for supplying the digital reference signal to the subarray. Each subarray includes RF carrier signal generating means for generating an RF carrier signal phase coherent with the reference signal, a fiber optic true time delay circuit for applying an appropriate phase delay to the RF carrier and an appropriate true time delay to the modulation signal, and a waveform modulator for modulating the modulating signal onto the phase locked RF carrier signal to provide the transmit signal for the subarray. The present invention can be used in conjunction with existing digital interface technology for receive and control signal paths to provide an entirely digital subarray signal path interface.

Abstract: An improved system is disclosed for controlling the operation of a transmit/receive module in a phased-array antenna system. The improved module control system of the invention is implemented in a simple integrated circuit chip and may be co-located with a transmit/receive module positioned at an antenna array element. Either fully distributed or row/column distributed beam steering architecture may be implemented by the improved module control system with both speed of operation and cost advantages realized over prior art systems.

Abstract: An optically based feed structure is used to distribute appropriately phased signals from a central signal generator to the individual elements of a phased array antenna. Any phase can be generated by adding together four phased signals (phased by 90 degree increments) if the amplitudes of the individual phased signals are appropriately controlled. By appropriately controlling the amplitude of the individual phased signals the amplitude of the resultant can also be controlled. In many cases it is desired to keep this amplitude constant. In some cases an amplitude taper across the phased array is desired.

Abstract: A method of and an apparatus for measuring the null angle in the difference vs. sum pattern and in the difference pattern of a monopulse antenna. The null angle of the monopulse antenna in the radiation pattern is acquired by transmitting an RF signal from a plurality of antenna elements to the monopulse antenna, acquiring the sum signal and difference signals in the directions of the respective antenna elements and acquiring the null angle in accordance with the sum and difference signals. The apparatus comprises a rotator for changing the direction of the monopulse antenna and a transmitting antenna facing the monopulse antenna for transmitting a test signal to the monopulse antenna.

Abstract: An AWTSS is shown to be made up of an improved synthetic aperture radar (SAR) for generating radar maps with various degrees of resolution required for navigation of an aircraft and detection of ground targets in the presence of electronic counter-measures and clutter. The SAR consists, in effect, of four frequency-agile radars sharing quadrants of a single array antenna mounted within a radome on a "four axis" gimbal with a sidelobe cancelling subarray mounted at the phase center of each quadrant. Motion sensors are also mounted on the single array antenna to provide signals for compensating for vibration and stored compensating signals are used to compensate for randome-induced errors. In addition, a signal processor is shown which is selectively operable to generate radar maps of any one of a number of desired degrees of resolution, such processor being adapted to operate in the presence of clutter or jamming signals.

Abstract: An AWTSS is shown to be made up of an improved synthetic aperture radar (SAR) for generating radar maps with various degrees of resolution required for navigation of an aircraft and detection of ground targets in the presence of electronic countermeasures and clutter. The SAR consists, in effect, of four frequency-agile radars sharing quadrants of a single array antenna mounted within a radome on a "four axis" gimbal with a sidelobe cancelling subarray mounted at the phase center of each quadrant. Motion sensors are also mounted on the single array antenna to provide signals for compensating for vibration and stored compensating signals are used to compensate for radome-induced errors. In addition, a signal processor is shown which is selectively operable to generate radar maps of any one of a number of desired degrees of resolution, such processor being adapted to operate in the presence of clutter or jamming signals.

Abstract: An azimuth-stacked radar method and apparatus of the type typically used for surveillance employs a mechanically-rotating antenna comprising horizontal end-fed rows of antenna radiating elements with phase shifter control on each row together with a monopulse elevation manifold to generate an elevation sum and difference beam pair. Additionally, this radar employs a waveform comprising multiple subpulses at different frequencies with sufficient separation between the subpulses at each frequency to spread them in azimuth to form a beam cluster and employs mechanical antenna rotation and phase-responsive elevation scanning. The scanning is accomplished in a way that will permit advantageous avoidance of ground clutter and other uninteresting radar reflectors.

Abstract: A monopulse antenna array arrangement includes a transmit-receive processor (TR Proc) associated with each antenna element. Each TR Proc has a port associated with the radiating element and at least two further ports, one for a sum beamformer and another for a difference beamformer. Within each TR Proc, a switching arrangement allows transmitter signal to flow through a phase shifter and transmit amp during transmission, and allows received signal to flow through a low-noise amp and the same phase shifter on reception. Each TR Proc includes a coupling arrangement with a second phase shifter and a second output port, adapted to be coupled to a difference beamformer during reception.

Abstract: A method of nulling out interference sources in a large-aperture phased ay radar system is described. The system has apriori knowledge of the interference sources and depends upon access to the array element phase shifters for injection of phase only or phase and amplitude perturbations, of a mainbeam aperture distribution, into said array element phase shifters. The phase or phase and amplitude perturbations are derived from an aperture ripple modulation algorithm. The system does not require any auxiliary elements or correlators or beamformers.A method of nulling out interference sources in a monopulse large-aperture phased array radar system is also described wherein the phase only or phase and amplitude perturbations are injected into both the sum and difference beams.

Abstract: A method of electronically stabilizing a monopulse antenna mounted on a movable body is disclosed. According to the disclosed invention, the monopulse antenna is electronically steered in a fixed direction despite motion of the movable body in relation to that direction. Compensated azimuthal and elevation difference signals are formed by approximately weighting and adding the the uncompensated azimuthal and elevation difference signals formed by the monopulse antenna.

Abstract: A multifunction active array system is disclosed, wherein the array aperture may be partitioned into a plurality of arbitrary subapertures. The array system includes N radiative elements, each coupled to a corresponding active module. Each module is in turn connected to an aperture partition selector, which includes an M-way power divider/combiner device, having a module port and M device ports. Each device port is coupled through an RF switch to a partition port of the device. M N-way manifolds are provided, having N manifold ports coupled to a respective one of said partition ports of each selector. The manifolds are coupled to a receiver and an excitation source. Each partition may be formed by the desired connection of a particular module to a manifold by the respective positions of the RF switches. The array system provides the capabilities of partitioning the array into M or less subapertures to simultaneously generate sum patterns, difference patterns, guard patterns, and adaptive nullings.