Showing papers on "Reflector (antenna) published in 2004"

Solar energy utilization unit and solar energy utilization system

Abstract: A solar energy utilization unit comprises a solar radiation concentrating optics and a solar radiation receiver including a first receiver component designed to convert into electric energy radiation in a first part of the solar spectrum, and a second receiver components designed to convert into electric energy radiation in a second part of the solar spectrum which is different from said first part. The solar radiation concentrating optics comprises a concave primary reflector adapted to reflect incident solar radiation towards the secondary reflector, and a convex secondary reflector adapted to reflect radiation in the first part of the solar spectrum into the first receiver component and also to transmit radiation in the second part of the solar spectrum into the second receiver component. The primary reflector is formed with a centrally disposed opening, via which the first receiver component is adapted to receive the radiation reflected by the secondary receiver. The primary receiver may have central and peripheral components, wherein the central component is made of a material which withstands heat better than the material from which the peripheral component is made.

Array antenna device and its control method

Abstract: PROBLEM TO BE SOLVED: To provide an array antenna device which is simple in structure, small in size and light, and can control a directional property on a vertical plane, and its control method. SOLUTION: The array antenna device comprises a plurality of non-exciting elements provided away from an exciting element for transmitting/receiving radio signals just for a predetermined distance, and variable reactance elements connected between the exciting element and the non-exciting elements, and each variable reactance element is connected between at least a pair of non-exciting elements in the plurality of exciting elements. In this case, the exciting element and the plurality of non-exciting elements are juxtaposed on one straight line, thereby configuring a colinear array antenna. Reactance values to be set to the respective variable reactance elements are changed to operate each non-exciting element as a waveguide or a reflector, so that the directional property of the array antenna is changed. COPYRIGHT: (C)2005,JPO&NCIPI

Secondary reflector for SHF antennae of the cassegrain type

Abstract: The invention concerns the secondary reflectors of SHF antennae of the Cassegrain type. It consists of providing the secondary basic reflector (103) of this antenna with a first circular ring (104) in the shape of a cylinder directed toward the main reflector, and a second ring (105) in the shape of a circular crown fixed to the end of the cylinder, and projecting outward from the latter. These rings are made from a conducting material. The length of the cylinder and the width of the crown are of the range of one quarter of the average wavelength for which the antenna is dimensioned. This enables the “overspill radiation” of the secondary reflector to be reduced considerably, and therefore allows the dimensions of the antenna to be reduced significantly for equivalent performance.

GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector

Abstract: A GaInN light-emitting diode (LED) employing an omni-directional reflector (ODR) is presented. The ODR consists of a RuO2 ohmic contact to p-type GaN, a quarter-wave thick SiO2 low-index layer perforated by an array of micro-contacts, and an Ag layer. Calculations predict a 98% angle-averaged reflectivity at λ=450 nm for an GaN/SiO2/Ag ODR, much higher than that for a 20 period Al0.25Ga0.75N/GaN distributed Bragg reflector (49%) and an Ag reflector (94%). It is shown that the RuO2/SiO2/Ag ODR has higher reflectivity than Ni/Au and even Ag reflectors, leading to a higher light extraction efficiency of GaInN LEDs with ODR. The electrical properties of the ODR-LED are comparable to those LEDs with a conventional Ni/Au contact.

Led lighting assembly with improved heat management

Abstract: The present invention provides a lighting head assembly that incorporates a high intensity LED package into an integral assembly including a heat sink and circuit board for further incorporation into other useful lighting devices. The present invention primarily includes a heat sink member that also serves as a mounting die and a reflector cup into which the LED package is mounted. The circuit board is placed behind the reflector cup and includes riser members that extend through holes in the rear wall of the reflector cup to facilitate electrical connections to the leads of the LED. This particular means for assembly allows the reflector cup and circuit board to cooperate to retain the LED package, provide electrical and control connections, provide integral heat sink capacity and includes an integrated reflector cup. In this manner, high intensity LED packages can be incorporated into lighting assemblies through the use of the present invention by simply installing the present invention into a housing and providing power connections thereto.

Wavelength-selective reflector based on a circular array of coupled microring resonators

Abstract: We propose and analyze a novel type of wavelength-selective reflector for planar lightwave technology based on a circular array of coupled microring resonators. Narrow-band reflection peaks can be achieved without the need for additional complex lithography and processing steps. The ring resonators also allow for simple and wide-range tuning of the reflection peak.

Optical Design of Two-reflector Systems, the Monge-Kantorovich Mass Transfer Problem and Fermat's Principle

Abstract: It is shown that the problem of designing a two- reflector system transforming a plane wave front with given in- tensity into an output plane front with prescribed output in- tensity can be formulated and solved as the Monge-Kantorovich mass transfer problem.

Wireless communication device with variable antenna radiation pattern and corresponding method

Abstract: A communication device (10) and a corresponding method are arranged for changing the radiation pattern of an antenna (14), where the radiation pattern of the antenna (14) is set to a half-space pattern if the communication device (10) is in close proximity to an object. A reflector (18) is activated to produce the half space radiation pattern. The reflector (18) is deactivated to produce the full space pattern. A switching device (26) determines the state of the reflector (18). A sensing and control device (23) controls the state of the switching device (26).

Slow-light enhancement of radiation pressure in an omnidirectional-reflector waveguide

Abstract: We study the radiation pressure on the surface of a waveguide formed by omnidirectionally reflecting mirrors. In the absence of losses, the pressure goes to infinity as the distance between the mirrors is reduced to the cutoff separation of the waveguide mode. This divergence at constant power input is due to the reduction of the modal group velocity to zero, which results in the magnification of the electromagnetic field. Our structure suggests a promising alternative, microscale system for observing the variety of classical and quantum-optical effects associated with radiation pressure in Fabry–Perot cavities.

Birefringent omnidirectional reflector.

Abstract: Anisotropic optical coatings offer unique polarizing properties, unmatched by conventional isotropic devices. Here we demonstrate the fabrication of a birefringent omnidirectional reflector, a type of photonic crystal, which exhibits complete reflection of radiation at 1.1 μm for all incidence angles and polarizations. The thin-film device was deposited from electron-beam evaporated silicon, with refractive-index variation arising from atomic-scale porosity created with glancing-angle deposition. Birefringence was found to enhance the performance of the device compared with its isotropic counterpart by enlarging the photonic bandgap region of omnidirectional reflection.

Surface-emitting semiconductor laser

Abstract: A surface emitting semiconductor laser includes: a substrate; a first semiconductor multilayer reflector of a first conduction type that is formed on the substrate and is composed of stacked pairs of relatively high refractive index layers and relatively low refractive index layers; a cavity region that is formed on the first semiconductor multilayer reflector and includes an active region; and a second semiconductor multilayer reflector of a second conduction type that is formed on the cavity region and is composed of stacked pairs of relatively high refractive index layers and relatively low refractive index layers. A cavity length of a cavity that includes the cavity region and the active region between the first semiconductor multilayer reflector and the second semiconductor multilayer reflector is greater than an oscillation wavelength.

Deployable antenna with 10-m maximum diameter for space use

Abstract: This paper describes a large deployable antenna which is used at L-, C-, and Ka-bands on an artificial satellite in space. The main reflector with 10-m maximum diameter is formed using the tensioned truss concept which was proposed by one of the authors. The mechanical structure of the antenna is briefly explained and a more detailed description given of the electrical design of the antenna and the verification method of electrical characteristics. This antenna was successfully launched and deployed in space in 1997 and is used for a Space VLBI mission.

Modular inflatable multifunction field-deployable apparatus and methods of manufacture

Abstract: An modular, inflatable, multi-function, field-deployable apparatus 600 having, in its preferred embodiments, an inflatable reflector apparatus 610 comprising a least one manufactured parabolic mirror made from a pressure-deformable reflective covering of an inflatable ring for focusing electromagnetic energy from radio frequency radiation (RF) through the ultraviolet (UV) radiation including solar energy for (1) heating and cooking, (2) electrical power generation, (3) enhancing the transmission and reception of radio signals, (4) enhancing vision in low-light environments, and/or (5) projection of optical signals or images. The device also has non-electromagnetic uses, such as the collection and storage of water, harnessing of energy from a fluid stream, and/or harnessing wave energy. A first main embodiment of the inflatable reflector apparatus 610 generally utilizes two pressure-deformable membranes, at least one of which is reflective. A second main embodiment utilizes a reflective membrane and a transparent membrane. In addition to the reflector apparatus 610, the modular apparatus 600 typically further includes modular assemblies to increase versatility, facilitate use, and/or enhance safety such as, for example, a modular support and orienting assembly 612, a separate support ring 614, a safety shield or cage 616, a focal point support assembly 618, a safety cover 620, a safety net or mesh 622, and a stabilizing assembly 624. Portability is enhanced by complete collapsing of the inflatable device.

Head-up display device

Abstract: A head-up display device having an excellent appearance, which has a simple structure and an excellent design upon both nonuse and use, is provided A cover having a shape equivalent to that of an aperture formed on an upper surface of a housing is attached on an upper surface of a retractable reflector The cover slides on the upper surface of the reflector cooperating with a retractable motion of the reflector, thereby performing the opening and closing action of the aperture When the reflector takes its falling-down posture, the reflector and its rotation shaft can be shielded from an eye range and the number of the parting lines can be reduced

High brightness light-emitting device and manufacturing process of the light-emitting device

Abstract: A light-emitting device comprises a multi-layer structure including one or more active layer configured to irradiate light in response to the application of an electric signal, a transparent passivation layer laid over an outmost surface of the multi-layer stack, a reflector layer laid over the passivation layer, and a plurality of electrode pads coupled with the multi-layer structure. In a manufacture process of the light-emitting device, the reflector layer and the passivation layer are patterned to form at least one opening exposing an area of the multi-layer structure. One electrode pad is formed through the opening of the reflector layer and the passivation layer to connect with the multi-layer structure.

Thermally controlled solar reflector facet with heat recovery

Abstract: A high concentration central receiver system and method provides improved reflectors and a unique heat removal system. The central receiver has a plurality of interconnected reflectors coupled to a tower structure at a predetermined height above ground for reflecting solar radiation. A plurality of concentrators are disposed between the reflectors and the ground such that the concentrators receive reflective solar radiation from the reflectors. The central receiver system further includes a heat removal system for removing heat from the reflectors and an area immediately adjacent the concentrators. Each reflector includes a mirror, a facet, and an adhesive compound. The adhesive compound is disposed between the mirror and the facet such that the mirror is fixed to the facet under a compressive stress.

Apparatus and method for using emitting diodes (LED) in a side-emitting device

Abstract: An LED having a predetermined direction of radiation is combined with a first and second reflector. The first reflector opposes the LED and has a predetermined direction of reflection. The direction of reflection of the first reflector opposes the direction of radiation of the LED. The second reflector has a predetermined azimuthal direction of reflection. The second reflector positioned relative to the first reflector to receive light from the first reflector and redirect the light into the azimuthal direction of reflection. The LED, first and second reflectors collectively comprise an illumination unit. A plurality of illumination units are axially stacked. In one embodiment of the stack, at least one illumination unit comprises an LED and second reflector of one illumination unit and a first reflector of an adjacent illumination unit in the stack of illumination units.

Scintillator assembly with pre-formed reflector

Abstract: A scintillator assembly with at least one scintillator pixel (202). A reflector (203) is preformed, and at least a portion of the scintillator material fits within the preformed reflector (203). The reflector assembly (203) may have a single pre-formed unit or a plurality of subassemblies, one or a plurality of which having been pre-formed prior to insertion of one or a plurality of scintillator pixels (202). The reflector assembly (203) may provide for the formation of intentional air gaps between one or a plurality of reflector walls and one or a plurality of scintillator pixels (202).

Optical system for a wide field of view staring infrared sensor having improved optical symmetry

Abstract: A wide-angle IR imaging system (1A) has an entrance aperture (40) for admitting IR from a scene and a dewar (4A) that contains a coldshield (3) that encloses a cooled IR detector (2) disposed at an image plane (2A). The dewar includes a dewar window (4), and an optical axis of the IR imaging system passes through the dewar window and the image plane. The IR imaging system further includes a plurality of uncooled optical elements (22, 24, 26, 28) disposed along the optical axis between the entrance aperture and the dewar window, and a plurality of generally annular reflector segments (18A, 18B) disposed around the optical axis betwen the dewar window and the entrance aperture. Each of the reflector segments has a reflective surface that faces the dewar window. An opening through an outermost reflector segment furthest from the dewar window defines an effective cooled aperture stop, or warm stop (20A) of the IR imaging system, and at least one of the optical elements (22) is disposed between the effective cooled aperture stop and another one of the reflector segments (18A) that is located nearer to the dewar window. In the preferred embodiment the at least one optical element, and the reflector segment that is located nearer to the dewar window, are comprised of a single monolithic body (31) that has a compound optical surface.

Fast Gaussian beam based synthesis of shaped reflector antennas for contoured beam applications

Abstract: A relatively efficient procedure is proposed, which combines a novel Gaussian beam (GB) approach for fast computation of reflector antenna radiation patterns with an iterative optimisation technique, to synthesise a shaped reflector surface for contoured beam applications. The GB approach employs relatively few Gaussian beams as electromagnetic basis functions to represent the field radiated by the feed; each of these GBs launched from the feed then reflects and diffracts from the reflector surface to yield the radiation field produced by the reflector antenna. Closed form expressions are used for calculating this GB reflection and diffraction; consequently, the reflector radiation pattern, which needs to be computed repeatedly in any iterative synthesis procedure, can be obtained in an extremely rapid fashion via the present GB method. In contrast, the conventional procedure, which requires a numerical integration of the currents induced by the feed over the large reflector surface to calculate the radiation field, is far less efficient and lacks physical insight. Furthermore, the GB approach is used in conjunction with a fast and convergent synthesis procedure which is developed via a modification of the usual steepest descent method (SDM) to ensure a more global reflector shaping optimisation and smooth contoured beam patterns. Numerical results are presented to validate the proposed approach.

Reflective Ag alloy film for reflectors and reflector provided with the same

Abstract: A reflective Ag alloy film for reflectors, which has excellent surface flatness and shows high reflectivity even under a heating environment and a reflector. The reflective Ag alloy film for reflectors has an average surface roughness of 2.0 nm or less and contains a rare earth element (such as Nd) in a content in the range of 0.1 to 3.0 at %, or further at least one selected from Au, Pd, Cu and Pt in a content in the range of 0.5 to 5.0 at %. The reflector comprises the above reflective Ag alloy film formed on a substrate.

Optical properties of elliptical reflectors

Abstract: Elliptical reflectors are widely used in illumination engineering as a means to concentrate the light of a source in the secondary focal plane. To collect as much light from the source as possible, the reflector must cover a wide angular range of the emitted radiation, hence forward and backward reflections on the reflector must be discussed and conditions for paraxial optics do not apply. We develop a framework of relations that describe the image of an extended source in the secondary focal plane of the ellipsoid. After deriving basic relations between object and image spaces, the propagation of rays depending of their origin and on their direction is investigated. As a result, the function and the aberrations of the reflector can be expressed in terms of an angular dependent magnification for longitudinal and lateral coordinates. With that, one cannot not only calculate luminance and illuminance distributions in the secondary focal plane in a straightforward manner, but can easily understand their properties and their dependence on ellipse parameters. On the basis of the developed relations, implications for the design of "elliptical" short arc high-intensity-discharge (HID) lamps for video projection are discussed.

LED luminaire with thermally conductive support

Abstract: A heat dissipating lamp is provided. The lamp includes a reflector, a lens cover, a support structure interposed between the reflector and the lens cover, and an LED mounted to the support structure. The lens cover includes a portion adjacent a peripheral edge of the reflector. The support structure includes a bridge.

Folded-Loop Antenna with a Reflector for Mobile Handsets at 2.0 GHz

Abstract: A folded-loop antenna with a reflector for mobile handsets at the 2.0-GHz band is analyzed, taking the effect of the human head into account. The reflector is arranged between the human head and the driver. The width and height of the reflector are chosen to be slightly smaller and larger than those of the driver, respectively. Based upon numerical investigations, this antenna is found to enhance radiation efficiency by 20% and reduce peak specific absorption rates (SARs) averaged over 1 g and 10 g of tissues by 70%–85%. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 272–275, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11350

Cleaning device for parabolic channel collector has absorber pipe and channel shaped reflectors whereby collecting device is provided on cleaning vehicle for collecting water falling from reflector and for returning water to water tank

Abstract: The cleaning device has an absorber pipe and a channel shaped reflector (10). A cleaning vehicle is movable along the parabolic channel collector and has a water tank (15) and a nozzle assembly following the reflector contour. A collecting device (16) is provided on cleaning vehicle for collecting the water falling from the reflector and for returning the water to the water tank.