Abstract: A satellite-based cellular telecommunications system employing a constellation of telecommunications satellites in medium earth orbit to provide multibeam radio frequency (rf) communications links for worldwide cellular telephone service with a minimum number of satellites. The telecommunications satellites are placed in a plurality of inclined orbits about the earth at an altitude of between approximately 5600 and 10,000 nautical miles. The characteristics of the orbits, such as the number of orbits, the inclination of each orbit, the number of satellites in each orbit and the altitude of the satellites, are tailored to maximize the coverage area of the satellites and their related line-of-sight elevation angles, while minimizing propagation time delays, the number of beam-to-beam and satellite-to-satellites handovers, and the total number of satellites.

Abstract: An antenna having antenna modules for an extremely wideband active monopulse phased array system, the modules including a housing provided with four radiators of the rectangular open-ended waveguide type and with an electric circuit. With the antenna modules being suitably stacked, the radiators constitute a substantially continuous antenna surface, the radiators being positioned at the points of intersection of a system of equilateral triangles which make up the antenna surface. After preamplification, phase shift and down-conversion to an intermediate frequency, received signals from a large number of antenna modules are combined to yield a sum beam, an azimuth difference beam and an elevation difference beam.

Abstract: 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.

Abstract: The present invention relates to an array antenna for receiving a signal in a microwave band. The array antenna includes a plurality radiating element arranged in subarrays, each subarray having a first feeder connected to the radiating elements and a low noise amplifier (LNA) connected to receive the output of the first feeder, a frequency converter, and a second feeder for combining the outputs of the sub arrays from the LNAs. According to this structure, in the formula representing the noise temperature observed at the radiating elements, the gain the LNA appears in the denominator in the term representing the loss of the second feeder which combines the outputs of the sub arrays. Therefore, if the gain of the LNA is sufficiently large, it is possible to disregard the influence of the loss of the first and second feeders for combining the outputs of the sub arrays on the noise temperature.

Abstract: A linear conformal array antenna consisting of double-ridged waveguide elements which are all tapered in the E-plane or the H-plane. The array of waveguide elements is fed by a Gent lens whose amplitude and phase characteristics can be adjusted to cause the waveguide element array to produce a desired radiation pattern. The linear array antenna, which has been tapered in the E-plane, can be operated to scan an electromagnetic endfire beam in one predetermined direction with a maximum scan loss of 3 dB. The array of waveguide elements can be substantially conformal with the fuselage of an airborne craft carrying the linear array antenna, thereby reducing aerodynamic drag and radar cross section. The linear array antenna has a bandwidth that is greater than an octave wide.

Abstract: An antenna scanned by frequency variation, comprising: exciter means for producing a plane electromagnetic wave at a given frequency which is variable about a center frequency; and radiating means receiving the plane wave produced by the exciter means and subjecting the plane wave to a plurality of successive reflections, the radiating means including means for allowing a fraction of the plane wave to leak to the outside after each successive reflection in order to enable it to radiate to the outside; the phase shift of the wave between two reflections varying as a function of the frequency of the wave and the set of radiated waves produced in this manner thus having a determined relative phase difference, which is variable as a function of the frequency of the wave generated by the exciter means and which defines transmission having a main lobe whose direction is itself variable as a function of the said frequency.

Abstract: A microwave array antenna comprises a plurality of like unit sources whose width increases progressively from the center of the array towards its ends and which are disposed relative to each other in such a way that substantially no illumination gaps are created in the array.

Abstract: A phased array antenna includes an array of phase shifters, each shifter being operable for shifting the phase of RF energy passing therethrough. Each shifter includes a quantity of ferroelectric material disposed throughout a region. RF energy propagating from a source passes through the material. A thin conductive electrode is disposed in the center of the material, the electrode having a bias voltage imposed thereon. Such voltage creates an electric field across the material, which for a uniaxial ferroelectric orients the optic axis of the material in a direction which is both normal to the direction of propagation of the RF energy and parallel to the polarization direction of the RF energy. The electric field changes the wave propagation constant (i.e., for a uniaxial ferroelectric, the extraordinary wave refractive index, n.sub.e), producing a varying path length of the RF energy in the material, resulting in a controllable alteration of the phase of the RF energy.

Abstract: The power or frequency characteristics of a layered frequency selective surface assembly (1) having a dielectric substrate layer (2) and, superimposed therewith at a spacing (X) therefrom, at least one layer (3) of electrically conductive elements (4) disposed in an array, is modulated by moving at least one layer (2, 3) relative to the or each other layer (2, 3). The layers (2, 3) maybe substantially planar or substantially non-planar and may be disposed substantially parallel to one another. Relative movement between the layers (2, 3) may retain the substantially parallel orientation or may not retain the substantially parallel orientation. The relative movement may have the effect of changing the spacing between the layers (2, 3) for example to tilt, skew or rotate one layer relative to the or each other layer.

Abstract: Disclosed is an apparatus and method for shaping a beam of radiation from a circularly polarized beam shaping antenna to create a predetermined radiation pattern. A circularly polarized feed horn generates the beam of radiation to be shaped. Circularly polarized radiator elements attached to a ground plane are positioned to receive the beam of radiation. Each radiator element is physically rotated about an axis relative to the ground plane to alter its phase. The radiator elements are then operable to individually radiate a beam of radiation to form a combined radiation beam creating the predetermined radiation pattern.

Abstract: An antenna suited for a communications satellite includes two separately located, mutually orthogonally polarized feed antennas such as vertically and horizontally polarized linear horns. The horns feed an active reflector antenna array. The array includes a plurality of mutually orthogonally polarized antenna elements such as crossed dipoles or square patch antenna with cross feeds for two independent orthogonal polarizations. The feeds of the antenna elements are coupled to amplifier modules. Each module includes a circulator for each polarization, coupled to a processor including a low noise amplifier, controlled phase shifter, variable gain amplifier and power amplifier. The output of the power amplifier feeds the antenna element through the circulator. The large number of radiating elements allows high power using power amplifier with relatively modest capabilities.

Abstract: An amplitude monopulse direction finding system is disclosed. The system is built around a circular array with a circular lens in which the antenna elements and array ports are larger than in conventional systems. The oversized antenna elements and array ports provide a wide range of operating frequencies for the direction finding system. Additionally, the direction finding system contains an omni-directional probe at the center of the lens to detect the presence of signals. In an alternative embodiment, each array port is split into two halves which can be combined in different ways to produce different beam patterns, allowing the beam pattern providing the best signal to noise ratio to be selected. Also, built-in-test circuitry is described.

Abstract: 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.

Abstract: For setting up LOS radio links between mobile calling transmitting/receiving stations and other mobile or stationary remote transmitting/receiving stations in a predetermined operating area, especially in the frequency range above 1 GHz, every mobile station is provided with an electronic memory with an associated processor. The memory stores the respective geographical and topographical data of the operating area. Prior to the setting-up of a radio link, the transmission loss between the stations is calculated in accordance with known model calculations on the basis of the geographical and topographical data stored in the memory by inputting into the processor the current location data of the calling station and the remote station.

Abstract: A microstrip electronic scan antenna array is provided comprising a hollow elongated octagonal-shaped housing formed by four quadrantially-disposed microstrip patch antenna arrays and four filler panels extending between the patch arrays. Three, independently-switchable microstrip Y-junction circulators are tandem interconnected in a double-ended wye configuration on a common dielectric substrate forming an octagonal end cover for the housing. Each of the three circulators acts as a single pole-double throw switch and the sequence of energization of the four microstrip patch antenna arrays is determined by controlling the sequence and direction of circulator coupling action of the three circulators.

Abstract: An electromagnetic field sensor apparatus which measures the amplitude, pe, frequency and polarization of an incoming electromagnetic field as well as the angle of arrival of an incident electromagnetic field. A Luneberg lens focuses an incoming electromagnetic wave entering on one side of the Luneberg lens onto a point on the opposite side of the lens. A pair of photonic sensor which may be electro-optic modulators or Pockel cells are positioned on the Luneberg lens at the point upon which the incident electromagnetic wave is focused. The sensing axis of one of the electro-optic modulators is perpendicular to the sensing axis of the other electro-optic modulator. Polarized light is provided to each photonic sensor along an optical path which passes through the sensor. Each photonic sensor modulates the polarized light passing therethrough when the photonic sensor detects the incident electromagnetic wave.

Abstract: A constant gain sector beam array is obtained by applying equal amplitude, equal phase excitations to a sector array characterized by a curved array geometry. In a simple form, the curve is the arc of a portion of a circle. The radiation pattern can be further enhanced by using a more complex curvature geometry, and by minor adjustments to the amplitudes in the slots. Other forms of shaped beams, such as a cosecant squared antenna pattern, may be obtained by appropriately shaping the curvature geometry.

Abstract: A phase shifter for use in a phased array antenna includes a waveguide flange of metallic material has a narrow slot formed therein, the slot having ferroelectric material disposed uniformly therein. The slot is of reduced height relative to normal waveguide dimension, such height reduction minimizing the voltage applied across the material RF energy radiating from a source is directed to pass through the ferroelectric material. A single, thin conductive plate is disposed in the center of the slot, the plate having an electrical DC voltage imposed thereon. Such voltage creates an electric field across the material, which for a uniaxial ferroelectric orients the optic axis in a direction which is both normal to the direction of propagation of the radiation and parallel to the polarization direction of the radiation. The electric field changes the wave propagation constant (i.e., for a uniaxial ferroelectric, the extraordinary wave refractive index, n.sub.

Abstract: A microwave polarizing lens structure having two concentric hemispherical arrays of metallic linear scattering elements (dipoles) supported by thin walled dielectric shells. It has the property of controlling the sense of polarization, the ellipticity ratio and shape of the radiation pattern of the antenna contained within it.

Abstract: The present invention provides phased arrays using monolithic technology of diffusions over whole wafers for working in millimetric wave frequency bands. The reflector array includes a plurality of metallizations connected together by diodes whose capacity can be varied. Thus direct control of reactive impedances is obtained. With the metallized strips placed at a distance substantially equal to .lambda./4 from a ground plane, it is possible to control locally the phase of the reflected signal.

Abstract: Disclosed is a source of microwave radiation, namely a source enabling the absorption of multiple reflections for the illuminating of a lens in order to form an electronic sweeping antenna. The source includes a layered arrangement of elementary illuminators in a direction substantially parallel to the electrical field of the microwave energy transmitted. In one embodiment, each elementary illuminator has the following successively, in the direction of propagation of the energy: a plane forming a short circuit; a plane forming an incidence filter, parallel to the above plane, located at a distance from the above plane of the order of half of a wavelength, including two tracks parallel to each other and perpendicular to the electrical field between which resistive elements are connected; and, a plane bearing a rdiating element of the snake line type, extending in a direction substantially normal to the electrical field.

Abstract: An antenna including a lens that has an array of radiating elements located on a focal arc, each radiating element corresponding to a different transmission beam direction; and a beam launcher having a plurality of phased arrays and a plurality of internal probes, each of the plurality of internal probes being electrically coupled to a corresponding one of the radiating elements, the phased arrays for space feeding a selected one or more of the radiating elements with signals so as to generate corresponding transmission beams from the lens.

Abstract: An arrangement for measuring, at a plurality of points, the microwave field diffracted by an object. A microwave radiation source illuminates an object. Electric doublet antennae loaded by diodes are disposed in line along the path of the radiation diffracted by the object. A guide structure, with coupling antennae, is disposed along the line of doublet antennae and collects the diffracted radiation. Electronic circuits control the whole so as to measure the diffracted field at the position of each doublet antenna.

Abstract: An array antenna system producing beams with widths constant with scan angle. The antenna array is fed by a microwave lens. The beam ports of the lens are disposed along an arc displaced from the focal arc of the lens. The distance between the arc and the focal arm decreases from a maximum amount at the center of the lens to a minimum amount where the arc intersects the focal arc.

Abstract: An antenna system provided with an adjustable reflection coefficient includes at least one radiation source (1), a reflective surface (12) positioned in the path of the radiation generated by the active radiation source (1) and 9 light-generating means (13, 14). The reflective surface (12) is provided with semiconductor surfaces (2.i.j) with a spacer-therebetween and the light of the light-generating means (13, 14) is used to illuminate the semiconductor surfaces (2.i.j) such that, after reflection of the radiation generated by the active radiation source at the reflecting semiconductor surfaces, a radiation beam is obtained in which the beam width and beam orientation can be varied by adjusting the light intensity so as to adjust the phase of the reflection of the semiconductor surfaces.

Abstract: Disclosed is a device designed to selectively absorb the electromagnetic waves coming from multiple reflections in a microwave lens. In an antenna of the type including an energy source and a lens, where the lens is formed by a plurality of parallel channels separated by conductive planes, the device has a slot made in each of the conductive planes, arranged on the input face side of the lens, and also has localized or distributed resistors connecting the two edges of the slot. The geometry of the entire unit, and the values of the resistors are such that the waves coming from multiple reflections are absorbed by the resistors.

Abstract: A radar camouflage material for reducing the radar back-scatter cross section of a target object including a thin layer or foil of dielectric material provided with a plurality of individual antenna elements of the minimum-scatter antenna type, preferably ring antennas, which are loaded purely reactively.

Abstract: A radiating element comprises a groundplane, a dielectric layer and a conductive pattern comprising a folded dipole (20, 21), a feed line (18, 19) for the dipole and a plurality of closely spaced directors (22), all lying in a common plane parallel to the ground plane. An array of such elements with a suitable feed network provides a flat antenna with a squinted beam. The squint angle can be adjusted by adjusting the phase delay between columns of elements. The beam can be steered by selection of the appropriate squint angle and by rotationally adjusting the antenna in its own plane. The antenna is suitable as a less obtrusive alternative to a dish antenna.

Abstract: A progressive phase feed transmission line network for use with a Rotman-Turner lens is composed of a plurality of feed ports for receiving or transmitting energy from or to the lens, a pair of control ports, a plurality of different sets of transmission line segments with the segments in the same sets being of substantially equal lengths, and a plurality of power directors for splitting or combining energy depending upon whether the network is operating in a "receive" or "transmit" mode. Different phase delays are interposed in the network to provide a passive arrangement which can operate in the "receive" mode to determine directionality of energy received by an antenna array and fed through a Rotman-Turner lens to the transmission line network or can operate in the "transmit" mode in combination with adjusting of a phase shifter to directionally steer the energy launched into space by the antenna array after being fed from the network through the lens to the antenna array.

Abstract: The invention pertains to a modulation method at pick-up of the amplitude of the secondary lobes of the radiation pattern for a hyperfrequency antenna and the method application for sensing and eliminating the jamming effects of jammers.According to the invention, we place as a filter (4) close to the reflector (1) which reflects the transmission-pick-up beam of the antenna, the filter having at least one network of conductive wires loaded with variable controllable resistors, such as diodes. During transmission, we make the filter (4) transparent by having strong equal currents travel through the wires, while at pick-up we modulate the amplitude of the currents traveling through the wires in order to obtain the desired distortions of the pattern.The invention especially applies to the sensing and elimination of the jamming effects produced by jammers.

Abstract: A two-dimensionally scannable antenna system for transmission or receiving a microwave beam over a wide angular region, using multiple parallel plate lenses for focusing and to provide, in conjunction with a like number of phase shifters, scanning of the beam in one transverse direction, such as in azimuth. The multiple parallel plate lenses provide output signals for processing by a single diode grid lens, which provides for deflection of the beam about the other transverse axis, to scan the beam in elevation. The diode grid lens includes parallel conductive plates with a thickness tapered from a minimum value near the input and output of the diode grid lens, to a maximum value over most of the length of the diode grid lens. This increased thickness of the plates reduces the required number of switchable diodes in the diode grid lens. The device of the invention has fewer components, lower power consumption and corresponding lower cost than similar configurations available prior to the present invention.

Abstract: A distribution network for a modified space-fed phased array antenna consists of a planar array of radiating slots distributed along a coplanar wall in each of an ensemble of parallel waveguides. This waveguide ensemble is fed or excited by an orthogonal waveguide or waveguides, through a row of slots in a wall common to the excitation waveguides and the parallel waveguide ensemble, one slot per waveguide. A predetermined amplitude distribution is achieved in the plane parallel to the axis of the exciting waveguide by adjusting the coupling value of each exciting slot, and in the orthogonal plane by adjusting the displacement of the radiating slots from the center line of the waveguides, and by adjusting slot width, length, and geometry. Such an array of slots is used to feed the inside face of a quasi-space-fed antenna array having identical, individual electronics modules.

Abstract: The present invention concerns an electrically thin microwave phasing structure for electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band. The microwave phasing structure comprises a support matrix and a reflective means for reflecting microwaves within the frequency operating band. The reflective means is supported by the support matrix. An arrangement of electromagnetically-loading structures is supported by the support matrix at a distance from the reflective means which can be less than a fraction of the wavelength of the highest frequency in the operating frequency range. The electromagnetically-loading structures are dimensioned, oriented, and interspaced from each other and disposed at a distance from the reflective means, as to provide the emulation of the desired reflective surface of selected geometry.

Abstract: The microstrip constrained lens is a three-dimensional beamformer comprised of two printed circuit layers. The two circuit boards contain planar arrays of microstrip patches that face in opposite directions, to respectively collect and reradiate energy from a feed suspended behind the structure. It is a wide angle beamformer due to its use of two geometric degrees of freedom: the length of line joining front and back face lens elements varies with radius; and the back face elements are displaced radially instead of being placed directly behind their front face counterparts. An early version of this microwave lens used feed-through pins. In the most recent design the feed-through pins of the first model were replaced with a solderless slot coupler, or capacitive coupler. Without the need to solder the many hundreds of feed-throughs, the device is much easier to fabricate, and its performance is better because there is no degradation introduced by misalignment of the feed-through pins.

Abstract: The main object of the invention is an array of optically-controlled elements for the diffusion of electromagnetic energy. The invention pertains to an array capable of diffracting the electromagnetic energy which illuminates it, certain elements of the said array being capable of modulation. The device according to the invention comprises photodetectors which can be used for the optical modulation of the emitting/reflecting elements, whether diffusing or diffracting. The optical modulation provides for the individual control of each radiating element up to very high frequencies. Furthermore, the device according to the invention can be used to reduce the complexity of an array by doing away with the control wiring. The invention can be applied chiefly to the making of radar-testing devices, for example the simulation of bright points, the ultra-high-frequency tomography of the human body and the making of beacons.

Abstract: A lightweight antenna array which can quickly scan or switch radiation patterns, characterized by an array of slot-type radiators wherein the impedance of each radiating element can be varied, preferably by a computer controlled circuit containing particular groups of the radiators, wherein each grouping is defined by a unique set of impedance values for the radiators. The groups of radiators in the array can be slectively generated to scan and/or switch pattern footprints and/or change near-field radiation characteristics and/or alter antenna aperture size, density, distribution, spacing or frequency of operation. An adaptive technique, using an algorithm, can be employed to generate the radiator groupings.

Abstract: A directive communications antenna comprising upper and lower plates, each having a leading edge, and a parabolic reflecting cylinder disposed between and axially intersecting the plates so as to form a cavity having a focus line. The cavity is open adjacent the plate leading edges. Upper and lower lip plates respectively extend along the leading edges of the upper and lower plates with both lip plates projecting upwardly therefrom. A feed assembly comprised of a feed probe and a sub-reflector is positioned within the cavity.

Abstract: A multibeam antenna system in which an antenna aperture element is deliberately selected to produce a divergent beam at a desired angular beamwidth. The antenna aperture may, for example, take the form of a hyperboloid reflector, a diverging lens, or a defocused paraboloid reflector. For the divergent secondary beams produced in these configurations, the angular beamwidth may be conveniently controlled by varying the mangification of the aperture or the degree of defocusing, without significantly affecting the gain or efficiency of the system. The degree of beam overlap may be independently controlled by scaling the size of the aperture, without significantly affecting the beamwidth, the gain or the efficiency.

Abstract: A frequency independent constant beamwidth lens antenna concept is descri utilizing a point source to point focus nonspherical lens. The essential feature is that a twisted planar or hyperbolic paraboloidal phase or wave front is formed by the antenna which then in turn produces a frequency indepenent constant beamwidth beam in the far field of the antenna for radiation or reception of planar or nearly planar spherical waves. Moreover, the frequency independent constant beamwidth beam may be steered or scanned in azimuth without moving the lens antenna or a plurality of fixed beams in different directions may be formed simultaneously by the lens antenna.

Abstract: A radio frequency antenna system comprising a plurality of antenna elements arranged in an array, such array comprising a pair of subarrays of antenna elements coupled to a pair of electromagnetic lenses. Each lens includes a plurality of array ports, the plurality of array ports of the first lens being coupled to the antenna elements of a first one of the pair of subarrays, and the plurality of array ports of the second lens being coupled to the antenna elements of a second one of the pair of subarrays. The first lens further comprises a first set of beam ports, and the second lens further comprises a second set of beam ports, the first and second sets of beam ports being arranged to form corresponding first and second sets of interleaved beams of radio frequency energy.

Abstract: An optical limited scan antenna system is disclosed. The invention is a dual lens type array antenna system with a small array feed network. The system includes a bootlace-type microwave aperture lens with an array of radiating elements arranged along the linear aperture and an array of pickup elements arranged along the curved inner surface, an intermediate optical corrective lens, a feed array for illuminating the corrective lens with a source distribution, and with a power divider and phase shifters arranged to drive the feed array. The corrective lens is circularly symmetric (spherically symmetric in the three-dimensional case), and its radially varying dielectric constant is such that a point source on its surface is focused to an image point on the inner surface. The pickup elements on the curved surface of the aperture lens are coupled to corresponding radiating elements on the linear aperture.

Abstract: A large scan antenna, particularly for embarked use on board a satellite and for operation in the ultrahigh frequency range, of the type formed of a feed and a main fixed secondary reflector, the antenna being readily foldable into a launching configuration with a minimum of component elements, and comprising at least one guide G each formed of a first and a second parabolic secondary reflectors (12, 13) aligned optically along the axis of the wave guide G between the feed (10) and the main reflector (15), said wave guide G being on the one hand variable in length by moving at least one (13) of said secondary reflectors with respect to the other (12) along the axis (14) of the wave guide G, and on the other hand, rotatable about the axis (11) of the feed (10).

Abstract: A radar system with auxiliary scanning provision for providing more dwell time on target, the system having a main frequency scan antenna with electronic or mechanical arrangements for auxiliary scanning. In the electronic embodiment, a space fed phased-array auxiliary antenna is provided, the radiating elements being interconnected with diode phase shifters, which are electronically actuated and synchronized to the antenna rotation. In the mechanical embodiment, a multi-sided prism arrangement in front of the antenna rotates in synchronism in a counter direction to the antenna, with auxiliary scanning data electronically manipulated for processing.

Abstract: An electronically steerable antenna which refracts an electromagnetic wave travelling through an electrooptic deflector, steers an electromagnetic wave to a desired angle. The electrooptic deflector includes first and second sections of electrooptical material. A voltage changes the indices of refraction of the electrooptical material, thereby causing a change in the angle of refraction at the interface between the first and second sections. Input and output impedance matching sections are provided effecting maximum power transfer of the electromagnetic wave travelling through the antenna.

Abstract: In a multimode or multispectral electromagnetic detection system (11), a pair of rotatable scanning prisms (13' and 13"), each of said prisms comprising at least a pair of cooperative subprisms (13'a, 13'b, 13"a and 13"b), and the cooperative materials of the subprism being selected so as to ensure that electromagnetic radiation passing through the pair of rotatable prisms is equally deviated in a transverse direction.

Abstract: The surface area utilization efficiency of an array of antenna elements distributed over a prescribed geometrical surface is increased by configuring that surface as an ellipse of revolution. Preferably, the ellipsoid surface over which the antenna elements are distributed has a shape such that the major axis of the ellipse in rotation is twice the length of the minor axis. This results in an optimal, near constant illuminated surface area for any angle in the hemisphere. Because a more efficient use of the antenna surface area is provided, the number of antenna elements that is required to obtain the same array gain in all directions in the hemisphere can be reduced substantially when compared with spherical or tetrahedral configurations of conventional hemispherical coverage arrays.

Abstract: A multimode, multispectral antenna system (14) for detecting radiation from selected target regions in each of at least a pair of selected spectrum bandwidths through collimating lens (35), and rotatable, cooperative prisms (21) effective for collimating and scanning beams of radiation controllably with respect to said target regions.

Abstract: Doppler radar apparatus for use in a velocity measuring system for farm tractors and the like. The apparatus includes a dual mode conical horn having a flare angle substantially in excess of 12.5.degree., and a dielectric lens formed of a glass filled polymer. The doppler output signal provided by the RF transceiver associated with the dual mode horn is high pass filtered to remove low frequency signals therefrom. The horn is mounted in such a way that it is isolated from mechanical vibrations which would induce doppler signal frequencies in excess of the cutoff frequency of the high pass filter. Moreover, the horn assembly (which is aluminum) and a steel housing assembly are coupled together in such a way that thermal expansion and contraction will not loosen the friction fit between the two assemblies. The two assemblies are held together by a single, large diameter annular locking ring.

Abstract: Antennas chiefly intended for microwave and millimeter-wave use include geometric-shaped conductive patches on one broad surface of a planar semiconductor substrate. The other broad side of the substrate bears a conductive ground plane. Monolithic PIN diodes are formed by doping the substrate at various points between the conductive patch and the ground plane. Biasing arrangements affect the conduction of the PIN diodes thereby affecting or tuning the optimum operating frequency, the radiation pattern, and/or the impedance of the antenna. In a particularly advantageous configuration, the PIN diodes have lateral dimensions greater than or equal to one-tenth wavelength (.lambda./10) at the operating frequency. Distributed diodes have lower resistance and reactance than discrete or discrete monolithic diodes, thereby providing improved radiating characteristics, and have a relatively large power-handling capability which makes them useful for power transmission.

Abstract: 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.