Hughes Aircraft Company

Other

Raymond K Tang

Kuan M Lee

Nam S Wong

Jar Jar Lee

James S Ajioka

Ruey S Chu

James G Small

Richard W Burns

James V Strahan

Ruey-Shi Chu

Unmesh B Gundewar

Gordon L Howard

Donald J Gibson

Sien-chang Charles Liu

James U Clark

Joseph M Hellums

A method for automated project planning comprises displaying a list of procedure identifiers representing a plurality of procedures at a client and communicating a procedure identifier selected by a user from the client to a server. The method further comprises displaying a procedure data sheet at the client in response to the selected procedure identifier, the procedure data sheet including a list of procedure steps for the selected procedure identifier and at least one of the listed procedure steps including a template identifier. The method also comprises communicating the template identifier selected by the user from the client to the server and displaying a template at the client in response to the selected template identifier, the template including data fields for completion by the user. The method further comprises communicating the template having completed data fields from the client to the server and updating a project workspace with the completed template.

System and method for implementing project procedures

A wideband, wide angle sidelobe cancellation array system is disclosed. The system includes a main array formed of a plurality of regularly spaced elements, and an auxiliary array formed of two auxiliary antenna elements spaced from the outermost elements of the main array a distance equal to one-half the spacing of the main array elements. The received signals from the main array elements are combined to form a main array signal. The contributions from the auxiliary array elements are combined to form an auxiliary array signal. The two array signals have a good amplitude and phase match over a wide frequency and angle range. The main array and auxiliary array signals are then combined to form a system array signal wherein the sidelobe energy in the main array signal has been substantially cancelled. The system can be made an adaptive one by the addition of adaptive RF phase and amplitude weighting to the auxiliary array signal prior to combining with the main array signal.

Wideband and wide angle sidelobe cancellation technique

A multiple layer dipole array that provides for a multi-frequency band phased array antenna. Several layers of dipole pair arrays, each tuned to a different frequency band, are stacked relative to each other along the transmission/reception direction. The highest frequency array is in front of the next lowest frequency array and so forth. Due to the frequency selective property of the arrays, incident high frequency signals are completely absorbed by the highest frequency array. In regard to incident low frequency signals, the insertion loss due to higher frequency arrays is small resulting in good performance of the lower frequency arrays. The multi-frequency band phased array antenna may use active or driven dipole pairs, or parasitic elements that form the multiple layer dipoles. The multiple layer dipole array of the present invention may employ corporate feed circuit boards and a corporate feed power divider, using strip transmission line circuits, for example. The multiple layer dipole phased array of the present invention may also employ a feed-through lens arrangement to simplify the feed network.

Multi-frequency band phased-array antenna using multiple layered dipole

An ultra wideband (UWB) phased array antenna using a frequency-multiplexing, space-fed lens with a UWB feed horn achieves multi-octave bandwidth. The lens includes two UWB radiating apertures with relatively narrow band phase shifters connecting corresponding radiating elements of the arrays. Each aperture multiplexes the incoming UWB signal into separate frequency bands so that the phase shifters need only be tuned to these narrower frequency bands, and are set to form a beam in the desired direction. For wide instantaneous bandwidth operation, the beams from the various frequency bands are collimated in the same direction. For multi-mode operation, the beams corresponding to the various frequency bands are formed in different directions. The phase shifters need have a maximum phase shift of 360 degrees.

Ultra wideband phased array antenna

A millimeter wave antenna capable of electronic scanning for automobile collision avoidance radar. The antenna includes a linear ferrite loaded slot array which illuminates a dielectric lens. The antenna system has no moving parts. Beam scanning is achieved by controlling the bias magnetic field along the ferrite rod of the slot array.

Electronically scanned antenna for collision avoidance radar

An impulse radar that forms a predetermined radar pulse train in space by transmitting individual spectral components thereof. Thus, a train of extremely short pulses is obtained without switching a radio frequency signal on and off at a high rate. An oscillator is coupled to a harmonic generator, and a power divider distributes the output of the harmonic generator to a multiplicity of amplifiers. Each amplifier has a phase-locked VCO circuit that provides frequency accuracy, spectral purity, low noise and frequency stability. Thus, each amplifier provides one of the spectral components of the predetermined radar pulse train. The amplifiers are coupled to a multiplexing feed that illuminates a reflector. On receive, the multiplexing feed separates the spectral components of the incoming pulse train. Each spectral component is coupled to its own narrow band receiver, and one receiver is used to amplify and detect each spectral component. The signals from the receivers are coherently combined in a signal processor in which the signals add coherently and the noise signals do not. The output of the signal processor may be applied to a radar display. The short pulses produced by the radar provide very high resolution, and can map a target by sweeping across it, thus imaging it. The radar emits a wideband signal at a low power level; the signal is difficult to detect and intercept, and thus provides for a low probability of intercept radar. The radar may be used as a microwave link, wherein the oscillator may be frequency modulated to provide communications. It may also be used as a covert IFF system to identify friendly aircraft. The radar provides signals that penetrate sand and may be used for mapping and to locate land mines buried in the sand. It may also be used for clearing away land mines by detonating them. When the power is turned up, the radar provides for a directed energy beam. The radar may perform adaptive jamming, and is also a jam resistant radar. It is hard to jam because the receiver array is insensitive to noise at frequencies outside the narrow bandwidths of the individual receivers and also to noise which is not coherent across the multiplicity of receiver channels.

Ultra wideband radar employing synthesized short pulses

A low sidelobe, solid state array antenna apparatus comprises a large radiating aperture divided into a large number, N, of small, closely spaced radiating apertures, each small radiating aperture having associated therewith a radiating element and a linearly polarized solid state power module. The large radiating aperture is divided into M, preferably between 3 and about 10, differently sized, elliptically shaped, concentric radiating zones superimposed, for analysis purposes, upon another. Each such zone has an output voltage amplitude, E.sub.i, and semi-major and semi-minor axes of respective lengths, a.sub.i and b.sub.i, each zone being considered separately in the far field equation: ##EQU1## J.sub.1 .sup.(u i.sup.) is the first order Bessel function, a.sub..theta. and a.sub..phi. are unit vectors in the spherical coordinates and K.sub.o is the wave number associated with the radiated field. Using the far field equation, values of E.sub.i, a.sub.i and b.sub.i for each zone are computed which result in the far field sidelobe peak gain being a minimum or being a specified number of dB, for example, at least about 30 dB, below the far field mainlobe gain. The values of E.sub.i in overlapping zones are summed to establish the required voltage amplitudes of the underlying power modules associated with the N radiation apertures.

Low sidelobe solid state array antenna apparatus and process for

An apparatus and a method for enhancing the radar cross section of a target. The present invention is an impulse radar system that implements a method that comprises the following steps. A pilot impulse radar pulse is transmitted at a target. The pilot pulse comprises a plurality of individual pulses having respective distinct frequencies generated by the impulse radar system. A return pulse from the target is received by the impulse radar system and provides information indicative of target scattering centers. The return pulse is used as a calibration signal for generating a phase conjugated pulse. The phase conjugated pulse is then transmitted at the target. Processing a target return signal derived from the transmitted phase conjugated pulse enhances the radar cross section of the target because the waveform of the transmitted phase conjugated pulse is matched to the characteristics of the target. The present invention is adapted to detect low radar cross section targets without encountering the problems and frequency restrictions with conventional radar systems. In a second embodiment of the present invention, when a progressive phase variation is applied to the transmit pulses, the radar cross section contributed by backward travelling wave is made to add in phase in the received direction by processing the received target return pulses while adaptively adjusting the phase sequence of the transmitted pulses. When the appropriate phase sequence is achieved which is such that the transmitted pulses match the scattering centers on the target, then an enhanced return signal is received.

Radar cross section enhancement using phase conjugated impulse signals

A predetermined radar pulse train is formed in space by transmitting individual spectral components thereof. Thus, a train of extremely short pulses is obtained without switching a radio frequency signal on and off at a high rate. A crystal oscillator is coupled to a harmonic generator such as a comb generator. A power divider distributes the output of the harmonic generator to a multiplicity of final filter amplifiers. Each final filter amplifier has a phase-locked VCO circuit that provides frequency accuracy, spectral purity, low noise and frequency stability. Thus, each final filter amplifier provides one of the spectral components of the predetermined radar pulse train. The final filter amplifiers are coupled by duplexers to a broadband multiplexing feed such as a nested cup dipole feed that illuminates a reflector. On receive, the broadband multiplexing feed separates all the spectral components of the incoming pulse train. Each spectral component is coupled to its own narrow band receiver by the duplexers. One receiver is used to amplify and detect each spectral component. The signals from the receivers are coherently combined in a signal processor in which the signals add coherently and the noise signals do not. This provides a processing gain in signal to noise ratio corresponding to the total number of receivers. The output of the signal processor is applied to a radar display.

Ultra wideband radar transmitter employing synthesized short pulses

In a printed circuit embodiment, dielectric boards in a multilayer arrangement have their ends protruding from a ground plane. Sets of printed dipole elements are disposed along the edge of each board. Each set of dipole elements has three feed ports. Bandpass filters are provided for each feed port. Phase shifters are coupled to each of the feed ports through its respective bandpass filter. At the low band, the outer feed ports are shorted by the filters so that the two sections of dipole elements to the left of the center feed port form one lone band dipole arm, and the two sections of dipole elements to the right of the center feed port form the other low band dipole arm. The low band dipole is driven at the center feed port. At the high band, the center feed port becomes an open circuit so that the two sections to the left thereof form one high band dipole, and the two sections to the right thereof form a second high band dipole. The two outer feed ports drive the dipole array at the high band. In an MMIC embodiment, printed circuit stubs are bridged across the outer feed ports. The length of each stub is one wavelength at the low frequency band, and one-and-one-half wavelengths at the high frequency band. At the low frequency, the stubs appear to be short-circuited. At the high frequency band, the terminals of the stubs provide a 180 degree phase difference for a balun.

Multi-frequency band phased array antenna using coplanar dipole array

A module disposed at each radiating element of a phased array antenna, the module having a limiter, a low-noise amplifier and a phase shifter. One embodiment includes a DPDT switch to permit use of a common phase shifter on transmit and receive. On transmit, the DPDT switch is thrown in a position that connects the phase shifter directly to the radiating element. On receive, the DPDT switch is thrown in a position that connects the radiating element through the limiter and low noise amplifier and then to the phase shifter. Another embodiment uses a four-port circulator in place of the DPDT switch, and uses separate phase shifters for transmit and receive. A semi-active module for a constrained feed array uses both a DPDT switch and a circulator and uses a common transmit/receive phase shifter. A semi-active module for a space-fed array uses two DPDT switches, a single phase-shifter and limiter/low-noise amplifier and two antenna elements; one of receive, and one for retransmit. Another module employs a four-port circulator, separate transmit and receive phase shifters, and separate transmit and receive beamforming networks. In a monopulse radar transmitter, a module using a four-port circulator and a separate receive diode phase shifter, limiter and low-noise amplifier is used with a receive monopulse feed, transmit ferrite phase shifters and a transmit series feed.

Semi-active phased array antenna

A lens antenna having four phased array apertures positioned for hemispherical coverage is disclosed. An array of phase shifters is disclosed, each of which is interconnected with four radiating elements, one on each of the four apertures. A feed horn is used to feed the lens and switches in the lens are used to switch the energy received from the feed horn to the phase shifter, and after phase shifting, to a selected aperture for radiation. The switches also perform a reciprocal function by switching energy received at an aperture to the phase shifter and then to an aperture for radiation to the feed horn. In a further embodiment, the mounting of transmitting and receiving components, such as a high power amplifier and a low noise amplifier, with a combination of DPDT switches in the lens is disclosed and results in a solid state T/R type antenna array. In one embodiment, the switches enable the lens to radiate from three of the apertures for a scan angle of 270 degrees from a single feed horn. The addition of more feed horns per face results in multiple radiated beams from a single face.

Three dimensional feed through lens with hemispherical coverage

A dual band array antenna is disclosed having interleaved waveguide and dipole arrays, each operating in a different frequency band. The orientation of the waveguides and dipoles is such that polarization of the signals of the two frequency bands is perpendicular to each other, thus reducing mutual coupling. The waveguides are used for the higher frequency band and their cutoff frequency is selected to be above the lower frequency band at which the dipoles operate, in order to reduce mutual coupling into the waveguides. In one embodiment the dipoles are printed on a substrate having a dielectric constant selected so that dipole spacing is the same as the waveguide spacing. This eliminates grating lobe formation in the radiation pattern of the waveguide array. A low pass filter is included in the dipole feed circuit to reject the frequencies at which the waveguides operate. As a result of the invention, two beams of two different frequency bands are independently and simultaneously steerable in a single antenna aperture.

Interleaved waveguide and dipole dual band array antenna

A radiating element having a continuous aperture substantially greater than one-half the center frequency wavelength for use in an electronically scanned phased array antenna operating in the range of 94 GHz. The new radiating element comprises a ferrite block having a radiating aperture which measures 5.lambda. by 5.lambda. in contrast to the conventional discrete radiating element which measures one-half .lambda. by one-half .lambda.. Thus, where a phased array antenna comprised of an array of the new radiating elements would require only a single radiating element to fill an aperture measuring 5.lambda. by 5.lambda., a phased array antenna of conventional design would require one hundred discrete radiating elements to fill the same aperture. A tapered magnetization is applied to the continuous aperture ferrite block. Thus electromagnetic energy traveling through the block and exiting the radiating surface is phase shifted, with respect to the energy entering the block, in a similar tapered fashion. The degree of phase shift can be varied by adjusting the slope of the tapered magnetization. This permits scanning of the continuous aperture pattern. The continuous aperture subarray is specially constructed to minimize the spacing between such elements which have been assembled to form an antenna array. The ferrite block has been split into two halves, separated by a dielectric, to minimize transverse magnetization and thereby improve the characteristics of the tapered magnetization applied to the ferrite block. When a plurality of such continuous aperture subarrays is used to form an antenna array, provision is made to adjust the phase at the center of each continuous aperture subarray with respect to the phase of the adjacent subarrays, thereby allowing scanning of the entire pattern of the phased array antenna.

Continuous ferrite aperture for electronic scanning antennas

A millimeter-wave phase shifter for use at high millimeter-wave frequencies is disclosed. The phase shifter employs continuous aperture ferrite and corrugated horns to make a reciprocal phase shifter in the frequency range of interest. Applied linearly polarized energy is expanded in cross-section by means of a first corrugated horn. The expanded energy is focused by a first lens, circularly polarized and applied to a ferrite phase shifting section. The phase shift applied to the energy is controlled by means of phase control circuitry and a yoke and coil arrangement. The phase-shifted energy is then converted to linearly polarized energy by a second circular polarizer focused by a second lens and contracted in cross-section by a corrugated horn. The use of the corrugated horns, polarizers, lenses and ferrite phase shifting components allows a much larger device to be fabricated and hence physical tolerances are reduced by an order of magnitude for the frequency range of interest. In addition, both the efficiency and power handling capability are greatly improved. Both reciprocal and nonreciprocal phase shifters are disclosed.

Growing community of inventors

Chestnut Hill, MA, United States of America

Raymond K Tang