Abstract: A self-pointing antenna has a reflector, a feed or a sub-reflector and a plurality of support struts coupled between the reflector and the boom arm and supporting the feed or sub-reflector. At least one actuator is operatively coupled with the support struts for adjusting the position of the feed or sub-reflector relative to the reflector so as to selectively adjust either/or both of the beam elevation and azimuth of a main beam axis of the antenna.

Abstract: When a converter 14 is rotated via a rotation mechanism 17, the arrangement inclination angle of two primary radiators 15a and 15b can be adjusted in the range of 0 to 20 deg. with respect to an axis which is in parallel with the ground. Also the reception polarization angle due to probes of the primary radiators 15a and 15b can be adjusted in the range of 0 to 20 deg. while maintaining a preset difference in polarization angle among the satellites. Therefore, the arrangement inclination angle of the primary radiators 15a and 15b for respectively receiving signals from the two satellites, and the reception polarization angle in the primary radiators 15a and 15b can be simultaneously easily adjusted by rotating the converter 14 via the rotation mechanism 17.

Abstract: A beam forming low profile scanning antenna system is provided comprising a radiating element (11)for radiating signals and a pair of panels (13 and 15) each having an array of phase-inducing transmitting resonant elements (21) on a pair of panels for focusing said radiating signals to produce radiated beams. The panels are rotated with respect to each other (17) to scan said beams.

Abstract: A reflector antenna is disclosed with a stator portion and a rotor portion which is supported for rotation relative to the stator portion about a rotation axis. A reflector that is connected by an electrical connection with the stator portion, is secured to the rotor portion. The electrical connection is formed as a flexible connecting cable, wherein one end of the cable is attached to the rotor portion and the other end is attached to the stator portion. A segment of the connecting cable rotates with half the rotation speed of the rotor portion and with the same rotation direction as the rotor portion.

Abstract: Variable beamwidth antenna systems for use on spacecraft that is capable of changing their beamwidths while the spacecraft in on orbit. The variable beamwidth antenna systems include a main reflector, a subreflector, a feed horn, a main reflector displacement mechanism and a feed horn (or subreflector) displacement mechanism. For broaden the beamwidth, the RF feed horn and the subreflector are moved close together by proper distance. The main reflector is moved away from the subreflector along a line through centers of their respective surface by a distance given by a predetermined equation. Another embodiment of the present invention provides for a zoom contour beam antenna system that radiates a contour beam and whose beam is variable or zoomable.

Abstract: Antennas with steerable antenna patterns and techniques for using such antennas are described. In accordance with the invention, antenna patterns with one or more NULLs are used. Through the use of digital control signals the antenna pattern is steered so that a source of signal interference, e.g., a multipath signal, will be located in a NULL. In this manner the received signal's S/N ratio can be maximized thereby facilitating demodulation. The techniques of the invention can be applied to television, computer devices, mobile devices and a wide range of other systems. Digital commands to control an antenna may include multiple information fields, e.g., a direction field, a channel field, a gain field and a polarity field. Antennas incapable of supporting the specified fields disregard information in fields which are not supported. Information in each supported field is decoded and used to adjust the corresponding antenna characteristic.

Abstract: An antenna includes a lower plate assembly having at least one antenna port and including a beamformer which provides a uniform excitation on the first surface of the lower plate assembly in response to a signal fed to the at least one antenna port and an upper plate having a radiating aperture, the upper plate movably disposed on the first surface of the lower plate assembly to couple energy from the beamformer in the lower plate assembly to a plurality of radiating elements, wherein the position of the upper plate relative to the lower plate determines a scan angle of the antenna.

Abstract: A radar antenna with a parabolic reflector having a combined polarization twist reflecting unit and a plane reflector that reflects and transmits radio waves according to their polarized direction and with the plane reflector disposed outside. The plane reflector is integral with the case of the antenna and is disposed at a position that is approximately half of the distance from the parabolic reflector to the focal point of the parabolic reflector. Additionally, a primary radiator is disposed at a center position of the parabolic reflector and at a distance for the plane reflector that is approximately a distance from the plane reflector to the focal point of the plane reflector.

Abstract: A telecommunications system antenna for communicating, in transmission and in reception, with a large area whose position relative to the antenna varies. The antenna has motors (80, 82) for pointing the antenna towards the area and radiating elements (74, 76) associated with a control device for modifying the antenna's radiation pattern according to the relative position of the antenna and the area. When the antenna is installed on a telecommunications satellite, as the antenna moves, the antenna can remain constantly in communication with an area of the Earth covering several hundred kilometers.

Abstract: A method and a device is disclosed for the generation of a lens device including a plate of ferroelectric material, the transmission phase gradient of which is be varied over the lens by means of a controllable static electric field. The division of an aperture will depend on the number of degrees of freedom to be controlled simultaneously. According to the present invention an electromagnetically transparent highly resistive film (24, 34) is applied at both sides of a plate presenting ferroelectric properties. At two opposite edges of these resistive films highly conducting wires (22, 23 and 32, 33) are applied and electrically connected along the resistive film. The pairs of highly conductive wires at the opposite edges of each one of the two films on the plate presenting the ferroelectric properties are running perpendicular to each other.

Abstract: An antenna comprising a feed for delivering electromagnetic energy to a rotatable combination of a dielectric lens and a reflective surface. The combination of the dielectric lens and the reflective surface is placed proximate to and in front of an energy feed, such as a horn, to support the scanning of an antenna beam in response to rotation of the lens/reflective surface assembly. The lens typically comprises a dielectric material and the reflective surface can comprise a thin layer of material operable to reflect electromagnetic energy. For example, the lens can comprise a half-cylinder shape of dielectric material and the reflective surface can be applied to the flat portion of the half-cylindrical lens. Alternatively, the antenna can comprise two or more electromagnetic feeds and a cylindrical lens of dielectric material including a centrally-embedded, two-sided reflective surface.

Abstract: A system and method for automatically positioning/directing satellite antennas towards a satellite with which it is to communicate. The system and method may use characteristics of symmetry of mutually exclusive orthogonal axes. By using the symmetry of the antenna main beams, the ideal direction of the antenna can be attained and, at the same time, maximum cross-polarization may be achieved. The cross polarization may be required in order not to interfere with the orthogonal polarization. The system and method may position the Antenna on three mutually exclusive orthogonal planes, including the azimuth plane, the elevation plane, and the polarization plane. The system and method may include an indoor unit, which may include a satellite receiver, a telemetric transmission, and supply of voltage to a control system and which may control a drive motor and/or an electronic search device; and an outdoor unit, which may include a supervisory unit, a motor, and a control unit.

Abstract: A ground penetrating antenna apparatus and method are provided for locating underground objects via radar, sonar, or similar methods. The apparatus includes one or more antennas that are rotatably affixed to support extensions that also rotate, but about an axis that is different from each of the antenna axes. The apparatus includes a linear propulsion mechanism, and the support extensions may be coupled to the linear propulsion mechanism via a transmission mechanism. In one embodiment, the supporting extensions rotate at a constant rate and each antenna rotates at that same constant rate but in the opposite direction.

Abstract: A gimbal system is used for supporting and enabling the orientation of a circular satellite antenna dish in azimuth and elevation. The gimbal system includes a hoop structure, the ends of which are connected to the antenna dish. The dish is pivotally supported on the hoop structure for pivotal motion about its “X” axis. The hoop structure is mounted for rotation about the “Y” axis of the dish. The central axis of the hoop is coincidental with the central axis of the antenna. The hoop is driven by means of a motor to rotate the hoop and the antenna dish along therewith between a first position whereat the “Y” axis of the antenna is in its normal initial at rest(Y axis zero position) and a second position wherein the “Y” axis is rotated approximately eighty degrees from this initial position. A second motor is coupled to the antenna at one of the ends of the hoop structure to drive the dish about its “X” axis.

Abstract: The invention relates to a system of antennas for tracking nonsynchronous satellites (21, 22) along predefined trajectories. It is characterized in that the said system includes at least first (11) and second (12) transmitter/receiver elements moving in the vicinity of the focusing surface of the system (1) along a line of focal points, the first element (11) actively tracking a first satellite (21) and the second element (12) standing by to actively track a second satellite (22). Particular application to the tracking of nonsynchronous satellites, in particular low- and mid-orbit satellites, and of geostationary satellites.

Abstract: A system and method for positioning an electronically scanned, phased array antenna disposed on a moving platform, such as an aircraft, to enable the antenna to remain pointed at, and track, a geostationary satellite as the moving platform is in motion. The antenna is mounted on a support which is coupled to an output shaft of a motor. The motor is used to rotate the support, and therefore the antenna, as needed to maintain the beam of the antenna directed at the satellite. The support is rotated only after a scan angle of the beam of the antenna exceeds a predetermined maximum scan angle. The degree of rotational movement of the support is further selected to be such that only a minimum number of adjustments to the position of the support are needed to maintain the scan angle of the beam of the antenna within the desired maximum scan angle over a large distance of travel of the aircraft.

Abstract: A polarization twist, space-fed, E-scan planar phased array antenna. The phased array antenna incorporates a polarization twist, space-fed architecture. A plurality of unit cells are formed wherein each cell incorporates a large plurality of phased array elements and associated phase shifters. The space-feed architecture enables 2-bit phase shifters to be employed while still producing low antenna sidelobes. The phased array elements, phase shifters, and associated control circuits for controlling the phase shifters are all preferably formed on one surface of a MMIC substrate. This further simplifies significantly the cost and complexity of manufacturing and testing the E-scan phased array antenna. The antenna can therefore be used in applications where an E-scan phased array antenna would have been too costly to employ.

Abstract: An antenna control system enabling the remote variation of antenna beam tilt. A drive means (5, 30) continuously adjusts phase shifters (1, 2, 3; 36, 39, 40) feed distribution network to radiating elements to continuously vary antenna beam tilt. A controller (80) enables the beam tilt of a number of antenna at a site to be remotely varied.

Abstract: A method and a device are disclosed for the generation of a surface, the reflection phase gradient of which will be varied by means of a controllable static electric field. The present solution takes into account, instead of mainly the transmissive properties, also the reflection properties of an arrangement comprising a ferroelectric material. Such a reflecting surface may contribute to an entire antenna aperture, a portion of an antenna aperture or an element in a conventional array aperture. In a general case N lobes and M nulls are to be controlled at the same time. In such a case the surface will preferably be designed as a curved surface, for instance a rotation symmetric parabola, while in other cases the reflector element may be designed just as a plane mirror. An antenna comprising such a reflector element of ferroelectric material can also form a polarization twisting Cassegrain antenna with a flat or curved main reflector element.

Abstract: The invention relates to an antenna system for motor vehicles. This system allows mobile reception of television and radio broadcasts and of data of geostationary satellites independently of the operating condition of the vehicle. The system is for an antenna arrangement for the frequency range greater than 10 Ghz with quasi-omni-radiation in the horizontal direction.

Abstract: A method and a device are disclosed for the generation of a surface, the reflection phase gradient or transmission phase gradient of which will be varied by means of a controllable static electric field. The present solution takes into account, instead of mainly the transmissive properties, also the reflection properties of an arrangement comprising a ferroelectric material. Such a reflecting surface may contribute to an entire antenna aperture, a portion of an antenna aperture or an element in a conventional array aperture. In a general case N lobes and M nulls are to be controlled at the same time. In such case the surface will preferably be designed as a curved surface, for instance a rotation symmetric parabola, while in other cases the reflector element may be designed just as a plane mirror. An antenna comprising such a reflector element of ferroelectric material can also form a polarization twisting Cassegrain antenna with a flat or curved main reflector element.

Abstract: An antenna (1) having an EM feed (6), a rear parabolic twist reflector (3) and a front transreflector (2). The transreflector is closer to the parabolic twist reflector than the focal point of the parabolic twist reflector, and the twist reflector is defined, mounted, or otherwise formed on a parabolic surface (17) of a base (13). The base is dimensioned and arranged to provide a foundation aligning an axis of the parabolic twist reflector with an axis of the antenna, and is further dimensioned and arranged to maintain substantial alignment of the feed and twist reflector with variations in ambient temperature that would otherwise produce at least one of warping and misalignment of the parabolic twist reflector in the absence of the base.

Abstract: At least one antenna is supported on a fixed supporting portion by an oscillating mechanism having rotational degrees of freedom on a X-Y plane, and a drive mechanism such as a drive motor is arranged in the vicinity of the oscillating center axis whereby the elevation angle and the azimuth angle of the antenna can be controlled.

Abstract: In an adaptive antenna device having directivity pattern generators operable in accordance with different algorithms, respectively, in a baseband modem, beam steering processing, null steering processing, and estimating processing of an arrival direction are executed in parallel to one anther. Parameters resulting from the beam and the null steering processing are controlled by processing results of the estimating processing and are weighted and combined to individually generate directivity patterns based on the different algorithms.

Abstract: A Luneberg lens has a plurality of feeds arranged to send and receive signals to and from a plurality of satellites. The lens is spherical and is fixedly supported on a support mount. Also supported on this mount are a plurality of arcuate positioner tracks which form arcs parallel to the surface of the lens. Each of the feeds is mounted on a separate one of these tracks. The tracks are supported on the mount for separate pivotal motion along separate paths equidistant from the surface of the lens about a “y” axis relative to the lens. A motor is coupled to the drive of each of the tracks to pivotally drive its associated track in response to control signals. The feeds are mounted on the tracks for motion in paths about an “x” axis relative to the lens, such paths being equidistant from the surface of such lens. A motor drives each of the feeds in response to control signals along separate paths parallel to the lens surface.

Abstract: An antenna system having a rotatable and scannable reconfigurable shaped reflector with a movable feed system. The antenna system allows beam shapes to be rotated about an optimum axis and defocused while a spacecraft is in orbit in order to change a particular coverage pattern for the spacecraft.

Abstract: An antenna (30) includes a gimbal structure (32) having a base (46) and first and second pivoting devices (52, 54) defining a first rotational axis (40). A reflector (36) is mounted to the pivoting devices for rotating about the first axis. Signals are routed from the base to a connector (68) mounted to the reflector with a cable (10) which is coiled around a second rotational axis (50) of the antenna.

Abstract: Scanning apparatus which scans input radiation from a scene and output radiation is transmitted to a receiver system, for example a millimetre wave imaging camera or a radar receiver by a rotatable reflective plate having an axis of rotation passing through the centre of its surface, secondary reflector and static reflector, wherein the secondary reflector is a second rotatable reflective plate having a common axis of rotation with the first rotatable reflective plate, wherein the common axis of rotation is inclined at a non-zero zero angle &thgr;b to the normal to the second reflective plate. The normal to the first rotatable plate is inclined at a small angle to the common axis of rotation, typically a few degrees and forms the secondary reflector. The static reflector may be a polarising roof reflector through which radiation is input to and output from the apparatus. The apparatus also includes a 45° Faraday rotator or a birefringent surface such as a Meander-line.

Abstract: This invention is to provide an angle adjusting mechanism for an antenna to be used to connect between an antenna and its casing. The angle adjusting mechanism includes a casing provided with a pivoting recess, an antenna provided with a connecting sleeve, and a linking member which has a hollow body and a first, second and third pivoting sleeves formed in T-shape. The first pivoting sleeve is pivotably connected to the connecting sleeve of the antenna; the second and third pivoting sleeves are pivotably connected to the pivoting portion of the casing. The characteristics of this is that each of the first, second, and third pivoting sleeves of the linking member is provided with a slotted or split free end and a resilient tab through which to achieve an resilient design.

Abstract: An antenna arrangement is provided for use in a vehicle. It comprised an antenna element (601-606, 701a-704f, 901-907, 1203) and means (600, 801, 802, 803, 804, 900, 910, 1200, 1201, 1202) for moving the antenna element in relation to the vehicle. The means for moving the antenna element are arranged to move the antenna element in relation to the vehicle into a direction which is opposite to a direction of movement of the vehicle.

Abstract: A microwave antenna and light tracking system includes a microwave antenna, a microwave source, a light sensor, and a beam-guide system. The beam-guide system has a mirror set with at least one guide microwave mirror operable to guide a microwave beam along a first portion of a microwave path toward the antenna. Each microwave mirror has embedded therein a light mirror positioned to direct a light beam along a first portion of a light path substantially coincident with the first portion of the microwave path but in a reverse direction from the antenna. The beam-guide system further includes a dichroic beam splitter including a dichroic beam splitter microwave mirror having a light-transparent window therethrough. The dichroic beam splitter is disposed in a second portion of the microwave path between the mirror set and the microwave transmit/receive device and in a second portion of the light path between the mirror set and the light sensor.

Abstract: A hinged electronic device (1, 1′, 1″) comprising a base part (2), hinges (6, 6′) and a cover part (3), the cover part (3) being arranged rotatably with relation to the base part (2) about the rotation axis (7) of the hinges (6, 6′). The device (1, 1′, 1″) also comprises at least one antenna structure (9, 9′, 9″) to which is arranged an antenna (10, 18, 21) and which is arranged substantially concentrically with the rotation axis (7) of the hinges (6, 6′). (FIG.

Abstract: The Microwave Hematoma Detector is a non-invasive device designed to detect and localize blood pooling and clots near the outer surface of the body. While being geared towards finding sub-dural and epi-dural hematomas, the device can be used to detect blood pooling anywhere near the surface of the body. Modified versions of the device can also detect pneumothorax, organ hemorrhage, atherosclerotic plaque in the carotid arteries, evaluate perfusion (blood flow) at or near the body surface, body tissue damage at or near the surface (especially for burn assessment) and be used in a number of NDE applications. The device is based on low power pulsed microwave technology combined with a specialized antenna, signal processing/recognition algorithms and a disposable cap worn by the patient which will facilitate accurate mapping of the brain and proper function of the instrument.

Abstract: The invention concerns an antenna system including at least two antennas (10, 11), each of said antennas (10, 11) being capable of pointing independently of the other(s) in any direction within a solid angle. According to the invention, the antennas (10, 11) are mounted on a common support (17) co-operating with rotation means (18) for rotating the common support (17), the rotation means (18) being activated to prevent masking of one of the antennas (10, 11) by another of the antennas (10, 11). The invention applies in particular to tracking non-geostationary satellites.

Abstract: The radio area to be covered by the stationary radio transmission/reception device, for example of the base station of a cordless telephone, is illuminated by two or more directional antennas (3, 4) respectively covering a radio sub-area thereof, whereby that respective directional antenna in whose radio sub-area the mobile radio transmission/reception means, i.e., for example, the mobile part of the cordless telephone, is located is activated (antenna diversity). The method and apparatus can be advantageously utilized in cordless telephones.

Abstract: An antenna assembly for forming and directing a transmit beam, and for controlling receive and transmit beam tracking of a spacecraft in the presence of planetary aberration. The assembly includes a main reflector, a sub-reflector centered along an optical axis of the main reflector, and a moveable transmit feed for directing electromagnetic radiation along a longitudinal axis thereof. The assembly also includes an intermediate beam waveguide assembly arranged between the moveable transmit feed and the main reflector, wherein the intermediate beam waveguide assembly includes fixed and moveable optical components for guiding electromagnetic beam energy between the moveable transmit feed and the main reflector. A beam steering mechanism is coupled with the moveable transmit feed for angularly displacing the transmit beam from the optical axis by displacing the moveable transmit feed in a direction substantially orthogonal to the longitudinal axis of the transmit feed.

Abstract: A method and apparatus for training a receiver on a source are provided. The receiver is an antenna and the source is a broadcast satellite. A first signal sensor receives at least one signal from the source. The first signal sensor may be a first low noise block (LNB) downconverter of the antenna. At least one secondary signal sensor measures a strength of the received signal. The secondary signal sensor comprises four LNB downconverters, wherein each of the four LNB downconverters are located on each of four sides of the first signal sensor. The measured strength of the received signal is used to provide guidance information for training the receiver on the source. When the broadcast satellite moves relative to the antenna, the secondary LNB downconverters detect a variance in the measured strength of the at least one signal and provide guidance information based on the detected variance, thereby reducing the training time for the antenna.

Abstract: An aircraft in-flight entertainment system includes an antenna, a satellite TV receiver connected to the antenna, at least one video display connected to the satellite TV receiver, and wherein the antenna is steered using received signals from the relatively wide bandwidth from at least one satellite TV transponder, such as a direct broadcast satellite (DBS) transponder. The system may include an antenna steering positioner connected to the antenna, and an antenna steering controller comprising the received signal detector for generating a received signal strength feedback signal based upon signals from the at least one satellite TV transponder. A processor may be connected to the detector for controlling the antenna steering positioner during aircraft flight and based upon the received signal strength feedback signal. The antenna steering controller may further comprise at least one inertial rate sensor, and the processor may calibrate the sensor based upon the received signal strength feedback signal.

Abstract: A low-cost spherical reflector and a mechanically scanned antenna system utilizing such reflectors. The system employs one or more (substantially similar) primary spherical reflectors (each a truncated spherical surface), each having an associated moveable feed driven by a two-axis positioner mechanism that has few moving parts. The feed structure may preferably comprise a point source waveguide feed in combination with a shaped concave secondary reflector used in a Gregorian-like configuration to correct for spherical phase error. The positioner mechanism moves the waveguide feed and secondary reflector in tandem to shift the position of the far field beam direction in the sky. After phase correction by the secondary reflector, the resultant signal reflected from the primary aperture can simultaneously transmit and receive at two or more independent frequencies.

Abstract: A positioner (or gimbal assembly) for a compact antenna assembly is disclosed. The positioner provides accurate pointing of the antenna assembly (typically a narrow beam radio frequency (RF) radiating assembly) mounted on a rapidly moving platform. The positioner is comprised of a first, second, and third axis assemblies which support the antenna assembly and allow rotation of the antenna assembly about first, second, and third axis. The axis assemblies are arranged so the first, second and third axis are non-orthogonal and intersect at the approximate geometric center of the antenna assembly allowing continuous and independent rotation of the antenna assembly about each axis within a confined volume.

Abstract: An antenna control system enabling the remote variation of antenna beam tilt. A drive means (5, 30) continuously adjusts phase shifters (1, 2, 3; 36, 39, 40) of a feed distribution network to radiating elements to continuously vary antenna beam tilt. A controller (80) enables the beam tilt of a number of antenna at a site to be remotely varied.

Abstract: Variable beamwidth antenna systems for use on spacecraft that is capable of changing their beamwidths while the spacecraft in on orbit. The variable beamwidth antenna systems include a main reflector, a subreflector, a feed horn, a main reflector displacement mechanism and a feed horn (or subreflector) displacement mechanism. For broaden the beamwidth, the RF feed horn and the subreflector are moved close together by proper distance. The main reflector is moved away from the subreflector along a line through centers of their respective surface by a distance given by a predetermined equation.

Abstract: An antenna positioner control system and related method is disclosed. The antenna positioner control system includes a housing and a hub mounted within a housing. A support plate is rotatably mounted on the hub. An antenna is pivotally mounted on the support plate. At least one elevation drive servomotor is mounted on the support plate and interconnects the antenna for pivoting the antenna a predetermined angle and adjusting elevation of the antenna. At least one azimuth drive servomotor is mounted on the support plate and interconnects the antenna for rotating the support plate relative to the hub a predetermined arcuate distance for adjusting azimuth of the antenna. An antenna control unit is operatively connected to the elevation drive servomotor and azimuth drive servomotor and includes an elevation control circuit and azimuth control circuit.

Abstract: A device for positioning an antenna on a vehicle. The device includes a first motor-driven timing belt connected to opposite sides of the antenna frame for rotating the antenna about its elevational axis. A constant force spring or a cam compensates for changes in belt path geometry as the antenna rotates. A second motor-driven timing belt is wrapped around a perimeter of a base plate for rotating the antenna about its azimuth axis. Electrical signals for the antenna and the drive motors are multiplexed and passed through a single coaxial cable in a rotary joint along the axis of azimuth rotation.

Abstract: Since the mobile satellite communication antenna according to the present invention has the antenna board provided on the top surface of the rotary member in the state in which a part of the antenna board protrudes outward in the radial direction from the outer periphery of the rotary member, the antenna board doubles as a member for preventing the belt from coming off and reduces the number of parts, which can provide an antenna which is inexpensive and compact and is easily assembled.

Abstract: A mechanical scanning and digital beamforming antenna (20, FIG. 2) uses a receive and transmit digital beamforming network (FIG. 3, 410, 320) to provide communications beam scanning in a first plane. In a second plane, a reflective surface (FIG. 2, 240) is used to focus and scan the communications beam. Through proper orientation of the reflective surface (240), a communications satellite (FIG. 1, 10) can be tracked by way of electronic scanning by way of the transmit or receive digital beamforming network (FIG. 3, 320, 410). Thus, the complexity of the digital beamforming network is reduced as is the wear on the mechanical components of the antenna. The mechanical scanning and digital beamforming antenna (20, FIG. 20) makes use of a second digital beamforming network (FIG. 3, 415, 325) and reflective surface (FIG. 3, 250) to ensure that two communications satellites can be simultaneously tracked.

Abstract: An electronically scanned antenna that is manufactured using semiconductor material and device fabrication technology. The antenna has a semiconductor substrate having a plurality of stubs projecting from one surface. The semiconductor substrate may be silicon, gallium arsenide, or indium phosphide, for example. A first conductive layer formed on the surfaces of the semiconductor substrate and along sides of the stubs so that the stubs are open at their terminus. The conductive layers form a parallel plate waveguide region. A diode array having a plurality of diode elements is formed in the semiconductor substrate that are disposed transversely across the semiconductor substrate and longitudinally down the semiconductor substrate between selected ones of the plurality of stubs. The diode array may comprise an array of Schottky or varactor diodes, for example.

Abstract: An antenna assembly for a communications network is disclosed, the assembly comprising an antenna which is operable in different modes of operation; wherein, in a first mode, the antenna is operable as a scanning antenna to scan and thereby determine a communications link with a selected one of a plurality of base stations and in a second mode is operable as a communications antenna to communicate with the selected one of the plurality of base stations. Control means are provided which are operable to receive data from the antenna when operating in a scanning mode, to determine which base station should be used for future data communication and can move the orientation of the antenna such that it is operable to communicate with selected one of the base stations. A method of operation is also disclosed.

Abstract: A Cassegrain antenna system includes a flat dielectric plate radome having a thickness of one-half wavelength at a frequency of operation. The plate has an electrically conductive grid disposed on an inside surface thereof to permit perpendicularly polarized energy rays to pass there-through. A parabolic twist reflector is spaced from the radome, and includes a dielectric substrate having a thickness equivalent to one-quarter wavelength at a frequency of operation and having formed on an interior surface thereof an array of conductive strips oriented by 45 degrees relative to the incident ray polarization. A conductive ground layer is formed on an exterior surface of the substrate, wherein radiation reflected by the ground layer and passing through the dielectric substrate is shifted by 180 degrees in phase and is rotated in polarization when combined with energy reflected from the conductive strip array by 90 degrees relative to radiation incident on the twist reflector.

Abstract: A user terminal (110) includes a rotating electronically steerable antenna system (210) which combines coarse mechanical beam steering with fine electronic beam steering to provide full hemispherical coverage and enable hand-offs in a satellite communication system. The antenna system (210) comprises at least one antenna unit (and preferably two antenna units) including a mechanically rotatable base (330), an antenna holder (320) coupled to the mechanically rotatable base, and two electronically steerable antenna subunit (310) mounted on the antenna holder. Antenna system (210) also includes an antenna unit controller (260) adapted to control rotation of the mechanically rotatable base (330).