Abstract: A beam sharpened, low sidelobe antenna is obtained by segmenting the antenna to provide two sub-antennas, one of which is arranged as an interferometer. The output signals of the two antennas are added and subtracted to provide sum and difference signals. The sum and difference signals and the output signals are then utilized to provide the desired beam sharpened, low sidelobe antenna.

Abstract: A planar edge-slotted and end-fed traveling wave antenna is designed for monopulse operation, with an odd array of parallel elements interleaved with an even array of parallel elements. The even elements have an amplitude taper that is an arithmetic sum of Taylor and Bayliss amplitude tapers, while the odd elements have an amplitude taper that is an arithmetic difference of the Taylor and Bayliss tapers. Transmit energy is fed to both the odd and even elements, and the resulting radiation produces a pencil beam of a predetermined beamwidth for illumination of a distant target. The return excitation for the odd and even elements is combined to produce sum and difference monopulse patterns.

Abstract: In an air traffic advisory system for determining the bearing of an intruder aircraft relative to a protected aircraft, the preferred apparatus determines a corrected bearing to compensate for bearing errors caused by intruder signal reflections. More particularly, the preferred apparatus uses a hybrid combiner to produce a sum, delta one and delta two signals, and determines the phase relationship between the sum signal and each of the delta signals, the two phase relationships being subject to at least partially offsetting errors due to intruder signal reflections. The apparatus determines an uncorrected intruder bearing from each phase relationship and then averages the uncorrected bearings to produce a corrected intruder bearing.

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: An antenna system comprising two similar radiation antenna elements with a single monopulse feed system is scanned while transmitting in-phase radio waves from the two elements. Reflected radio waves are received by the two elements and fed to a hybrid circuit which in turn produces a sum signal .SIGMA. and a difference signal .DELTA.. After detection is performed by a detector, a signal processing unit subtracts the difference signal .DELTA. from the sum signal .SIGMA.. In this processing step, the output signal produced by the above subtraction process is actually output only if the receiving pattern waveform associated with the sum signal .SIGMA. has an upwardly convex form, that is, its double differential coefficient is negative and further if the receiving pattern waveform associated with the difference signal .DELTA. has a downwardly convex form, that is, its double differential coefficient is positive, whereby an antenna pattern with beam compression is provided.

Abstract: A nonrectangular antenna aperture is provided comprising four quadrants for receiving electromagnetic signals. The aperture has the capability to form a predetermined sum beam, a predetermined first difference beam, a predetermined second difference beam, and a predetermined double difference beam so that the product of the first and second difference beams is substantially equal to the product of the sum and the double difference beams.

Abstract: A monopulse tracking apparatus comprises first to fourth electromagnetic horns disposed symmetrically to each other in an azimuthal direction and elevation direction in a 2.times.2 matrix state, a first hybrid circuit for creating the sum signal and difference signal of the first and second electromagnetic horns, a second hybrid circuit for creating the sum signal and difference signal of the third and fourth electromagnetic horns, a third hybrid circuit supplied with the respective sum signals of the first and second hybrid circuits and for outputting the sum signal and difference signal thereof, a fourth hybrid circuit supplied with the respective difference signals of the first and second hybrid circuits and outputting the sum signal and difference signal thereof, and a fifth hybrid circuit for creating the sum signal and difference signal of the first and fourth electromagnetic horns or the second and third electromagnetic horns.

Abstract: After each received signal in the same two antennas of the monopulse power feed system are inputted into a hybrid circuit, a sum signal .SIGMA. and a difference signal .DELTA. are formed, and they are demodulated in detection circuits, zero is outputted if the value of the sum signal .SIGMA. is equal to or smaller than the value of the difference signal .DELTA., otherwise the value subtracted the difference signal .DELTA. from the sum signal .SIGMA. outputted, in a signal processing section. Thus, beam compression and reduction of a side lobe are performed.

Abstract: A tracking radar system comprising an aerial arrangement having a plurality of outputs, means for deriving from the aerial outputs a sum signal representative of the sum of the aerial outputs and a difference signal representative of the direction of a target relative to the aerial, a receiver for processing said sum and difference signals to produce corresponding intermediate frequency sum and difference signals, means for comparing the intermediate frequency sum signal with the output of an oscillator in a first phase-locked loop and using the resulting signal to control the oscillator frequency so as to cause the oscillator to lock on to the frequency of the intermediate frequency sum signal, a phase-sensitive detector for comparing the intermediate frequency difference signal with the output of the oscillator to produce an output signal representative of the phase difference between the sum and difference signals, and bandwidth alteration means responsive to the sum signal to alter the bandwidth of the fi

Abstract: A method for processing an antenna pattern in which a first antenna system is placed to correspond with a first direction in relation to the beam width to be compressed, a second antenna system of the monopulse power feed system is placed to correspond with a second direction lying at a right angle to the first direction, in which an antenna beam of the first and the second antenna systems is scanned in a direction other than the first and the second directions. A sum signal .SIGMA.1, a difference signal .DELTA.1 and sum signal .SIGMA.2, difference signal .notident.2 are formed in hybrid circuits, and an output signal two-dimensionally compressed are obtained as a result of adding a signal resulting from the subtraction of the difference signal .DELTA.1 from the sum signal .SIGMA.1 to a signal resulting from the subtraction of the difference signal .DELTA.2 from the sum signal .SIGMA.2 in a signal processing section.

Abstract: A secondary surveillance radar system in which monopulse processing is used to obtain angle estimation of azimuth bearing, the improvement residing in a precision method, involving a monopulse qualifier signal, for identifying the maximum unambiguous off-boresight azimuth (OBA), while ensuring reduced sensitivity to Omni channel variations; the monopulse qualifier signal is developed from coherently combining the IF limited signals derived from the Sum+JDelta and Delta+jSum signals, such that two amplitude varying signals are created, such signals bearing a direct relationship to the Sum and Difference antenna pattern ratios and being independent of antenna signal power.

Abstract: The invention is a radar system using sum and difference signals for tracking targets, wherein the system includes aperture means having a cross sectional area for transmitting energy toward a target and receiving return energy; and circuit means for generating sum and difference signals, the circuit means being selectively coupled to said aperture means, with the sum signal being generated using energy from the entire aperture means and with the difference signals being generated using return energy from the aperture means exclusive of energy from a predetermined area. The invention permits simultaneous optimization of the sum and difference signals and also suppresses the near-in sidelobes in the difference signals.

Abstract: An improved apparatus and method for radio direction finding is set forth, the generic function of which is that of an "automatic bearing indicator" (ABI). The technique and apparatus are intended for use in association with an antenna system which provides two directional beams which are scanned azimuthally in synchronism and are accessible simultaneously at two separate ports. The first beam is characterized by a response pattern having two adjacent, equal, lobes separated by a single, simple, null. The second beam is characterized by a response pattern having a single lobe, aligned in angle with the null of the first beam. The two signals from the two ports of the antenna system are directed via a twin channel receiving means, phase difference and amplitude detection means, and analog to digital conversion means, to data processing means under control of an algorithm which exploits the properties of the phasor (complex number) ratio of the first signal to the second signal.

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: A method of processing in a two-channel monopulse receiver and processor is shown to include the steps of: (a) forming composite signals equal to [S+(p+jy)] and [S-(p+jy)] where S in a monopulse sum signal and p and y are, respectively, pitch and yaw error signals; (b) alternately passing the composite signals through a two-channel amplifier; and (c) separating the components in the resulting amplified composite signals for conventional monopulse processing and smoothing to eliminate the effects of any imbalance (in phase or amplitude) between the channels in the two-channel amplifier.

Abstract: An angular position determining system utilizing an electronically scanned, linear phased array antenna radar system. The teachings of the present invention are applicable to airborne, ground or sea based radar systems for determining either elevation of azimuth. In one disclosed embodiment mounted in an aircraft for determining elevation, the linear phased array antenna is formed by a conformal wing array of radiating and receiving elements, wherein the phase front of the antenna beam can be controlled to steer the antenna beam by individually controlling the gain and phase excitation of each radiating element. The array comprises a left portion of the array and a right portion of the array, and each of the left and right portions is formed by a first plurality of elements tilted downwardly in elevation and a second plurality of elements tilted upwardly in elevation.

Abstract: A method for producing antenna follow-up signals in which a sum signal and a difference signal are derived from a received beacon signal and an amplitude modulated signal is produced by superposition from these two signals. The amplitude modulated signal is converted into another frequency by means of a mixer which receives both the amplitude modulated signal and a mixing signal. The converted amplitude modulated signal is fed to an amplitude detector via a narrowband bandpass filter which permits only the signal frequency to pass. A voltage controlled oscillator is cyclically switched to produce a mixing signal which is fed to the mixer and which cyclically changes its frequency between two frequencies for the duration of each phase state of the difference signal. The converted signal at the output of the mixer changes its frequency between two further frequencies in response to the change of frequency of the mixing signal.

Abstract: A monopulse comparator is formed by milling grooves in opposed surfaces of aluminum circular blocks. The milled grooves define a number of waveguides, ports and hybrid junctions. A, B, C and D ports are coupled by respective waveguides to respective side branches in first and second hybrid rings. The series branches of these hybrid rings are coupled by respective waveguides to parallel and series branches respectively of a third ring hybrid ring. One side branch of this hybrid ring is coupled to an azimuth differential port by one of the waveguides. The other side branch is coupled to a termination by a waveguide. The parallel branches of the first and second hybrid rings are coupled by respective waveguides to respective side branches of a fourth hybrid ring. The parallel branch of this hybrid ring is coupled by a waveguide to the elevation differential port. The series branch of this hybrid ring is coupled by a waveguide to the sum port.

Abstract: A mono-lobe tracker is described for tracking a target emitting radio signals incorporating an antenna, a circuit for sequential lobing, a radio frequency amplifier, a mixer, an intermediate frequency amplifier, an amplitude modulator detector, and integrators for storing the amplitude signals corresponding to predetermined off boresight positions, means for taking the difference of two integrators indicating the boresight error, a motor coupled to the error signal for driving the antenna in response to the error signal and a random number generator for generating at random a plurality of frequencies which are coupled as randomly selected to the sequential lobing circuit. A random number generator is also described incorporating a noise diode, an amplifier, a voltage comparator and a counter.

Abstract: A monopulse tracking system utilizing at least two channels, each of which has a different spreading/despreading pseudo-random noise function associated therewith. In conjunction with a monopulse antenna, one of the channels is utilized to develop a sum signal and the other channel is utilized to develop a difference signal, which sum and difference signals are utilized in a phase detector to generate an error signal. Because different channels are utilized to develop the sum and difference signals, externally generated noise is uncorrelated in the phase detector and, therefore, biases caused by the noise are eliminated.

Abstract: A monopulse receiving arrangement is shown to comprise orthogonally polarized and electrically separate monopulse antenna arrays, one such array being made up of juxtaposed slotted waveguides and the other being made up of at least one monopulse array of dipoles printed on a dielectric material.

Abstract: In an apparatus for maintaining the orientation of an antenna system with respect to a beacon, radio signals are received in four quadrants and converted into sum and difference signals, which are transformed in frequency, amplified in an amplifier (6) and detected in a first- and second-phase detector (9, 15) present in a corresponding channel (7, 8) to derive error voltages in first and second time intervals respectively for aligning the antenna system with respect to the beacon. During the tracking mode of the apparatus, the difference and sum signals separately pass in first, second and third, fourth time intervals, respectively. a VCO (21) supplies two orthogonal signals as reference voltages, to the phase detectors. In the tracking mode the VCO driven by a signal derived from the signals obtained in the first channel (7) in the fourth time interval and in the second channel (8) in the third time interval.

Abstract: This invention is directed to a modified monopulse comparator which includes two sum and difference hybrid junctions. The first hybrid junction produces a signal-free sample of any interference which is received by the datalink receiving antenna. The second hybrid junction is a standard monopulse comparator driven by amplified and filtered signals from the A and B antenna feeds after subtraction of the properly scaled and phased interference sample.

Abstract: A technique for reducing cross-polarized signals in the axis of four-port al-polarized antennas. The resulting lower cross-polarized signals reduce a tracking antenna's susceptibility to tracking errors and to breaklocks. Some energy from the transmission line connected to the (V) port is coupled, after proper attenuation and phase adjustment, and transmitted through the (H) port, thereby nulling out the (V) cross-polarized pattern.