Abstract: Disclosed is an antenna in which certain radiators are shared for multiple frequency bands. The antenna may include at least one first radiator for a first frequency band; one or more second radiator for a second frequency band; and a third radiator. Here, the third radiator may be used when realizing the first frequency band and may also be used when realizing the second frequency band.

Abstract: A radar installation searches a limited volume within view, such as a covariance ellipsoid where a target is expected to be found based on a cue from a remote radar. The radar activates beams selected from an angularly diverging array of beams spanning the azimuth and elevation of an acquisition face whose area increases with range from the radar. A controller projects the search volume relative to the acquisition face, for selecting beam positions intersecting the search volume, and activates beams for a time interval that determines maximum range. A coordinate transformation is effected, so that with decreasing range, the angular divergence between projected points of the search volume is correspondingly increased, including points tangent to outer edges of the ellipsoid. The search volume accurately corresponds to the covariance ellipsoid by accounting for perspective in this way, reducing the time needed to examine the search volume for the target.

Abstract: The present invention relates to a device for realizing beam-forming in CDMA mobile telecommunication system by employing smart antenna technique and method thereof, which forms multiple fixed beams in a sector, and uses multiple fixed beams to form the traffic channel with narrow beams and the common channel with sector beams simultaneously in the same smart antenna system, and overcomes the problem of inconsistency of phrases of respective channels due to the variations of time and temperature without complicated correction technique, thereby improving the capacity and performance of CDMA system with multiple antennas.

Abstract: In the context of array sensors such as radar, sonar, and communications receiver arrays, the present invention exploits the geometry phase components of radiated wavefronts associated with the signals of interest in order to reduce the bandwidth requirements for DOA and beamforming processing. Additionally, geometry phase is exploited in order to effectively increase the resolution of an array without changing the size of its physical footprint or the number of array elements. Other embodiments of the invention include the use of virtual array elements for increase in effective array size.

Abstract: A power gated variable hop cycle beam laydown (700) manifests itself as first cells (C, D) supported by a first hop cycle, second cells (G, H) supported by a second hop cycle, and transition cells (E, F) supported by a transition hop cycle. The transition hop cycle uses power gating to transition the laydown (700) from cells (C, D) operating at the first hop cycle to cells (G, H) operating at the second hop cycle. To this end, the transition hop cycle power gates its downlink beam for a portion of time needed to reduce interference between nearby (e.g., adjacent) cells.

Abstract: A feeding method and device, particularly for a Doppler VOR system, and to a Doppler VOR system using such a feeding device. The feeding method performs a blending function, which is an approximation of the sinX/X function limitedly to the three central lobes, and is obtained by amplitude overmodulation of a single signal according to a periodic function. The blending function can be controlled through the control of the periodic function.

Abstract: A retransmitted Ground Positioning System (GPS) using retransmission of a GPS signal in combination with an interferometer for determining the angular deviations of an aircraft relative to a landing site in both vertical and horizontal planes, by using the accumulated phase of the GPS carrier signal. The system includes an aircraft and a landing site, wherein a first unit comprising one of the aircraft and the landing site includes a GPS retransmitter for retransmitting GPS signals to a second unit comprising the other of the aircraft and the landing site, which includes a GPS receiver/computer two spaced apart GPS antennas mounted on a rotating frame, the plane of rotation of which is normal to the landing strip. In a first general configuration, each GPS antenna in the interferometer comprises a GPS receiving antenna and a GPS transmitting antenna, and an amplifier connecting the GPS receiving antenna with the GPS transmitting antenna, and the aircraft includes a GPS receiver/computer.

Abstract: Linear array antenna systems are used in X-scan aircraft location systems and methods able to avoid disabling azimuth error conditions caused by multipath reflections under roll and pitch conditions during aircraft carrier landing operations. Aircraft azimuth and elevation data is derived based upon time of incidence at an aircraft location of two transverse, diagonally oriented, scanned antenna beams. The aircraft location data is derived by comparing time of incidence data with data on known timing of scanning of the beams, which have diagonally-oriented fan beam patterns. A plurality of vertically oriented radiating elements are typically positioned along a line diagonal to the vertical to produce a diagonally oriented fan beam pattern. Beam scanning results from relative adjustment of signal portions supplied to the radiating elements.

Abstract: In contrast with conventional transmitting stations for a position locating system in which the main equipment and the standby equipment operate alternately and are monitored by checking the transmitted signal received from external sensors, the present invention monitors at least the standby equipment during inactive periods during which no signal is being transmitted. In a preferred embodiment, external sensors (FS, MF) are provided for monitoring both the main transmitter (TXM) and the main timing and control section TCS1) during transmission periods, a dummy load (DL) and an internal sensor (IS) is used for monitoring the standby transmitter (TXR) during non-transmission periods, internal monitoring information (MI) is used for monitoring the reserve timing and control section (TCS2) and the electronic antenna (EA), and the two monitor sections (MS1, MS2) contained in the monitor unit are used to monitor each other.

Abstract: A passive surveillance method and system, capable of operation in conjunction with both non synchronous and synchronous pulse pattern rotating ground radars. Received signal scan modulated pulses are deinterleaved and correlated with a previously selected repetitive portion of an interrogation signal source base pulse pattern. A single receiver channel, sequential lobe on receive only (LORO) direction finding antenna is employed in the system to modulate received signals to extract target object relative bearings for the correlated signals. The system makes use of all available data to determine the best estimate of the target object position.

Abstract: Airborne navigation receivers are designed to derive navigation information with accuracy immune to beam asymmetry errors. Scanned navigation beams of the Microwave Landing System are subject to asymmetry causing beam center measurement errors at power levels other than a standard level 3dB down from peak. Dwell gate and split gate type receivers achieve error immunity through offsetting of errors at power levels above and below a standard power level.

Abstract: The object of this invention is to reduce the adverse system performance effects resulting from antenna pattern sidelobes. It has particular application to the time reference scanning beam of the international microwave landing system (MLS) where sidelobe energy reflecting into the mainbeam at the receiver antenna introduces a timing measurement error. It also has application to systems such as height finding radar where signals entering through antenna pattern sidelobes degrade system performance. This invention describes methods and apparatus for system performance enhancement through the application of sidelobe amplitude and phase control.

Abstract: In a Microwave Landing System (MLS) transmitting landing guidance signals and data signals according to a time division multiplex signal format, a method and means for replacing faulty primary equipment with standby equipment. Redundant electronics units are provided for generating guidance and data signals. Transfer control means connect alternate ones of the electronics units to the appropriate antenna of the system such that no two consecutive transmissions of the same guidance or data signal is made by the same electronics unit. The signals transmitted by the system are monitored for accuracy and conformity to the signal format. If a fault is detected in a monitored signal, the electronics unit responsible for generating the faulty signal is no longer used and system operation continues with non-faulty units, unless the faulty detected indicates antenna misalignment. If antenna misalignment occurs, system operations are halted.

Abstract: Microwave landing systems are used to enable aircraft to make landings even in poor visibility. One distinguishes three categories of approach and landing manoeuvers. Of particular importance are Category III operations, i.e., those in which the pilot depends exclusively on the navigation system, because he cannot see the runway. Throughout a Category III landing operation, it must be ensured that the navigation system does not fail, and that the information contained in the signals being radiated by the navigation system is reliable. To that end, two executive monitors are arranged such that the first to detect a signal error functions as a master monitor. If the slave monitor then detects (within a reduced error threshold) the same signal error, an error in the system being monitored is confirmed and appropriate safety measures are taken (e.g. immediate changeover from the faulty transmitter).

Abstract: A multipurpose system provides radar surveillance for air traffic control purposes. The system includes four separate active phased-array antennas, each with .+-.45.degree. coverage in azimuth, from 0.degree. to 60.degree. in elevation. Each antenna element of each phased-array antenna is coupled by a low-loss path to the solid-state amplifier associated with a transmit-receive (TR) module. Each antenna produces a sequence of pencil beams, which requires less transmitted power from the TR modules than a fan beam, but requires more time because the pencil beam must be sequenced to cover the same volume as the fan beam. In order to scan the volume in a short time, the PRF is responsive to the elevation angle of the beam, so higher elevation angles use a higher PRF. Low elevation angle beams receive long transmitter pulses for high power, and pulse compression is used to restore range resolution, but the long pulse results in a large minimum range within which targets cannot be detected.

Abstract: In the ground-based equipment of a microwave landing system (MLS), a linear array antenna is employed to generate both a scanning guidance beam, which provides azimuthal position data to an incoming aircraft, and a pair of out-of-coverage indication (OCI) beams, which are disposed outside of the sector covered by the scanning guidance beam. For sweeping the guide beam, phase shifts are updated in a linear phase gradient to scan the beam to the right and to the left of the centerline of the antenna. To form the pair of OCI beams, the main lobe of the antenna radiation pattern is directed to one side of the antenna's centerline, outside the normal scanning range, thereby producing a grating lobe on the opposite side of the centerline. Furthermore, a quadratic phase shift function is superimposed upon the linear phase gradient to defocus the OCI beams so as to fill a sufficient sector of space, on both sides of the scanned region, for OCI coverage.

Abstract: There is disclosed a microwave landing system wherein there are provided at least two means which are spaced by a predetermined distance and from two of which beams radiate alternately to scan a predetermined region vertically and horizontally. In the microwave landing system, multipath propagating beams due to the scanning beams or side-lobes thereof are of out of phase or in non-correlation with each other in a receiving means in an aircraft to suppress multipath errors.

Abstract: Guidance equipment for a microwave landing system has an azimuth guidance device and an elevation guidance device for providing angle information constructed into a single assembly. The selective formation of an azimuth scanning beam and an elevation scanning beam and the transmission of preamble signals are implemented by a single circuitry.

Abstract: A microwave landing system in which a beam scanning antenna is provided with an amplifying function to constitute an active array, a traditional power amplifier and the like are omitted to enhance the reliability of operation. The outputs of phase shifters each being associated with a respective one of radiating elements are connected to 1/2 dividers each having p-i-n diodes at opposite output terminals thereof, and the p-i-n diodes of each 1/2 divider are turned on and off alternately. Output signals are fed to radiating elements and a multiplexer with a minimum of loss.

Abstract: An MLS system having redundant subsystems. Dual signal sources feed dual power dividers. A first switch array selects the power divider to be used and provides the selected signals to an array of phase shifters. A second switch array provides the phase shifted signal, which may be amplified, to either a primary array having elements for radiating a scanning beam or a recombining network having outputs connected to auxiliary antennas. A third switch array provides control signals to the array of phase shifters from either a main beam steering unit or a standby beam steering unit. Alternatively, the dual signal sources feed a single power divider through a circulator. Duplicate auxiliary antennas may be used with antenna switches located before the power dividers or circulator for selectively providing the signals to the auxiliary antennas instead of the primary array.

Abstract: The fault monitoring function of an executive monitor contained in a microwave landing system is verified by evaluating a history of the parametric information sampled by an executive monitor and storing in memory the number of out of tolerance parametric signals received from an antenna means over a predetermined time period, replacing the stored number of out-of-tolerance parametric signals with a predetermined number that will be beyond a second predetermined limit if another out-of-tolerance parametric signal is added to said number, adding one such internally generated out-of-tolerance parametric signal to said predetermined number, generating an alarm if said sum is beyond the second predetermined limit, and restoring the previously stored number of out-of-tolerance parametric signals received from the antenna means if the alarm was generated, and shutting the system down if an alarm was not generated.

Abstract: A scanning beam transmit antenna system includes a source of electromagnetic energy, radiating elements and a feed network connecting the source to the radiating elements. A beam steerer controls the phase of the electromagnetic energy at each of the radiating elements. Power dividers route the electromagnetic energy to each of the radiating elements, and switches control the flow of the electromagnetic energy among the power dividers. The beam steerer changes the phases of the energy emitted by the radiating elements as a function of time to cause sequentially a motion of the scanning beam in the "TO" direction and a motion of the scanning beam in the "FRO" direction, and the switches modify the flow of the electromagnetic energy through the power dividers to and among the radiating elements on one half of the linear array during the "TO" motion of the scanning beam and to the radiating elements on the other half of the linear array during the "FRO" motion of the scanning beam.

Abstract: Successive MLS scanning signals are received as pulse-type analog signals and converted into corresponding digital signals. The centroid of each digital signal is determined at at least two different levels below the peak of the digital signal. The centroids for each signal are averaged, whereby the average represents the centroid of the corresponding received pulse-type signal.

Abstract: A guidance system for aircraft wherein a radio antenna on the ground transmits a beam that sweeps across an aircraft and the aircraft receives the beam and utilizes its amplitude waveform in determining the location of the aircraft from the station. At low elevation angles of the aircraft the portion of received waveform that includes significant amounts of signal reflected from the ground is used in only a preliminary manner. The more reliable, directly radiated, portions of the waveform are utilized to compute by least squares error, the median of a Gaussian beam shape. That median serves as an estimate of the time that the transmitting antenna was pointing directly at the aircraft.

Abstract: In the basic configuration of the microwave landing system, an azimuth station (2) and an elevation station (1) are interconnected by a data link for transferring data and sync signals, and each of the stations includes a monitoring facility (10, 15; 3, 8) for monitoring its signals in the near field. In the novel microwave landing system, the near-field monitoring facility of one of the stations is also used to monitor the signals from the other station in the far-field.

Abstract: A method and device for monitoring a station in a landing aid system of the MLS type comprising two transmission assemblies. Transmission from the electronic sweep antenna is provided alternately by said two transmission assemblies, the operation thereof being permanently tested and switching thereof being performed as a consequence.

Abstract: The invention provides independent guidance and monitoring integrated into an MLS landing system and a scaled-down MLS take-off or missed approach guidance system useable at small airports. An added fixed beam precision guidance system is integrated into the MLS time sequence format. The fixed beam guidance system is based upon the concept of using paired fixed overlapping beams, sequentially radiated by different fixed antennas (80 and 81), oriented to left and right of a prescribed guidance path. The paired beams overlap at the prescribed guidance path in such a manner that an aircraft departing or making a missed approach on such path will intercept equal signal intensities to indicate an on-course condition.

Abstract: A scanning system for a phased array antenna for operation at a selected frequency between a first frequency and a second frequency includes the storage of phase shift command signals for each of the phase shifters coupled to radiating elements of the antenna. The memory which stores the phase shift commands is addressed sequentially to provide for a step-wise scanning of a beam of radiant energy at a first frequency of the antenna. The addressing is accomplished by incrementing a count resulting from a counting of clock pulses. Compensation for the stepped positions of the beam for the difference between the selected frequency and the first frequency is accomplished by altering the number of pulses which increment the count of the addressing. The altering is accomplished by the storing of sequences of clock pulses at varying temporal spacings which are used for gating out selected ones of the incrementing pulses.

Abstract: The invention provides independent guidance and monitoring to be integrated into an MLS landing system and also provides a scaled-down MLS landing guidance system useable at small airports. In both cases an added fixed beam precision guidance system is integrated into the MLS time sequence format. The fixed beam guidance system is based upon the concept of using paired fixed overlapping beams, sequentially radiated by different fixed antennas. One pair is oriented to left and right of the centerline of the runway, and the other pair is oriented above and below the desired glideslope. The first set of paired beams overlap at the centerline of the runway in such a manner that an aircraft approaching exactly on centerline will intercept equal signal intensities to indicate an on-course approach.

Abstract: The invention provides independent guidance and monitoring to be integrated into an MLS landing system and also provides a scaled-down MLS landing guidance system useable at small airports. In both cases an added fixed beam precision guidance system is integrated into the MLS time sequence format. The fixed beam guidance system is based upon the concept of using paired fixed overlapping beams, sequentially radiated by different fixed antennas. One pair is oriented to left and right of the centerline of the runway, and the other pair is oriented above and below the desired glideslope. The first set of paired beams overlap at the centerline of the runway in such a manner that an aircraft approaching exactly on centerline will intercept equal signal intensities to indicate an on-course approach.