Showing papers on "Reflector (antenna) published in 1993"

Dual polarized dual band antenna

Abstract: An antenna system is described including a reflector antenna, responsive to radio frequency signals at a first frequency, having a first reflector surface, a second reflector surface and a Cassegrain feed. The antenna system further includes an array antenna having a plurality of antenna elements responsive to radio frequency signals having a second different frequency, wherein a center element is in a common location with the feed of the reflector antenna. With such an arrangement, an improved dual band antenna system is provided. By providing the center element of the array antenna in a common location with the feed of the reflector antenna, a dual band radio frequency antenna system is provided which is more compact with improved radiation characteristics than known similar configured antennas.

74 nm wavelength tuning range of an InGaAsP/InP vertical grating assisted codirectional coupler laser with rear sampled grating reflector

Abstract: A vertical-grating-assisted codirectional coupler laser with rear sampled grating reflector (GCSR laser) combines single-mode operation over a very wide tuning range of 74 nm with a side-mode suppression of better than 30 dB over most of the wavelength span. The total tuning span is limited by the combined bandwidths of the active material gain curve and the envelope of the sampled grating reflection peak spectrum, while the tuning capacity of the directional coupler filter alone is estimated to be at least 140 nm. >

Multiple reflector concentrator solar electric power system

Abstract: Disclosed is a solar electric power system that utilizes multiple reflectors to concentrate sun light onto a panel of photovoltaic (PV) cells. The power system, consisting of multiple reflectors, mounted PV cells, and a heat dissipation component, is mounted on a tracker that keeps the system directed to the sun. A noteworthy feature of this system is its designed-in capability of being retrofitted with advanced reflectors, PV components, and heat dissipation components during the system's multi-year operating life. The common axes design feature of the system allows for low cost materials and manufacturing concepts. The system can operate on either a single or a dual axis tracker with active or passive cooling.

Concentrating and collecting optical system using concave toroidal reflectors.

Abstract: An electromagnetic radiation source, such as an arc lamp, is located at a point displaced from the optical axis of a concave toroidal reflecting surface. The concave primary reflector focuses the radiation from the source at an off-axis image point that is displaced from the optical axis. The use of a toroidal reflecting surface enhances the collection efficiency into a small target, such as an optical fiber, relative to a spherical reflecting surface by substantially reducing aberrations caused by the off-axis geometry. A second concave reflector is placed opposite to the first reflector to enhance further the total flux collected by a small target.

Nonimaging reflectors as functionals of the desired irradiance

Abstract: For many tasks in illumination and collection it is necessary that the acceptance angle vary along the reflector. If the acceptance-angle function is known, then the reflector profile can be calculated as a functional of it. The total flux seen by an observer from a source of uniform brightness (radiance) is proportional to the sum of the view factor of the source and its reflection. This allows one to calculate the acceptance-angle function that one needs to produce a certain flux distribution and thereby to construct the reflector profile. We demonstrate the method for several examples, including finite-size sources with reflectors directly joining the source.

Distributed reflector and wavelength-tunable semiconductor laser

Abstract: The distributed reflector includes a substrate and at least one optical waveguide formed on the substrate and having a refractive index larger than the substrate and at least one optical confinement layer having a refractive index smaller than the optical waveguide layer. A diffractive grating is formed in at least one layer constituting the optical waveguide. The diffractive grating has a structure of which at least one parameter defining optical reflectivity varies depending on its position, and is formed continuously for at least two periods, the period being approximately defined by the length of repeating unit region. The parameter may be pitch, coupling coefficient, bandgap composition, phase shift, etc. The semiconductor laser includes the distributed reflector which may be of a distributed reflector type or distributed feed back type and has distributed reflector regions and a phase adjustment region. Application of current or voltage to the refractive index of the active region or inactive region in which a diffractive grating is present or absent adjusts the refractive index thereof and enables coarse and fine adjustment of lasing wavelength.

Thin high efficiency illumination system for display devices

Abstract: An illumination system for a display device includes an array of cylindrical lenslets for imaging an adjacent array of different color monochromatic emitting phosphor stripes onto the display device. Also included is a microcollimator reflector for each stripe which partially collimates emitted light from each phosphor stripe with respect to at least one axis of the display. An edge-irradiated energy distributor plate efficiently distributes ultra-violet energy by total internal reflection to the phosphor stripes that act as scattering and absorbing centers for the ultra-violet energy.

Diffraction analysis of frequency selective reflector antennas

Abstract: A unified computational technique which allows the incorporation of the curved frequency selective surface (FSS) geometry in the computation of a dual-reflector-antenna radiation pattern is presented. The scattered fields from a illuminated FSS reflector are formalized using Huygens' principle in such a way that the 'reflecting' and the 'transparent' FSS subreflector cases are treated identically and the thickness of the FSS subreflector remains arbitrary. The analysis utilizes local surface coordinates to describe the reflection/transmission matrices of the FSS subreflector, assuming that these matrices are available. In most cases the local tangent plane may be used to approximate the plane of the FSS in the local coordinate surface of the reflector. The way in which the local curved coordinate system can be introduced in the diffraction modeling of FSS reflectors and its importance in accurately predicting the sidelobe and cross-polarization levels are demonstrated. Results of numerical simulations are presented for several FSS subreflector configurations. >

Enhanced performance aperture-coupled planar antenna array

Abstract: A flat antenna is disclosed which consists of a substrate having applied thereto an electrically conductive elements, or patches, in a pattern and a metal layer having a slot pattern aligned with the patches, as well as a distribution network mounted on both sides thereof a layer of foamed material. The antenna further includes a reflector consisting of a metal plate. The external surface of the antenna, consisting of a glass substrate surface, can easily be cleaned. Such an antenna can be manufactured inexpensively by using glass and a foamed material. The various patch patterns can be created by screen printing or metallization. The propagation pattern may be shaped as desired the antenna constructed according to the present invention.

Reflective type liquid crystal display device

Abstract: A reflective type liquid crystal display device in accordance with the present invention includes a reflector film having excellent polarization preservation properties and an anisotropic diffusing film for diffusing only the light polarized in a particular direction. The anisotropic diffusing film is composed of a complex of liquid crystal and a polymer and selectively diffuses incident light. If a liquid crystal layer composed of dichroic dye and liquid crystal is employed, it becomes possible to carry out high contrast display with the anisotropic diffusing film and the reflector film and to prevent reflections of nearby objects appearing on the screen. Similarly, if a liquid crystal layer composed of liquid crystal and a polymer and having a twist angle of orientation of the liquid crystal specified to be in a range of 40° to 50° between an insulating substrate and a reflector member is employed, and the reflector film possesses excellent polarization preservation properties, similarly to the above case a reflective type liquid crystal display device can be obtained which reflects no nearby objects on the screen and can carry out high contrast display.

Beam delivery system and method for corneal surgery

Abstract: An apparatus and method for delivering radiant energy beams onto an area of a cornea in a line focus to create a linear incisions. The radiant energy beams may be focused in a linear configuration onto the external surface of the cornea or onto intrastromal areas of the cornea of an eye to ablate the cornea in a radial slot, circumferential curved slot, or lenticular pattern, and thereby modify its curvature and refractive power. The apparatus includes an array of central reflectors and an assembly of peripheral reflectors. Each central reflector is associated with a respective peripheral reflector so that a beam reflected by the central reflector is intercepted by its associated peripheral reflector and is again reflected to precisely incise either external or internal areas of the cornea. Each peripheral reflector has a curved reflective surface to provide a line focus on the cornea, including both rectilinear and curvilinear line focus to create radial and circumferential curved incisions. In a modified embodiment, the assembly of peripheral reflectors and the array of central reflectors rotate to permit lathing of the cornea.

Reflector posts--signs of danger?

Abstract: Reflector posts are meant to increase optical guidance and help drivers see the road alignment ahead so that they can prepare for the driving task to come. It is often assumed that the additional visual cues provided by reflector posts also promote traffic safety. An experimental study on the effects of reflector posts was carried out on two-lane rural highways in Finland. On roads with 80-km/hr speed limits and relatively low geometric standards, the reflector posts increased driving speeds in darkness. The largest detected increases were 5 to 10 km/hr. The number of injury accidents in darkness increased by 40 to 60%. On roads with better geometric standards and 100-km/hr speed limits, the effects on driving behavior and accidents were small. The results indicate that reflector posts on narrow, curvy, and hilly roads can significantly increase driving speeds and accidents in darkness.

Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna

Abstract: A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.

Ambiguity in analysis of velocity and depth

Abstract: Velocity analysis methods generally involve an analysis of the traveltime moveout of seismic events. To investigate ambiguities for such methods, we can start with a simple single layer model and investigate the uncertainty in the estimation of velocity and reflector depths. This analysis will show that the velocity‐depth ambiguity is dependent on the offset‐depth ratio and on the accuracy of traveltime picks.

Means and method for highly controllable lighting

Abstract: A highly controllable way to light target areas includes primary reflector which generates a defined primary beam in association with a light source. The primary beam, or at least a portion of the primary beam, is directed onto a secondary reflector which generates a secondary beam to the target space. The secondary reflector can be configured in any number of contours, shapes, specularities, or other characteristics to alter and control the characteristics of the secondary beam.

Cylindrical-wave controlling, generating and guiding devices

Abstract: Designs for cylindrical-wave controlling, generating and guiding devices are disclosed, which include multi-cylindrical-layer reflector and anti-reflection for unguided cylindrical waves, and concentric-circle-grating waveguide reflector, directional coupler and distributed feedback structures for guided cylindrical waves. A multi-cylindrical-layer structure takes the form of cylindrical layers wrapped concentrically around a central rod. A grating waveguide structure takes the form of a slab waveguide in which one of the slabs has circular ridge-groove grating. Layer and ridge-groove spacings are critical to the functionality of these structures. Design rules are outlined. These structures are important components for cylindrical wave controls. Designs of narrow-linewidth and high-power surface-emitting semiconductor lasers using the grating reflectors and 90-degree couplers are also disclosed.

Reduction in the series resistance of the distributed Bragg reflector in vertical cavities by using quasi‐graded superlattices at the heterointerfaces

Abstract: Surface emitting optical devices with a vertical cavity have been investigated for applications in optical interconnections. To integrate these devices into a two‐dimensional array, it is necessary to improve the conversion efficiency from electrical power to optical power. To meet this requirement, the series resistance of the distributed Bragg reflectors that form the vertical cavity must be reduced. This article demonstrates the reduction in the series resistance of the distributed Bragg reflector by introducing quasi‐graded superlattices at the heterointerfaces. By using this structure, we obtain a low series resistance distributed Bragg reflector without compromising the high reflectivity. The mechanism of the reduction in the series resistance is studied and it is found that an increase in tunneling current leads to a decrease in the resistance. The dependence of tunneling current on doping concentration of the distributed Bragg reflector and the superlattice structure is also discussed.

An optical integrated circuit having light detector

Abstract: An optical integrated circuit (21) is disclosed. The optical integrated circuit (21) includes: a dielectric waveguide (23) having at least a waveguide layer (4) for transmitting light in a first direction (8); a first reflector (14) for reflecting the light in a substantially opposite direction (13) to the first direction (8), the first reflector (14) being formed on an end face of the waveguide layer (4); a grating coupler (6) having a grating for diffracting at least a part of the light in a second direction (10) which is different from the first direction (8), the grating coupler (6) being formed at a surface (18) of the waveguide layer (4); and a light detector (22) for detecting the diffraction light (10, 11, 15, 16), the light detector (22) being optically connected with the dielectric waveguide (23).

Microwave powered lamp having a non-conductive reflector within the microwave cavity

Abstract: A microwave-powered discharge lamp having a microwave cavity, a discharge lamp mounted within the cavity, a reflector for light emitted by the lamp mounted outside the cavity, and a non-conductive reflector mounted within the cavity for outwardly reflecting light emitted from the lamp.

Frequency tunable waveguide extended cavity laser

Abstract: A frequency tunable waveguide extended cavity laser formed with a laser diode, a channel waveguide comprising an electro-optic material, a frequency tunable Bragg grating reflector formed in or on the channel waveguide and a pair of conducting electrodes. The frequency of radiation produced by the frequency tunable waveguide extended cavity laser is adjusted so as to be at a desired frequency by applying a voltage to the conducting electrodes. The device further incorporates a waveguide nonlinear optical frequency converter to produce frequency convened radiation at a higher frequency. Feedback means are included for dynamically controlling the desired frequency so as to be at a frequency for optimum frequency conversion.

Dual reflector antenna with narrow broadside beam for omnidirectional coverage

Abstract: A new type of high gain omnidirectional antenna is presented, particularly suited for higher frequencies (e.g. milllimetre waves): it is obtained with an axially symmetric dual reflector system, fed with an unconventional feed with conical pattern. The feed radiated field, after reflection on the parabolic subreflector and on the conical main reflector, is uniformly scattered in the plane perpendicular to the axis of the system, with vertical polarisation and narrow vertical beamwidth.

Multi-zone illuminator with embedded process control sensors

Abstract: A multi-zone illuminator for processing semiconductor wafers is described which comprises a plurality of source lamps and dummy lamps embedded in the reflector side of a lamp housing. The source lamps are arranged in a plurality of concentric circular zones. The illuminator also comprises plurality of light pipes for receiving multi-point temperature sensors to measure the semiconductor wafer temperature and its distribution uniformity. A gold-plated reflector plate is attached to the bottom side of the lamp housing for reflecting and directing optical energy toward the wafer surface. The distance between the reflector plate and the wafer and the lamps and the wafer may be adjusted with the use of a spacial elevator and adaptor assembly. The multi-zone illuminator allows uniform wafer heating during both transient and steady-state wafer heating cycles.

AlGaInP visible resonant cavity light-emitting diodes

Abstract: Visible (670-nm) resonant cavity light-emitting diodes (RCLEDs) composed entirely of AlGaInP alloys are discussed. The devices consist of a strained quantum well optical cavity active region surrounded by AlInP/(AlGa)InP distributed Bragg reflectors (DBRs). The bottom DBR is a 60.5 period high reflector while the top partial reflector, which determines the emission linewidth, is a five-period output coupling DBR with a reflectance of about 57%. The devices exhibit linewidths of 4.8 nm (13.3 meV) at 300 K and are promising for plastic fiber communication systems and monochromatic displays. >

Wide angle laser radar device

Abstract: PURPOSE: To provide a wide angle laser device with optimum characteristics according to operation conditions, circumferential conditions, etc., and safety. CONSTITUTION: A time difference between the time when a reflection beam of pulse laser beam sent out from a light sending part 110 against a reflector is received at a light reception part 3 composed of a plurality of right reception elements 302 and the time until the reflection beam is received after it is sent out, and a distance from the position of the element 302 to the position of the reflector are measured by means of a distance/direction detection part 7. In this case, combination of reception elements 302 is controlled by reception element combination control means 9, 10 according to outputs of detection means 21 detecting conditions of a vehicle and conditions outside it, and outputs of the elements are added with adding means 11, then according to the addition output the distance and direction to the reflector is measured. COPYRIGHT: (C)1995,JPO

Unit of electric lamp and reflector

Abstract: The electric lamp-reflector unit has a molded reflector body (1) comprising adjusting ridges (22) integral with a reflector part (2) positioned at the light emission window (28).

Cellular phone antenna reflector

Abstract: The cellular phone antenna reflector of this invention has a tubular configuration. It is made up of three major components, an inner core, a shield and an outer component. The shield is made from a conductive material and encircles only a section of the inner core. The entire reflector of this invention is flexible and all of the components can be flexed for ease of use over an antenna.

Testing transmitter-receiver apparatus for sector cell base station

Abstract: In sector cell base stations, directive antennae with box-shaped reflectors are widely used. By way of a testing antenna incorporated such a reflector box, stable and appropriate electromagnetic coupling to the antenna elements of the directive antenna can be realized and undesirable coupling from outside the reflector box can be prevented, thereby improving the reliability of the testing system.

Quasi-optical power combining of solid state sources in K/sub a/-band

Abstract: Planar arrays of HEMTs (high electron mobility transistors) have been fabricated and tested at 37 GHz. The square arrays, consisting of 9 or 16 devices, have been mounted in a Fabry-Perot interferometer, which provides frequency locking. Measured power output and frequency spectra are presented and compared with analytical predictions. Output power is in the milliwatt range, and the line width of a typical array is about 50 kHz. The investigation has centered on using a semiconfocal Fabry-Perot resonator, with the array of sources placed on the planar reflector of the resonator. The curved reflector is partially reflecting to couple power out of the quasi-optical cavity. Source selection, quasi-optical cavity design and characteristics, and calculation of the circuit parameters for the oscillator interconnection grid are discussed. >