Abstract: A phase shifter assembly for use with a phased array antenna includes a plurality of phase shifter subarrays which are mounted on a ferri-magnetic substrate. There is a common power feed which is connected in series through a transmission line with each of the phase shifter subarrays. Additionally, a plurality of power combiners/splitters are connected into the transmission line to direct the proportionate power to each subarray. An alignment phase shifter is connected into the transmission line between adjacent subarrays and their associated power combiner/splitter. Separately from the transmission line, a driver is electronically connected in series with coils at each of the alignment phase shifters to alter the phase power which is fed into each of the subarray to align adjacent subarrays and produce a substantially continuous wave for the antenna.

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: A multibeam phased array radar includes identical N:1 equal-split combiners and overlay hybrid couplers which form multiple tapered and weighted beams. The radar is configured with a single transmit/receive (T/R) module for each antenna element. The T/R modules contain a high power amplifier for transmit, low noise amplifier for receive, phase shifter for beam steering and attenuator for overall weighting. Each T/R module is connected to an unequal-split coupler which divides the received signal into signals of different amplitudes. Each of these signals are fed into a separate N:1 equal-split combiner, thereby forming separate beams. The illumination taper of each beam is determined by the coupling values of the couplers and the setting of the T/R module attenuator. There is disclosed a first embodiment including two beamformers and a second embodiment extending the concept to more than two beamformers.

Abstract: A spatially modulated Bessel beam radar system for enhancing the resolution with which a range and an azimuth of a plurality of closely spaced targets is determined. In a Bessel beam radar system, a Bessel beam is generated by sequential spatial modulation of the radar signal while maintaining a constant spatial polarization, and the return signal from one or more targets is processed to determine its Bessel function content. To spatially modulate the radar beam, the point at which the radar signal is transmitted is moved around a circular orbit. In a first embodiment of the spatially modulated Bessel beam radar system (80), a radar dome (86) mounted on the distal end of a mast (84) is pivoted around an orbit (90). The radar signal is transmitted in a predefined direction, along a Poynting vector that is generally aligned with the plane of the orbit. In a second embodiment (110), a plurality of parabolic antennas (116) are arranged in a spaced-apart circular array around a common center.

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: An antenna system comprises a plurality of element antennas for both transmission and reception of signals, which are constituted on an optical profile surface and are divided into a plurality of blocks, each including at least more than two element antennas; a plurality of miniature transmitters/receivers connected respectively to the plurality of element antennas, which are adapted to switch between a transmission mode and a reception mode, to control the phase shift of transmission signals and amplify the controlled transmission signals in the transmission mode or to control the phase shift of reception signals and amplify the controlled reception signals; a plurality of power supply circuits connected respectively to the plurality of blocks, each of which is adapted to distribute the transmission signals to the corresponding block, or to synthesize the reception signal from the corresponding block; a plurality of reception signal converting units connected respectively to the plurality of power supply cir

Abstract: An improved angle of arrival measurement technique for monopulse antenna systems employing phase shifters on each of the four feeds to resolve ambiguities and to increase the beam splitting (angle of arrival) accuracy. To resolve ambiguities, the phase shifters are employed to shift or steer the sum and difference beams a predetermined angular amount relative to a signal of interest, and the resulting change in the angle of arrival of the returned signal is noted. The position of the original signal, as displayed on an output device, such as a radar display, for example, is then compared with the position of the signal received with respect to the shifted beam. This comparison reveals whether a true signal has been received or not. If the signal of interest is intercepted in the main beam, then the position thereof after the beam has been steered remains in the main lobe of the beam, and hence the signal of interest remains detected.

Abstract: An electronically scanned radar system has a serpentine antenna, with at least two ports. The antenna is physically rotated. Each port has a mixer, transmitter and local oscillator feeding signals to it, the signals of the transmitter and oscillator being synchronized with one another to take advantage of the physical rotation of the antenna. The radar system can be operated in various ways to produce two independent beams simultaneously in a surveillance mode and/or tracking mode at each port. Furthermore, with the use of coupling means, the system can be operated to produce four independent beams at two different frequencies simultaneously. The system can also be operated to produce one or more beams in a surveillance mode and/or one or more beams in a tracking mode at each port. Further, the system can be operated to compensate for the physical rotation of the antenna and can avoid jammers by hopping to another frequency.

Abstract: An electronically scanned radiometer has a dispersive serpentine antenna with one or two ports. A mixer is connected to each port with each mixer being fed by a variable frequency local oscillator. Each oscillator provides the mixer to which it is connected with a drive signal that varies in frequency. The antenna most efficiently receives one or more beams through radiators at an angle that varies with the frequency of the drive signal at the mixer. An output is received at each port and is appropriately displayed. When the serpentine has two ports the radiometer can be operated at two orthogonal polarizations. The frequency being fed to each mixer can be varied in various predetermined patterns. Scanning of the beam can be effected by changing the frequency of observation without physically rotating the antenna. Also two simultaneous beams rotating in opposite directions with independent motions can be achieved.

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.

Abstract: A segmented phased array antenna system for scanning two different ranges of directions with a single set of antenna elements. The system comprises a plurality of segments (40), each of which has a plurality of antenna elements (48) mounted therein. The segments are mounted by support means (42, 44, 46) such that each segment is movable between first and second positions. In each set of positions, the antenna elements are operated as a conventional phased array radar system. The antenna system may be longitudinally mounted along the upper surface of the fuselage of an airplane (10) to provide side-looking radar coverage to both sides of the airplane.

Abstract: The invention relates to a radar system of the type which can be presented with a number of tasks to be performed. Some of these tasks, e.g. the surveillance of areas at close range, may only require the transmission of low energy pulses and thus the full potential of the r.f. energy source has not previously been used while such tasks are being handled. By arranging for the tasks to be performed in a suitable overlapping sequence the full capability of the energy source is used at all times thereby increasing the throughput of tasks.

Abstract: Microwave communication and radar systems that employ a blazed microwave reflection grating are disclosed in which the grating comprises an array of electrical conducting scattering elements having plane parallel surfaces that face in the same direction. The plane parallel faces are positioned in parallel equally-spaced planes to provide a generally stair-step, or Venetian-blind type structure. Microwave energy beamed onto the plane parallel surfaces of the array exits at a diffraction-mode angle within the reradiation pattern of the individual scattering elements of the array. Frequency steering of the exit beam in one plane of the array is provided by varying the frequency of the illuminating beam.

Abstract: A frequency agile radar system allows tracking of noncooperative targets with high accuracy. The system is particularly useful in an automatic landing system aboard an aircraft carrier. The radar employs an electronically steered planar array antenna system in which a symmetrical pencil beam of 1.degree. beamwidth is steered in 1/2.degree. steps in a raster scan. A space-stabilized acquisition window allows target acquisition, and target scanning modes are chosen as a function of target range. At far range, target scan is effected by those four beam raster positions which bracket the target whereas when the target is at near range where its cross section is larger than a single beamwidth, the raster is "ballooned" to paint or cover the target fully. The computed track of the target provides a continuing update of autopilot command signals radioed to the target to bring it to and hold it on a selected glideslope which effects the automatic landing.