Showing papers on "Reflector (antenna) published in 1981"

Phased array antenna employing linear scan for wide angle orbital arc coverage

Abstract: The present invention relates to phased array antenna arrangements which comprise a linear array of feed elements where the array has an aperture which is out at a bias angle along the minor axis of the array to produce a fixed linear phase taper along the minor axis by all elements Then by linearly scanning the array along the major axis of the aperture of the array, a beam is scanned along an arc which can be made to correspond to an orbital arc segment around a celestial body and within the field of view of the antenna arrangement when the bias angle is properly chosen The feed elements can comprise long feedhorns or horn antenna configurations which can be used in a separate array or disposed in an array on a conjugate plane of a main cylindrical reflector when used in multiple reflector phased array antenna arrangements

Rings as elements for frequency selective surfaces

Abstract: Arrays of simple rings on close packed square or triangular lattices are useful frequency selective surfaces for reflector antennas. Reflection bandwidths of about 26 per cent and transmission/reflection band ratios of 3:1 are readily attainable for angles of incidence of up to 45° at least. Experimental transmission coefficients are compared with the results of modal computations.

Preliminary design of large reflectors with flat facets

Abstract: A concept for approximating curved antenna surfaces using flat facets is discussed. A preliminary design technique for determining the size of the reflector surface facets necessary to meet antenna surface accuracy requirements is presented. A proposed large microwave radiometer satellite (MRS) is selected as an application, and the far-field electromagnetic response of a faceted reflector surface is compared with that from a spherical reflector surface.

Scanning capabilities of large parabolic cylinder reflector antennas with phased-array feeds

Abstract: Two methods of scanning large parabolic cylinder antennas are examined: one method moves a small array across the focal plane to form a scanning beam; the other method employs a larger stationary array which is capable of electronically scanning the beam. With conventional single-element feeds, the maximum possible scan angle decreases with increasing reflector size. With array feeds, however, the scan limits are shown to be independent of reflector size and antenna gain. Antennas with movable array feeds are found to have high performance (high gain and low sidelobes) even when scanned more than ten degrees off axis; antennas with stationary array feeds degrade rapidly beyond about one degree of scan because of aperture blockage. Off-axis designs which eliminate the aperture blockage are shown to extend the coverage of antennas with stationary feeds to about \pm 5 degrees.

Security system with infrared optical position detector

Abstract: A security device for determining the opening or closed condition of an access gate, such as a door or window hinged within an opening in a wall, has a detector unit mounted on the wall adjacent to the opening and linked to a remote control unit by a radio transmitter in the detection unit and a radio receiver in the control unit. The detection unit has an infrared generator and an infrared detector isolated from the generator, the detector and generator confronting a reflector mounted on the access gate when the access gate is closed. The reflector is translated from the field of the infrared generator when the access gate is open. The infrared generator is excited by a pulse generator to produce pulses of infrared radiation, and the scattered radiation from the reflector is detected by the infrared detector to produce electrical pulses coincident with the pulse generator. A coincidence circuit determines the presence of the detected pulse, and the absence of coincidence results in the transmission of a radio wave from the detector unit to the control unit to establish alarm conditions.

Strobe reflector assembly

Abstract: A strobe lighting unit--and a reflector assembly forming part thereof--include a concave reflector having a predetermined shape, typically including a parabolic cross-section. The reflector is formed in situ as part of an assembly process by pressing a thin precut planar blank of reflective material, preferably an aluminum alloy foil having selected mechanical properties, into a die cavity in the reflector housing with a conforming die plunger to bend the blank into the predetermined shape. During the bending process residual tension forces are induced intentionally into the blank and these forces urge the foil into contact with surfaces defining the die cavity to supportively maintain the reflector in the predetermined shape.

Fiber optic differential sensor

Abstract: An optical differential sensor utilizes at least two optical waveguides to receive light directly from another waveguide or reflected from a mirror to sense the position of the waveguide or reflector relative to the position of at least two waveguides. Relative positions may be influenced by ambient conditions or from mechanical motions, thus affecting an environmental or metrical sensor.

Solar cell having improved back surface reflector

Abstract: This invention is concerned with reducing the operating temperature and increasing the output of a solar cell. A solar cell (10) constructed in accordance with the invention carries electrodes (22) in a grid finger pattern on its back surface (12). These electrodes are sintered at the proper temperature to provide good ohmic contact. After sintering, a reflective material (24) is deposited on the back surface by vacuum evaporation. Thus, the application of the back surface reflector is separate from the back contact formation. Back surface reflectors formed in conjunction with separate grid finger configuration back contacts are more effective than those formed by full back metallization of the reflector material.

Tracking reflector assembly for a skylight

Abstract: A tracking reflector assembly for a skylight includes a ring-shaped base member rotatably supported above the skylight by a plurality of rollers which engage a channel formed within an annular wall of the ring. A reflector is pivotally coupled to the ring for reflecting light into the skylight to supplement light which strikes the skylight directly. A vertical drive motor operates in response to a pair of photosensors for raising and lowering the reflector to follow changes in the angular elevation of the sun. The ring-shaped base member includes a toothed lower surface engaged by a gear coupled to a horizontal drive motor for rotating the ring-shaped base member in response to a third photosensor for following east-to-west movement of the sun. Each of the aforementioned photosensors is normally shaded and actuates the associated drive motor only when being struck by direct sunlight. A vertical limit switch limits the amount by which the reflector may be pivotally raised to avoid reflecting midday summer sunlight into the skylight. Another switch is responsive to closure of the reflector over the base member for preventing the vertical drive motor from attempting to further pivot the reflector downwardly. A fourth photosensor senses darkness resulting from sunset or heavy overcast conditions for pivoting the reflector downwardly and returning the base member and reflector to an easterly direction. A limit switch senses the return of the base member to the full east position for terminating actuation of the horizontal drive motor. A user operated switch selectively enables the tracking reflector assembly to operate automatically or causes the reflector to be lowered and the base member to be returned to the full east position until the user again enables the automatic control circuitry.

Concentrating photovoltaic solar collector

Abstract: The disclosure illustrates a concentrating photovoltaic collector comprising an elongated deep reflector having a rim angle of close to 90° and an elongated series of photovoltaic cells positioned in a plant extending parallel to and spaced beyond the focal axis of the reflector. The cells are mounted in an extrusion that provides a passage for a cell coolant fluid and which has a pair of elongated opposed reflectors inclined toward one another at an angle of 70° with respect to the plane of the photovoltaic cells. The mirrors re-reflect rays to compensate for the shadows cast by the cells and to provide more uniform distribution of solar energy while at the same time permitting a more compact collector.

Expandable panel and truss system/antenna/solar panel

Abstract: Disclosed is an expandable panel and truss structure capable of being stowed in a storage container (canister) for transportation into space and deployed to form structures such as antennas, solar panels or similar space or terrestial structures. The antenna formed comprises the panels stored as hinged pairs (sets) folded in accordian-like fashion together with the expandable trusses and other devices necessary for antenna space operation, such as attitude control and antenna feed. The panel sets are deployed from the canister to form a toroidal ring, circular in cross-section when deployed, for supporting the antenna lens and to form a feed support boom utilizing the canister as part of the antenna structure. The canister is connected to the ring and support boom in the deployed state by the expandable trusses. A fully automatic system is included for deploying the antenna and for holding the antenna structure in its deployed state. By adding a second (back) boom and reflector screen, a paraboloidal antenna is formed. In a second embodiment, utilizing the same storage and deployment principle but with panel sets which are triangular in cross-section, when deployed, either an offset (asymmetrical) paraboloidal or a feed horn type antenna structure is formed. In another embodiment of the invention, utilizing the same principle and with panel sets which are triangular in cross-section, when deployed, a solar panel array is formed. Also disclosed is a foldable truss geostationary platform and package for transfer into a geostationary orbit. Finally, an alternate mechanism is disclosed in the form of a pantograph for deploying panel sets to form a truss.

Direct and diffused solar radiation collector

Abstract: A high concentration solar energy collector is provided which collects diffused solar radiation as well as direct solar radiation. A reflector focuses direct radiation onto a first collector and reflects a substantial portion of the diffused radiation onto a second collector positioned near the focus of the reflector.

Parabolic focusing apparatus for optical spectroscopy

Abstract: An accessory for use in the sample region of a spectrometer is disclosed which combines a matched pair of off-axis paraboloid reflectors having their focii optically imaged on the sample (either imaged at a common point or at two points which are optically imaged on each other) and having relative locations and orientations such that each ray of radiation strikes the two reflectors at points on the reflectors having approximately the same focal lengths. This arrangement involves the use of collimated optical beams into and out of the accessory. The accessory may function as a transmission-type accessory, in which the radiation passes through the sample, or as an internal reflectance accessory, in which the radiation passes through the sample holder but is reflected by the sample. The focal length relationship set forth is accomplished by having the "back-to-back" paraboloid reflectors, i.e., their reflecting surfaces face in substantially different, preferably opposite, directions. A further aspect is the incorporation of means for adjusting the position of at least one of the paraboloid reflectors along a first line parallel to, and along a second line perpendicular to, the axis of the collimated optical beam reflected by the position-adjustable reflector.

Reflector-coupled fluorescent solar collector

Abstract: The present invention provides a system for the collection of electromagnetic radiation and the transmission of that radiation to a point of use. In its simplest sense, an apparatus for the collection and transmission of electromagnetic radiation comprises a cylindrical fluorescent fiber, at least one end of which is optically coupled to an optical wave guide, and means for reflecting solar radiation impinging over a relatively wide area onto said cylindrical fluorescent fiber. Preferably, a compound parabolic mirror is employed for reflecting incident solar radiation onto the optical fluorescent fiber.

Panoramic zoom lens assembly

Abstract: A panoramic zoom lens assembly of the type including a reflector lens spaced from the image plane of an optical recording device such as a film camera or video camera is disclosed. The zoom lens assembly includes a cylindrical housing having a transparent sidewall portion and an opaque sidewall portion with a reflector mounted in optical communication with the transparent sidewall zone. The reflector is provided with a symmetrical, reflective surface of revolution the axis of which is transverse to the image plane. An annular, objective lens assembly is mounted within the housing in a fixed position surrounded by the opaque housing sidewall portion. An intermediate annular lens is mounted within the housing for reciprocal movement along the reflector axis between the objective lens and the image plane. Displacement of the movable annular lens varies the focal length of the overall lens assembly. In a preferred embodiment, a third annular lens is mounted in a fixed position between the movable annular lens and the image plane whereby the assembly can be mounted directly onto a camera housing.

Surgical lamp characterized by having an improved reflector

Abstract: A surgical lamp includes a thermoplastic reflector which reflects visible light but passes infrared radiation. The reflector is fabricated from molded polyetherimide plastic resin. A dichroic coating is vacuum deposit directly upon the front surface of the reflector.

Solar reflector panel

Abstract: A solar reflector panel includes a glass reflector element held by a thermoset plastic backing. The backing is molded around the reflector element to provide lips to lock the element in place on the backing.

Reflector antenna fields--An exact aperture-like approach

Abstract: A new computational approach is presented which allows fast analysis of radiation from large reflector antennas. For an aperture a Fourier transform (FT) relationship does exist between far-field and aperture distribution. Accordingly, the far field can be exactly reconstructed from the knowledge of approximately one sample per lobe (Shannon-Whittaker theorem applied at Nyquist rate). The finite reflector curvature introduces an extra factor in the radiation integral so that the radiation integral is no longer a FT. In order to overcome this difficulty a new pseudosampling expansion, which explicitly takes into account the extra factor, is developed. For parabolic reflector the sampling functions are related to the Fresnel integrals, and the far field can be exactly reconstructed in terms of aperture far-field samples, which can be computed using the fast Fourier transform (FFT). Numerical computations and error analysis show the excellent performance of the method, which can be generalized to deal with arbitrary reflector surfaces and near-field evaluation.

Method and apparatus for the interferometric wavelength measurement of frequency tunable C.W. lasers

Abstract: The invention relates to a method and an apparatus for measuring the wavelength of an object beam of electromagnetic radiation generated from a first source by comparing with a reference of known wavelength generated from a second source A fringe-counting Michelson-type interferometer is used, having a stationary arm and a variable arm and includes a planar beam splitter a planar beam mixer, a planar reflector in the stationary arm, and a movable retroreflector in the variable arm. Prior to moving the retroreflector the reference and object beams are aligned to provide a flat interference pattern. The portions of the reference and object beams in the moveable arm are directed to and reflected by the retroreflector off center thereof. The portions of the reference and object beams in the stationary arm have an angle of reflection α at the reflector. The beam mixer is situated relative to the beam splitter such that the plane of the beam mixer is angularly inclined with respect to the plane of the beam splitter by an angle equal to α. Parallelism of the second beam portions with one another in the variable arm of the interferometer is automatically provided as a result of the alignment of the reference and object beams to a flat interference pattern, without optical feedback of the beams to their respective source and parasitic diffraction effects by the retroreflector.

Collapsible parabolic reflector

Abstract: A portable, lightweight, folding parabolic reflector antenna for reception of microwave signals includes an axial wave guide tube which constitutes the main structural supporting member of the antenna, a ten to fifteen foot diameter dish mounted to the wave guide and a sub-reflector supported at the forward end of the wave guide. A low noise amplifier may be mounted to the rear end of the wave guide for amplification of the received signals. The folding dish includes a pre-formed dished reflector of pliable material supported by a radial framework of normally straight resiliently flexible spokes of tapering cross section. The spokes are pivotable by a lever system between a folded axial position and a deployed radial position. The normally straight spokes are stressed upon deployment by a perimeter cable to a curvature of the pliable dish such that the spokes and the dish are curved independently of one another and operate to correct deviations in the desired curvature of each other to thereby obtain a precisely repeatable dish curvature through many folding-unfolding cycles. A method of assembly of the folding reflector is disclosed as well as alternate embodiments of lightweight curved reflectors.

Inherent spectrum-splitting photovoltaic concentrator system

Abstract: A solar energy splitting photovoltaic concentrator system that includes a first reflector that concentrates and directs sunlight to a high energy bandgap first photovoltaic array that absorbs and converts into electricity high energy photons. A second reflector formed integrally with the first photovoltaic array concentrates and reflects low energy photons back through the first photovoltaic array, which is transparent to the low energy photon, to a low energy bandgap second photovoltaic array that absorbs and converts the low energy photons.

Solar power satellite

Abstract: A solar power satellite (30) includes a truss structure (32) having a plurality of independently controlled solar power modules (34) mounted to one face of the truss structure. The solar power satellite is constructed in orbit by first forming and then assemblying component beam members (50, 52) to the truss structure. The solar power modules (34) are constructed on a fabrication and assembly station (36) movably attached to the truss structure and are then attached to the truss structure. The solar power modules (34) include a primary reflector (200) having a substantially parabolic curvature in cross section. A collector-radiator (202) is mounted on the primary axis of the primary reflector. The cross-sectional configuration of the collector-radiator (202) approximates a flattened inverted S-shape whereon the radius of curvature decreases as the curve approaches both its center and its end furthermost from the primary reflector (200). The primary reflector (200) is contoured to reflect sun light onto the collector-radiator structure (202). The collector-radiator structure includes a plurality of spaced radiant energy converting cells (450 ). A plurality of light reflective fins (452) are positioned between the converter cells. Each fin is thermally and electrically connected to converter cells on each side thereof. The fins provide radiant cooling of and series electrical connection between the converter cells. The fins also serve as a secondary reflector for concentrating sun light from the primary reflector onto the converter cells.

Reflector for uniformly illuminating an area, particularly a film window of a film or slide projector, and reflector lamp

Abstract: To provide for essentially uniform illumination throughout the area, for mple the film window of a film or slide projector, the reflector has at least two contours which form a reflector system, each contour being rotation-symmetrical with respect to the optical axis of the total system. The generatrices of the contours follow conical sections. The reflector is divided into zonal regions, with successive zonal regions lying on different contours. For example, two conical contours can be used, the contour of one conical section being such that spot illumination results, and the contour of the other conical section being such that a saddle-tight illumination is obtained so that the overall light output throughout the window is essentially uniform (see the additive of FIGS. 3a and 3b, as shown in FIG. 3c).

Data link using integrated optics devices

Abstract: A transmission link is established between remote electrical transducers, e.g., underwater, and a monitoring receiver, e.g., shore-based, over an optical fiber link using integrated optical waveguides. Optical directional couplers with absorber and reflector elements incorporated in the waveguides at respective terminals of the transmission link permit the injection of light into the fiber at the monitoring terminal and the modulation of reflected light at the transducer terminal in accordance with an electrical signal from the transducer. No electrical energy then needs to be transmitted between the monitoring and transducing terminals of the transmission link. The link itself is thus light in weight and free of electrical currents subject to electromagnetic interference.

Operating room light

Abstract: To permit adjustment and ready removal of a halogen lamp from an operating room light so that the halogen bulb (3) can be positioned with respect to a dome-shaped reflector (1) to control the light distribution therefrom while being readily removable for bulb replacement and cleaning, a pivot arm (5) is hinged at a circumferential point to the outer circumference of the reflector (1) and held in horizontally extended position across the reflector by a latch (16, 20; 18, 19, 19'; 21, 27). The other end of the latch is in engagement with a vertically positionable adjustment sleeve or rod (7) to adjust the position of the latch arm, and hence of the lamp bulb (3) with respect to the apex of the reflector (1) by pivoting of the pivot arm (5) about its pivot point (6) adjacent the circumference of the reflector. A plurality of such lamps may be combined in a common housing (H), and adjustment can be carried out conjointly, for example by a drive (11, 23) common to all the adjustment elements.

Infrared thickness measuring device

Abstract: A device for measuring the thickness of a thin film or the like is provided using infrared rays. A source of infrared rays is positioned on one side of the film. A disk with two apertures is rotatably mounted between the infrared source and the film, with band-pass filters positioned over the apertures in the disk. A concave hemispherical reflector with a reflector surface facing the film is positioned between the infrared source and the film. A hole is formed in the center of the concave reflector through which the infrared rays pass. A convex reflector is positioned between the film and the concave reflector and has a reflecting surface facing the concave reflector. A light collecting guide with a photoelectric sensor is positioned on the opposite side of the film from the infrared source for measuring the intensity of the infrared rays.

High intensity reflector lamp

Abstract: A reflector lamp comprises an arc discharge tube disposed at about the focus of a parabolic reflector. The arc tube is supported by two lead-in support wires which extend through the back of the reflector. The external ends of the lead-in support wires are secured in a stabilizer support which is adhesively bonded to the back of the reflector.

Curved reflector with adjustable focal length

Abstract: A curved reflector (10) of electro-magnetic radiation formed of an elastic, reflective membrane (14) which utilizes a partial vacuum to provide the curvature to the membrane (14) and an adjustablevalve (20) to vary such curvature, and therefore the focal length of the reflector (10). The valve (20) comprises a central aperture in the membrane (14) and a body adjustably mounted above the aperture with a flow restricting surface thereon which overlies the aperture.