Showing papers on "Reflector (antenna) published in 1989"

Surface plasmon resonance sensors

Abstract: A surface plasmon resonance (SPR) sensor is adapted for biochemical and similar testing on large area samples such as the gel of an electrophoresis apparatus. The gel is sandwiched between a pair of plates. One of the plates is of transparent material and, sandwiched between itself and the gel is a metal layer of a mosaic of silver dots. Light from a source is directed via a reflector and undergoes total internal reflection at the interfacce between the transparent plate and metal layer. The reflected light is passed via another reflector to a light detector. The equipment is arranged so that SPR occurs at the metal layer, which resonance is critically dependent upon the refractive index of the gel. The structure including the light source and detector, together with reflectors is caused to scan across the gel surface to enable a two-dimensional representation of the changes in refractive index across the gel to be built up. This enables the progress of sequencing to be monitored.

Head-up display apparatus for automotive vehicle

Abstract: In a head up display apparatus for an automotive vehicle including a projector unit disposed at the ceiling of the automotive vehicle to project display images and a half-mirror reflector unit for reflecting the projected display images to the driver, the height of the half-mirror reflector unit and the angular position of the projector unit are automatically adjusted according to vehicle speed, so that virtual display images can be appropriately seen by the driver ahead of the half-mirror reflector unit along the driver's eye direction variable according to vehicle speed, by use of a relatively small half-mirror reflector unit.

Analysis of second-order gratings

Abstract: The results of an analysis of second-order gratings used as distributed Bragg reflectors in surface-emitting lasers are presented. The gratings provide reflection, output coupling, and power transmission to other gain segments for purposes of injection locking. The analysis determines these quantities for arbitrary-shaped grating teeth and includes the presence of a substrate reflector to reduce the radiated power in that direction. The reflector is shown to be effective, but only if it can be precisely positioned. Examples illustrating variations in dimensions, tooth shapes and heights, waveguide loss, and detuning are included. Second-order, square gratings, whose conventional coupling coefficient is identically zero, exhibit substantial reflectivity which is primarily produced by the radiation reaction. The analysis also forms the basis for calculating the far-field grating coupled radiation patterns. >

Solar concentrator - radiator assembly

Abstract: A combined solar concentrator and radiator assembly (10) is provided in a relatively lightweight and compact geometry adapted particularly for use in electrical power generation systems in space. The solar concentrator - radiator assembly comprises a solar reflector of the Cassegrain type having primary and secondary reflelctor surfaces (14) and (26) for concentrating incident solar ration upon a thermal powered generator unit (16). The primary reflector surface (14) is formed on one side of an array of interleaved panels (30) adapted for movement between a compact stowed profile to fit within the cargo bay of a transport vehicle, and an extended deployed configuration. The reverse sides of these panels define a space radiator of extended surface area connected to the generator unit (16) by heat transfer members such as heat pipes (34) for purposes of dissipating excess heat to the surrounding space environment.

A method for producing a shaped contour radiation pattern using a single shaped reflector and a single feed

Abstract: Eliminating the corporate feed network in shaped contour beam antennas will reduce the expense, weight, and RF loss of the antenna system. One way of producing a shaped contour beam without using a feed network is to use a single shaped reflector with a single feed element. For a prescribed contour beam and feed, an optimization method for designing the reflector shape is given. As a design example, a shaped reflector is designed to produce a continental-United-States (CONUS) coverage beam. The RF performance of the shaped reflector is then verified by physical optics. >

Optical emission device

Abstract: An optical emission device with an emitter semiconductor chip and a cover intended to be suitable for backlighting areas, the device having a comparatively low structural height and low packing density. The cover has a light aperture formed using a convex and concave lens for radiating light in a solid angle of maximum size. This device can also be used in combination with an additional external reflector and diffusion screen.

Universal solar concentrator panel

Abstract: A solar concentrator device has a solar energy receiver and a solar energy reflector including a plurality of individual panels turnable about two mutually perpendicular axes so that the panels in one row are jointly turnable about a first axis, the panels in the same row are turnable also relative to two further axes

Alignment acquiring, optical beam communication link

Abstract: A pair of remote non-cooperating, optical beam transceivers are disposed so that optical alignment between them is possible. A controller selectively causes one of the transceivers, while acquiring a communication link, to operate in a search mode, and the other to operate in a stare mode. Each transceiver has an optical axis and retro-reflects all incident beams which are not substantially aligned with the axis but does not reflect incident beams aligned with the axis. Each transceiver includes an axis-aligned beam transmitting source, a detector of incoming axis-aligned beams, a pointer for aiming the axis anywhere within a hemispherical range while searching for the other transceiver, a component which distinguishes between a retro-reflection of a transmitted beam and an incoming beam from another such transceiver, a sensor for quantitatively measuring the power of retro-reflected beam, a controller for moving the axis in an abbreviated search for a direction in which the power of a retro-reflected beam is maximum, and a beam tracker for maintaining boresight alignment once the transceivers' optical axes are aligned. Preferably, each transceiver includes a matched pair of reflecting telescopes rigidly mounted with their optical axes precisely aligned, one each for transmitting and one for receiving optical beams. Each telescope should include a primary reflector, a subreflector with a Cassegrainian focus behind the primary reflector, and a retro-reflector behind a vertex aperture in the primary reflector.

Multichannel cavity laser

Abstract: A switchable multichannel external cavity injection laser incorporates a diffraction grating between a linear array of n reflectors and a common reflector to define a set of n optical cavities having different frequency bands. Each of the (n+1) reflectors is provided by the optically distal end of an associated semiconductor laser amplifier whose optically proximal end is arranged to be substantially non-reflective.

Three dimensional display system

Abstract: A system that is able to display an object in three dimensions and an accompanying method for use therein. Specifically, through this system, a three-dimensional image is displayed as a series of segments, e.g. line segments, formed by intersecting those surfaces of an object that are visible to a viewer with a sequence of pre-defined parallel helical surfaces taken through the object, with substantially the same pitch and axial orientation as that of a rotating helical reflector. Each dot in a resulting segment is then projected through both a focusing lens and an anamorphic lens onto a spatially corresponding portion of the rotating helical reflector. The anamorphic lens, which rotates in unison with the helical reflector, ensures, in conjunction with the focusing lens, that each dot will be focused on a given point along the reflector. By painting each such segment on a different portion of the reflector, the reflector, as it rotates, will sweep out a focused displayed volume. As a result and due to the persistence associated with human vision, a three-dimensional self-radiant "ghost-like" image of the object will appear to be displayed about the central (longitudinal) axis of the reflector. As fewer intersecting segments are painted on each rotation of the reflector, the image will increasingly appear as a "wire-frame" outline of the contours and edges of the object. However, as the number of such segments painted on the reflector increases per each rotation thereof, the three-dimensional image of the object will increasingly appear to "fill in". The displayed image contains appropriate visual information, such as stereoscopic, parallax and focus affects, such that it provides a relatively accurate three-dimensional depiction of the object.

Radiation sensor for monitoring a body condition

Abstract: An electromagnetic sensor including an emitter (12, 18), a detector (14, 36) and a reflector (26). The emitter is on the upper portion of a housing (10) and the detector is in the lower portion of the housing. The emitter faces the opposite direction from the detector. The sensor is adapted to be placed against the skin (28) of a patient, with the detector portion of the housing in contact with the skin. Also provided is an overlay (24) holding the reflector. The reflector redirects the electromagnetic radiation emitted by the emitter toward the skin. The overlay is of sufficient size to cover the area above and around the emitter and detector, while holding the reflector spaced from the opposite to the emitter. Also disclosed is a method comprising the steps of emitting electromagnetic radiation in a direction away from the skin, reflecting that radiation toward the skin, permitting some of that reflected radiation to pass through body tissue where some is absorbed, and detecting the radiation emanating from that tissue.

Automated vehicle control

Abstract: In a guidance system for guiding an automated vehicle around an area such as a warehouse, a scanning laser beam from a source mounted on the vehicle impinges upon reflectors located around the area. Each reflector incorporates an optical code which identifies that reflector. Laser light reflected back to the vehicle from the reflectors is used to control the movement and heading of the vehicle. The area is divided notionally into a number of equal sub-areas of predetermined dimensions, each having at least two differently-coded reflectors. The vehicle is first moved to a position from which it can scan initialization reflectors located at selected initialization positions. The navigation system determines the initial position of the vehicle relative to the initialization reflectors and, during subsequent movements of the vehicle around the area, measures the distances and directions travelled by the vehicle from the initial position so that the navigation system can determine in which sub-area the vehicle is located at any instant. Because the system always knows in which sub-area the vehicle is located, it is not necessary for every reflector to have a unique code, so some duplication of codes around the area can be tolerated, thereby increasing the number of available reflectors for a given number of code elements.

Plate antenna with double crossed polarizations

Abstract: The radiating portion of the antenna is formed from two similar radiating doublets (1,3; 2,4) which are located in a single plane and are orthogonal, with the slots between driven elements of the doublets crossing one another at the center (C) of the unit antenna. The two doublet modules (1,3; 2,4) are associated with the central conductors of three-plate lines which are orthogonal, with their extensions crossing one another beneath the center (C) of the antenna. Each three-plate line consists of the plates (1,3; 2,4) of a doublet, on the one hand, a reflector, on the other hand, and between the plates and the reflector, the central conductor. The reflector is common to the two doublets.

Broad-band high-directivity antenna

Abstract: This Yagi-Uda-type antenna includes also a sleeve embracing the dipole. The sleeve may be a closed cylindrical element surrounding the dipole or it may comprise a pair of discrete elements forming an "open sleeve". The dipole, sleeve, reflector, and director elements may be in filamentary form, or they may be fabricated from stripline.

Compensation of reflector antenna surface distortion using an array feed

Abstract: Various aspects of reflector surface distortion compensation are explored by first assuming the reflector distortion is given and then designing the compensating feed array. The sensitivity of boresight directivity to changing surface distortion parameters for fixed feed-array geometries is examined. It is found that feed array compensation is feasible only for distortions with low spatial frequency content, such as those distortions induced by thermal and gravitational effects. The optimum directivity methods for determining element excitation is found to yield slightly better values of directivity than those for the conjugate field matching (CMF) technique. However, the CFM technique has, in general, much lower sidelobe levels and lends itself to simple realization in hardware. In view of these results, distortion compensation using an array feed is concluded to be a reasonable approach to improving antenna performance for large, space-based reflector antennas that are not easily accessible for tuning and have time-dependent surface distortions. >

Talbot cavity diode laser with uniform single-mode output

Abstract: A diode laser of the type having an array of laser emitters in a Talbot cavity in which edge reflectors are added to enhance feedback to edgemost emitters. In one embodiment, a transparent slab with reflectively coated sides is present between the phase plane of the emitted light and the Talbot cavity reflector. The phase plne is defined by a lenticular array placed a focal length in front of the laser emitters. In another embodiment, the Talbot cavity reflector has an increased reflectivity toward its edges. In all embodiments the Talbot cavity reflector is preferably spaced a distance na 2 /λ from the phase plane, where n is a positive integer, a is separation between adjacent emitters and λ is the wavelength of emitted light. An integrated embodiment has the array and cavity reflectors defined ina single semiconductor body divided into active and ransparent region. Side mirrors are etched into the semiconductor body. The laser array may also be extended to two dimensions with individual lasers or laser bars fiber coupled to a lens surface, with an edge reflector and Talbot cavity reflector coated on an otherwise transparent slab.

Automatic tracking type measuring apparatus

Abstract: A reflector provided on a land is automatically collimated in such a way that it always comes to the center of the field of view of an automatic tracking type measuring apparatus provided on a platform. When the platform moves vertically or horizontally in this state, the reflector moves within the field of view. Then, a drive signal is supplied to a servo system to cause the reflector to come to the center of the field of view. Based on data measured by the apparatus, the platform is positioned.

Single-mode properties of distributed-reflector lasers

Abstract: The fundamental properties of a distributed-reflector (DR) laser, consisting of an active section and a passive distributed reflector section, are theoretically investigated. The DR laser, in principle, has the properties of high efficiency and high-power performance in dynamic-single-mode operation, thus eliminating the problems of low device efficiency in DFB (distributed-feedback) lasers and low output power in DBR (distributed Bragg reflector) lasers. The effective length of a DR including gain and loss, is introduced and is applied for the analytical determination of the lasing condition. The conditions required for dynamic-single-mode operation with one-facet output are given in terms of the propagation constant difference between the active and passive regions related to the coupling coefficient of the passive reflector. This condition is experimentally found to be attainable by utilizing a conventional fabrication process. >

Quasistatic Shape Adjustment of a 15-Meter-Diameter Space Antenna

Abstract: A 15 meter diameter Hoop-Column antenna has been analyzed and tested to study shape adjustment of the reflector surface. The Hoop-Column antenna concept employs pretensioned cables and mesh to produce a paraboloidal reflector surface. Fabrication errors and thermal distortions may significantly reduce surface accuracy and consequently degrade electromagnetic performance. Thus, the ability to adjust the surface shape is desirable. The shape adjustment algorithm consisted of finite element and least squares error analyses to minimize the surface distortions. Experimental results verified the analysis. Application of the procedure resulted in a reduction of surface error by 38 percent. Quasi-static shape adjustment has the potential for on-orbit compensation for a variety of surface shape distortions.

Propagation of electromagnetic waves of crossroads with a reflector inside a tunnel

Abstract: We analyzed the wave propagation characteristics of the crossroad inside a tunnel, using the boundary‐element method. To simplify, the tunnel structure is assumed to be two‐dimensional and the side walls to be lossy dielectrics. We could improve the radio communication characteristics between two cross tunnels by a tetragonal reflector placed at the center of the crossroad. The diagonal length of the proper reflector is about 10%–20% of the tunnel width.

Second-harmonic reflector type high-gain FET frequency doubler operating in K-band

Abstract: A high-gain FET frequency doubler with a second-harmonic reflector in the input circuit has been developed. The reflector position which gives maximum multiplication gain depends on line loss. The relation between multiplication gain and the reflector position varies with line loss. A K-band frequency doubler designed on this basis was fabricated, showing a multiplication gain of 6 dB. >

Integrated structural electromagnetic shape control of large space anatenna reflectors

Abstract: The requirements for extremely precise and powerful large space antenna reflectors have motivated the development of a procedure for static shape control of the reflector surface. A mathematical optimization procedure has been developed that improves antenna performance while minimizing necessary shape-correction effort. The control procedure is based on regulating electromagnetic (EM) performance in contrast to previous work, which is based on controlling the rms distortion error of the surface, thereby indirectly improving antenna performance. The application of the control procedure to a radiometer design with a tetrahedral truss backup structure demonstrates the potential for significant improvement. The results indicate the benefit of including EM performance calculations in procedures for shape control of large space antenna reflectors.

Antenna with positionable reflector

Abstract: A horn type microwave antenna includes a main reflector and sub-reflector that are supported in proper spaced relationship by flexidigit robotic manipulators, multisection arms that are capable of positional changes, whereby the supports may be changed in position responsive to the application of control voltages. At least a portion of the manipulators include piezo electric actuators, permitting rapid adjustment of the reflectors' position.

A novel frequency-scanned reflector antenna

Abstract: Theoretical and experimental results are presented for a frequency-scanned antenna composed of a line source and a frequency-scanned reflection grating that is shaped to a cylindrical reflector. The principle considering is to select the grating geometry such that the first higher-order diffracted wave propagates and serves as the frequency-scanned beam. An analytical solution for the cylindrical reflector geometry that gives a line focus is given. The grating structure considered consists of an array of dipoles placed over a ground plane. The design of the dipole grating for optimum blazing (i.e., for optimal power conversion from the incident wave to the diffracted wave) is discussed. For the theoretical analysis Floquet's theorem and the method of moments are used. >

Linear array antenna with e-plane backlobe suppressor

Abstract: An antenna comprising a linear array of active elements positioned in one or more rows. The back portion of the array is partially enveloped by a reflector. The reflector includes a backwall and at least one sidewall perpendicular to the backwall and extending forward of the backwall. In one embodiment of the invention, a single row of dipole radiators form the linear array. In a second embodiment of the invention, a row of folded monopoles mounted on an imaging ground plane form the linear array. The radiation pattern is directed forward of the reflector, the back radiation in the E-plane being suppressed by the sidewall of the reflector.

Reflector assembly for heating a substrate

Abstract: A reflector (15) for use in drying a substrate is disclosed, which houses infrared or ultraviolet lamps (12). The reflector (15) is designed to limit the path of light from each lamp (12) to mitigate interference from one lamp (12) to the next. The reflector (15) is cooled and the substrate is heated by convection.

Sonic tank inventory control system and method

Abstract: A system for measuring the level of a fluid in a tank comprises a plurality of reflectors positioned in the tank with the reflectors being a known distance from one another and a first reflector being an unknown distance from the top of the tank and an apparatus for producing and outputting a sonic signal and for receiving echoes from the plurality of reflectors and a surface of the fluid in the tank. The apparatus produces electrical signals representative of the received echoes. The apparatus includes a processor responsive to the electrical signals for, (i) calculating the distance between the apparatus and the first reflector, (ii) calculating the distance between a last reflector and the fluid surface, and (iii) determining the total distance from the apparatus to the fluid surface based on the distances calculated in (i), (ii), and the distance between the first and last reflectors.

Luminaire having a lensed reflector system for improved light distribution control

Abstract: A lensed reflector system for a luminaire produces a specular beam of reflected light to provide a degree of directivity to an otherwise non-directive reflector surface. The lensed reflector system is formed by a prismatic lens material, such as a Fresnel lens, overlaying a reflector substrate having, in one aspect of the invention, a diffuse reflecting surface. The combination of the diffuse reflector and prismatic lens, together with the positioning of the reflector system in relation to the luminaire's light source, provides a reflector system which uniquely exhibits both diffuse and specular reflection characteristics depending on the angle at which the reflector system is viewed. The lensed reflector system of the invention can suitably be used in indirect lighting systems employing compact fluorescent lamps for increasing the spread of light from the fixture onto adjacent wall surfaces. The invention also comtemplates a lensed reflector system having a specular reflector substrate wherein a beam of enhanced specular reflectance is produced from an otherwise normally specular reflecting surface.

Adjustable light fixture

Abstract: A light fixture (10) adjustable in focus and/or beam direction. Light fixture (10) is of the "vertical" or "downlighting" type, and preferably includes a bulb/lens assembly (16) mounted atop a relatively short post (14). Bulb/lens assembly (16) includes a lens (30) which rotatably carries a cap (72). Inside lens (30) and beneath cap (72) is a bulb (42) and a reflector assembly (48). Reflector assembly (48) includes a reflector holder (50) having a plurality of outwardly-extending posts (70) which are first received by vertical slots (46) in lens (30) and finally by cam grooves (80) in cap (72). Rotation of cap (72) relative to lens (30) causes cam grooves (80) to act upon posts (70) to move reflector assembly (48) relative to bulb (42). Reflector assembly (48) can be moved vertically relative to bulb (42) to adjust the width or focus of the light beam; and/or tilted vis-a-vis bulb (42) to adjust the direction of the light beam.

Gaussian beam techniques for illuminating reflector antennas

Abstract: Simple design procedures are presented for use when a Gaussian beam is used to illuminate a classical reflector antenna. Displacement of the location of the beamwaist toward the focusing element in the case of electrically small antennas where the aperture is in the near field of the feed was calculated together with modification of the required beamwaist radius. Dual reflector antennas were discussed and design procedures appropriate for systems with large and small focal length to diameter ratio developed. Cases where a reflector or subreflector is electrically small, or in the near field of a feed, are readily treated. For elliptical beam antennas, a simple illumination system using only a scalar horn and a single cylindrical lens can generally be found; this has no ray optics analogue. A configuration of this type is discussed, with a practical case study of a 28-by-80- lambda elliptical Cassegrain antenna operating at a wavelength of 3 mm. The design process for designing the feed system is discussed in detail. Despite the small size and relatively large aperture blockage, an aperture efficiency of 0.48 was measured, which compared quite well with the expected efficiency of 0.53, thus verifying the validity of the Gaussian beam design approach. >