Hughes Aircraft Company

Raytheon Company

Frederick C Williams

Elvin E Herman

Clarence A Greene

William W Clements

Andrew E Vall

Wolfgang H Kummer

There is disclosed an elevation null command generator (ENCG) for use in airborne monopulse radar, and a novel missile guidance system made possible by use of the ENGC. The ENCG provides an accurate means of directing the elevation monopulse plane of a radar antenna at a patch of ground defined by a range signal generated within the radar or its associated equipment. It is shown that within the system range can define the elevation angle of concern. The ENCG includes a central range gate centered at the command range and a plurality of pairs of range gates, the two gates of each pair being time spaced before and after the central range gate, and has circuit means for normalizing the output of the range gates to eliminate the bias effects of strong targets adjacent to the monopulse null plane and ground surface intersection.

Elevation null command generator for monopulse radar airborne missile guidance systems

This disclosure relates to an improved airborne monopulse radar system used for tracking ground targets. The system includes a null command generator designed to provide an error signal proportional to the angle between a preselected target azimuth and the monopulse antenna difference pattern null azimuth which error signal is unaffected by the presence of moving targets within the area under radar surveillance. The error signal is applied to the monopulse antenna drive servomechanism in order to physically reorient the antenna to have the difference pattern null and the preselected target aligned along the same azimuth.

Monopulsed radar system for tracking ground targets

A synthetic array processor wherein radar data, received from an area to be mapped during a plurality of subarray flight path segments, is electronically focused in parallel processing channels to form a series of approximately rectangularly shaped low azimuth resolution maps; and signals associated with corresponding portions of each low resolution map are further processed by means of digital filtering techniques to provide, in a format readily adapted for display, a high azimuth resolution map.

Synthetic array processor

The herein disclosed electronically scanned antennas comprise a plurality of frequency scanned antenna sections each of which have a plurality of radiating elements and a plurality of phase shifters individually coupled to the antenna sections. Spatial steering of the beam over a predetermined angular subtense is provided in response to a change in frequency of the applied electromagnetic energy. The phase shifters are programmed to adjust the relative phase of the energy processed by each of the antenna sections so as to provide an energy beam having a coherent phase front. A first embodiment incorporates a plurality of serpentine feedlines disposed in a linear arrangement along with a plurality of phase shifters coupled thereto, which cause the plurality of feedlines to have the electrical characteristics of a single continuous feedline. A second embodiment incorporates the plurality of phase shifters as adapted to a thinned array antenna configuration.

Electronically scanned antenna

There is herein described a wide-band, phase scanned transmitting antenna with a greatly reduced bandwidth/scan angle limitation through the use of a time variable phase shifter coupled to the input of each phase scanned sub-array of the antenna.

Wide-band, phase scanned antenna

The method and apparatus for processing bipolar coherent sidelooking radar data to achieve continuous real time synthetic array mapping in the form of focused line-by-line imagery. Received radar data is correlated such that a number of subarrays are vectorially combined with appropriate quadratic phase corrections to continuously form the total synthetic array. Each subarray is accumulated in a recirculating (feedback) channel which applies a linear phase correction and amplitude weighting, which in turn reduces the arithmetic operations required to form the array. The subarrays are updated by continuously subtracting out the oldest data and adding new data to yield continuous line-by-line imagery. Alternate accumulator and feedback channels are employed in an interleaved fashion to minimize the buildup of 'round-off' errors which result from digital multiplications. The invention is adaptable to all-range-focusing and operation at various pointing angles.

A system for automatically focusing a synthetic array through derivation of focus error signals which may be used such as by summing a priori data so that the synthetic array data may be optimally focused. Focus error data is derived by forming the synthetic array in three sub-array. The resultant outputs of these three sub-arrays are further processed together to extract data corresponding to the degree of total array defocus. For purposes of imagery generation, the phase and amplitudes of these three sub-array resultants are vectorially summed together and the resultant is magnitude detected to yield imagery output corresponding to the full synthetic array. For derivation of focus error data, the mean (bisector of the relative phase angle between the two end sub-array resultant vectors is measured. This derived bisector's phase angle is compared to the phase angle of the central sub-array resultant vector. The angle of the bisector relative to the central sub-array resultant is representative of the degree of defocus, and the sign of the angle is indicative of whether the array is over or under-defocused. For a properly focused array, the bisector of the two outer subarray resultants is in phase with the resultant vector of the center sub-array.

Synthetic array autofocus system

A thinned array real time radar system having an antenna array with receiving elements spaced more than one wavelength apart and having a dynamic means for programming the focus of the array so that it is time sequentially focused to accommodate radar echoes over a range interval from a near range out to infinity to provide an improvement in azimuth resolution, the improvement being substantially large for the near ranges. The system includes a separate mixer for every element of the array for receiving return energy therefrom and with each mixer having a separate local oscillator input. The local oscillator frequency varies as a prescribed first function during each period of processing over the selected range interval and the path length distribution of the feeds between the local oscillator and each individual mixer vaires as a prescribed second function. The first and second functions may be separable functions of an expression approximating the time-space variations of the spherical phase front received by the antenna array. The local oscillator feed is selected so that the distance from the local oscillator to each particular mixer varies as a function of the distance squared from the center of the array or processing point of the array.

Growing community of inventors

Topanga, CA, United States of America

Frederick C Williams