Abstract: A two-dimensionally steered antenna system (40) includes a planar lensing system (64, 94) operable to focus signals received from a plurality of ground-based cells (20). A first steering system (66) is operable to steer a beam (32) for each ground-based cell (20) in a first direction by weighing signals associated with the ground-based cell (20) based on a position of the antenna system (40) relative to the ground-based cell (20) in the first direction. A second steering system (96) is operable to steer the beam (32) for each ground-based cell (20) in a second direction by weighing signals associated with the ground-based cell (20) based on a position of the antenna system (40) relative to the ground-based cell (20) in the second direction.

Abstract: A sectored antenna system has one or more dielectric lenses, each having a surface and two or more antenna feed devices tilted non-parallel to the lens surface and preferably angled in a V pattern. At least one of the feed devices radiate signals into said lens that emerge as separate directional beams, or the lenses receive incoming signals from different directions and focus them onto different antenna feed devices. The feed devices of the sectored antenna system have a dielectric constant of between about 5 and 15 and preferable about 10 and further has a mounting collar to mount the antenna feed devices about the lens to adjust for elevation, azimuth, radial and rotational orientation.

Abstract: The low profile antenna assembly comprises a generally rectangular frame member housing a planar antenna. A radar absorbing material is attached to the front side of the housing with a radome covering the front side of the planar antenna and attached to the frame member. The planar antenna is a microstrip array fed by a beam forming network that uses either delay lines or phase shifters to electronically steer the antenna pattern horizontally and vertically. The antenna assembly is weatherproofed, painted and flush mounted against a building surface for camouflaging the antenna assembly from observers at a distance.

Abstract: An electromagnetic lens comprises two conductive sides between which there is arranged a cavity provided in its lateral portion with electromagnetic input/output coupling transitions to authorize a set of propagation laws between pairs of such inputs/outputs. Moreover, it comprises, substantially centered in the cavity, a substrate comprising a printed conductive patch of predetermined dimensions, so that the two conductive sides and the patch thus create a suspended three-plate strip line structure. The content of the cavity and the respective geometries of the cavity and of the conductive patch are chosen to comply with the propagation laws.

Abstract: The invention relates to an antenna system which is capable of producing multiple, high-gain, independently steerable antenna beams from a single antenna aperture. The system accomplishes this, in part, by utilizing a separate phased array antenna as the feed element of a spherical lens for each desired beam. In this fashion, the beam(s) produced by the antenna system can each be electronically steered (independently of the other beams, if any) and physical movement of the feed element(s) is not required. The invention may also use multiple spherical lenses, wherein each lens includes at least one phased array feed.

Abstract: An array of hemispherical dielectric lenses antenna on a ground plane for focusing radiation from an array of point sources, each point source being located adjacent to its respective hemispherical lens. Dual polarization point sources provide dual orthogonally polarized radiation patterns, including right and left hand circularly polarized radiation patterns. The entire antenna and ground plane may be rotated and the array of point sources may be moved relative to the hemispherical lenses so as to scan the antenna beam over a hemisphere.

Abstract: A semi-cylindrical dielectric lens antenna on a ground plane for focusing radiation from a line source adjacent to the semi-cylinder. Grooves in the surface of the ground plane modify the polarization of the electromagnetic radiation reflected by the ground plane thus allowing conversion of radiation from linear to circular polarization and vice versa. Selectable line sources may be used to provide both right and left hand circularly polarized radiation. The entire antenna and ground plane may be rotated and the line source may be moved relative to the dielectric lens so as to scan the antenna beam over a hemisphere.

Abstract: A low radar cross section lens antenna having high gain is disclosed. A spherical lens having a dielectric radial gradient focuses planar RF energy coupled thereto onto a focal point on the surface of a lens located diametrically opposite from the first intersection of the plane wave and the lens. The lens partially encloses a wedge shaped RF absorbing portion having the edge of the wedge passing through the center of the lens. The lens is partially surrounded by a second RF absorbing portion having a bowl-like shape. An antenna feed having its aperture located adjacent the surface of the lens is mounted to rotate about an axis lying substantially along the edge of said wedge shaped absorbing portion. Elevation rotation means is provided to rotate the feed antenna within a slot contained within the second RF absorbing portion.

Abstract: An improved spherical gradient lens and a method of fabricating same. A uniform sphere of a material such as high density irradiated polystyrene or a methylpentene copolymer in the polyolefin family having a uniform relative dielectric constant is provided. A plurality of radially extending holes are formed therein, for example by drilling, the holes having a predetermined cross sectional geometry along axes extending radially from the center of the sphere. The geometry of holes is selected to control the resultant local density of material, and thus the relative dielectric constant as a function of distance from the center of the sphere. Hole diameters are chosen so as to be small compared to the shortest wavelength of interest with which the lens will be used.

Abstract: An antenna system for receiving radiowaves includes a Lundeburg-type lens which reflects radiowaves to a focal point of the lens. A helical primary feed is located in the proximity of the focal point. Electronic circuitry for processing the radiowaves in a desired manner and the primary feed are supported in a hollow support structure in the proximity of the focal point.

Abstract: An antenna system capable of receiving electromagnetic radiation having either right or left helical polarization, and either vertical or horizontal linear polarization includes an energy concentrator which concentrates energy at a focal point. A helical antenna is arranged in the proximity of the focal point. A first switch switches the helical antenna to a backfire mode of operation and a second switch switches the helical antenna to an end fire mode of operation. A control mechanism controls the switches to select the nature of the polarization.

Abstract: An electromagnetic field sensor for use in a target seeking missile which asures the amplitude, phase, frequency and polarization of an incoming electromagnetic field as well as the angle of arrival of the incident electromagnetic field. A Luneberg lens is mounted in the radome of the missile. The Luneberg lens focuses an electromagnetic wave reflected from a target which then passes through the radome and enters the Luneberg lens on one side of the lens onto a point on the opposite side of the lens. A photonic sensor which may be a single electro-optic modulator or a pair of electro-optic modulators is positioned on the Luneberg lens at the point upon which the incident electromagnetic wave is focused. When a pair of electro-optic modulators are used as the sensor the sensing axis of one of the electro-optic modulators is generally perpendicular to the sensing axis of the other electro-optic modulator.

Abstract: An electromagnetic field sensor apparatus which measures the field strength and phase of an incident electromagnetic field as well as the angle of arrival of an incident electromagnetic field. The electromagnetic field sensor apparatus comprises a Luneberg lens which focuses an incoming planar electromagnetic wave entering on one side of the Luneberg lens onto a point on the opposite side of the lens. A photonic sensor is positioned on the Luneberg lens at the point upon which the electromagnetic wave is focused. A light source is located along an optical path which passes through the photonic sensor for transmitting polarized light through the sensor. The photonic sensor modulates the polarized light passing therethrough when the photonic sensor detects the incident electromagnetic wave. A photodetector located along the optical path detects the modulated light as it exists from the photonic sensor.

Abstract: A wideband shaped beam antenna having steep beam edge slopes in one plane is disclosed. An optical multiple beam antenna such as a geodesic lens antenna, a Luneberg lens or a circular folded pillbox, is coupled at selected points to a feed system having a power divider and phasing control. Coupling of the feed system to the optical multiple beam antenna is effected with a power transition having a wide frequency bandwidth and a capability of conducting high power levels. To shape the beam further, selected beams may be amplitude weighted. An aperture control device such as an E-plane sectoral horn, is attached when required, to narrow the beamwidth in the E-plane. By overlapping multiple beams of the optical multiple beam antenna in accordance with the invention, a sector beam having a constant position and constant steep edge slopes over an octave frequency bandwidth is obtained.

Abstract: Receiver apparatus for receiving electromagnetic target radiation polarized in a first direction includes a dielectric lens having forward and rearward surfaces. The received target radiation is refracted at the forward surface and reflected by the rearward surface. An antenna array is disposed adjacent one of the forward and rearward surfaces for receiving (a) the target radiation reflected from the rearward surface, and (b) a local oscillator beam haivng a polarization direction which is orthogonal to the polarization direction of the target radiation received at the antenna array.

Abstract: An optical spherical Luneburg lens is described which is also useful for millimeter wave and microwave operation, which can provide a multitude of simultaneously acting receiving beams over a hemispherical or spherical field of view. When used in conjunction with surface mounted optical/radio frequency pickup elements, the lens can be employed in a passive target detection system of unique field of coverage and sensitivity. The lens comprises a center sphere of refractive index of approximately .sqroot.2, around which are arranged in concentric shells of aerogel material. The aerogel material of the respective shells is fabricated to obtain a particular index of refraction approximately equal to (2-(r/r.sub.0).sup.2).sup.1/2, where r is the radius of the shell and r.sub.0 is the radius of the lens assembly. The lens can be employed in a system providing dual mode simultaneous optical and radio frequency operation with a single aperture.

Abstract: The invention disclosed relates to gun-launched target projectiles wherein a radar-augmentor is included to increase the radar cross-section of the projectile to simulate on radar, an actual airborne threat such as aircraft and missiles. The radar augmentor comprises a base member, a uniform dielectric lens attached to said base member and a resilient support means between said base member and said lens. The dielectric lens is configured to provide a frontal radar return echo which simulates the actual airborne threat on radar.

Abstract: A passive radar target comprises a sond lens (50) of substantially uniform dielectric constant, having a reflecting surface (51) integrally formed therewith, the lens being constructed of particulate material having a dielectric constant selected such that radar waves striking the surface of the surface of the lens are focussed on the reflecting surface. In one form the particulate material comprise silica flour (91, 101) contained within a thin radar transparent polycarbonate shell. The shell is formed of two similar halves (102, 103) with a pressed aluminum reflective lining (92, 106) in one half. By making the lens axially symmetrical such that the forward and rearward surfaces have a radius of curvature that decreases with distance from the axis of symmetry (102, 103) the lens-reflector can be made to operate over a wide solid angle.

Abstract: An improved Lens/Polarizer/Radome system to modify the antenna pattern of an existing array antenna is shown to consist of a unitary assembly made up of a dielectric lens of appropriate shape, polarization determining means and absorbing means, such assembly being disposed to cover the aperture of the existing array antenna.

Abstract: Multibeam lens antennas are often circular, and utilize propagation in disk-shaped parallel-surface regions. There is phase correction through terms in .theta..sup.2, where .theta. is the angle of an aperture point measured from the boresight direction. In the new designs herein, the lens comprises two portions, each being two closely spaced plates with a dielectric medium between them. One portion is formed as a surface of revolution (cylindrical or conical) with two circular ends, one end being an aperture with element feedpoints coupled to array elements. The other portion is a cap joined to the other end of the first portion. The cap may be a disk or a segment of a sphere. The dimensions and indices of refraction are selected to provide focus points for feed ports, with each focus being for a specific beam direction. The parameters may be selected so that the focus points are within the cap, at the periphery of the cap, or at the aperture. Some of the new designs have phase correction through .theta..sup.

Abstract: A multiple-feed Luneberg lens scanning antenna system. A Luneberg lens disposed for rotation. A first antenna feed is connected to and defines a first feed point on the surface of the lens. A plurality of second antenna feeds are respectively connected to and define a plurality of second feed points outside and closely adjacent the periphery of the lens. Supporting structure separately supports each of the second feeds at positions independent of the rotation of the lens. A drive system is coupled to the supporting structure for separately positioning each of the second feeds. The drive system also is coupled to the lens for rotating the lens to cause the first feed point to scan over a wide angle.

Abstract: A lens antenna of Luneberg type comprising a disc-shaped dielectric element having a radially varying diffraction index and bounded on both major sides by conductive metal plates. The antenna is preferably adapted for transmission of a wave which is polarized in an angle of 45.degree. relative to the plane of the lens element and is characterized in that the distance between the conductive plates and the lens element is filled with air or a dielectric having a corresponding dielectric constant.

Abstract: An antenna, preferably operating in the microwave range, comprising a Luneberg lens with a disc having a radially varying refraction index and provided with feeders distributed around the circumference. Each feeder has the shape of a thin wire the projection of which, as seen radially relative to the center of the round disc, forms a straight line inclined 45.degree. against the plane of the disc. All feeders are inclined in the same direction in their respective radial planes, whereby the feeders opposite a respective feeder will be oriented substantially perpendicular to the feeder permitting passage of radiation to and from the feeder. All of the feeders can be active simultaneously.

Abstract: A communications system is described which utilizes an antenna having means for selectively controlling the amount of incident electromagnetic energy directionally reflected therefrom. The antenna is comprised of a spherically configured array of conductors which focus incident energy on a reflector whose electrical conductivity characteristics and thus reflectivity characteristics can be controllably varied. The reflector can comprise a gas tube whose conductivity and thus reflectivity characteristics are a function of the number of ionized gas molecules therein. Modulation of the reflector reflectivity characteristics permits identification information, for example, to be impressed on the energy reflected therefrom.

Abstract: An antenna, preferably operable in the microwave range, comprising a disc-shaped lens having a radially varying refraction index, and having feeders distributed around the circumference. Each feeder is in the shape of a thin wire having a projection which, as seen radially relative to the center of the disc, forms a straight line inclined 45.degree. relative to the plane sides of the disc. All feeders are inclined in the same direction relative to the center of the disc and thus all diametrically-opposed feeders are oriented substantially perpendicular to each other. Because of this orientation, radiation focussed by the lens passes to and from any active feeder without being substantially disturbed by other feeders, and a plurality of feeders can be active simultaneously.

Abstract: A lens antenna of Luneberg type comprising a disc shaped dielectric element having radially varying diffration index or dielectric constant and surrounded on both plane sides by conductive metal planes. The antenna is preferably adapted for transmission of a wave which is polarized in an angle of 45.degree. relative to the plane of the lens element and is characterized in that the distance between the conductive planes to an essential extent is formed by air or a dielectric having a corresponding dielectric constant.

Abstract: A three-dimensional bootlace lens with minimum possible focusing aberrati, minimum possible focusing size and minimum possible dielectric loading. The feed and lens surfaces are in the shape of a spherical cap and covered by contiguous arrays of radiators. The region between the inner surfaces of the lens is filled with a nonuniform dielectric material with an index of refraction which constantly changes from the center line outwardly. Lens ports are connected to a radiating antenna array by means of coaxial transmission lines all of which have the same length. The axial feed point has a focusing performance which is perfect. For all other points the lens is free of all first-order aberrations except coma. The outputs of the lens can be used to feed a planar radiating antenna array so as to produce a multiple directive beam in one angular dimension or to feed a circular array so as to make it amenable to scanning or multibeam feed systems that are used with linear arrays.

Abstract: A lightweight mixed dielectric and a manufacturing method thereof is described, which is prepared by mixing metal-coated expanded particles of plastic, glass or silica, thin-wall metal pipes or metal coated thin-wall plastic pipes and uncoated expanded particles of plastic, glass or silica and then forming the resulting mixture into a desired shape by thermal expansion or by the use of binder with the provision that these uncoated expanded particles are only made of plastic when the forming step is carried out by thermal expansion.

Abstract: An antenna system having a multiple of antenna feeds to drive a microwave ns, composed primarily of a Luneberg lens and a metallic ground plane upon which are mounted three antenna feeds and a shorted stub (or four bent-stub coaxial feeds). The antenna system uses a common aperture to provide antenna performance for the three separate feeds, conserving space that would normally be required for three separate high gain antennas.

Abstract: A feed system for scanning focal plane antenna systems with which a variable focal spot illumination may be achieved within the focal region of a primary antenna over a limited scanning sector is disclosed. An array of collector elements positioned to receive radiation from a scannable feed antenna is coupled to an array of radiator elements positioned in the focal region of the primary antenna, the positioning of the radiator and collector elements are such that the focal spot illumination is caused to vary with the scan angle of the antenna.

Abstract: A luneberg type passive reflector for circularly polarized waves consists of a woven cloth made partially of conductive wires located within the dielectric sphere the surface of which is covered with a set of parallel wires perpendicular with the conductive wires in said cloth. The conductive wires of the cloth are less than five hundredths of wavelength in diameter and their spacing is between 1/4 and 1/20 of a wavelength. The wires interwoven with said metal wires to form the cloth are preferably made of flax.

Abstract: There is disclosed an electronic steering circuit suitable to be utilized in scanning antenna array systems for automatically steering receive and transmit signals between particular antenna elements and a plurality of transceivers. In the preferred form, the electronic steering circuit is coupled between each one of a plurality of antenna elements and a lens, such as a Luneberg lens. Each steering circuit is adapted to be connected to a particular transceiver. Transmitted signals from the transceiver are routed through the steering circuit to the lens and cumulated receive signals from the lens are routed through the steering circuit to the transceiver.

Abstract: 1. A reflectance modulator exhibiting an omni-azimuttal reflectance pattern comprising a microwave lens for focusing electromagnetic energy, a plurality of reflector means positioned on a focal surface of said lens and including a gaseous plasma, means for sequentially controlling the ionization level of said plasma to modulate the reflectance of said energy.

Abstract: A Luneberg lens with a polarization-sensitive spherical "leaky" reflector cap having conductive strips aligned at a 45.degree. angle to the linear polarization of the incident wave. The ratio of strip width to strip spacing is preferably chosen to reflect back a cross-polarized component about -10 db below the reflected self-polarized component. The strip width is small as compared to the focal spot diameter of the lens for any given incident wave direction and also small as compared to the wavelength of the incident wave. The lens and reflector can be used in small drone aircraft to simulate the radar cross section of a larger body such as an aircraft whose radar cross section causes reflected polarization components not present in the incident field. The full specification must be consulted for an understanding of the invention.