Showing papers on "Reflector (antenna) published in 1983"

Reflective solar tracking system

Abstract: A reflective solar tracking system of the type arranged to reflect light rays from the sun onto a remote solar energy collector is described. The system comprises a reflector mounted on an assembly incorporating a drive mechanism for rotating the reflector about two axes to compensate for altitudinal and azimuthal changes in the position of the sun. A sensor device is adapted to point at the sun and provide control signals to the drive mechanism so that the reflector is moved in response to solar movement such that sunlight is always reflected onto the collector and at the same time the sensor device is moved so as to track the sun.

Variable magnification stage light

Abstract: A variable magnification "zoom" spotlight assembly is disclosed in which the diameter and focal length of the focusing lens and object lens are selected so that the angle of incidence of a light ray as it emanates from the lamp and reflector of the assembly and thereafter from the focusing and objective lenses decreases by a constant factor. This angular relationship is established by selecting the diameter and focal length of the focusing lens and objective lens and the diameter and length of the reflector according to the following angular relationship: B.sub.R /B.sub.F ≅B.sub.1 /B.sub.R ≅B.sub.2 /B.sub.1 =k Where: B F =angle of the filament to reflector as measured from the focal axis; B R =angle of gate to reflector as measured from the focal axis; B 1 =angle of focusing lens as measured from its focal length along the focal axis to its radius; B 2 =angle of objective lens as measured from its focal length along the focal axis to its radius; and, k=constant.

Low side lobe gregorian antenna

Abstract: A microwave antenna comprising the combination of a paraboloidal main reflector; a subreflector located such that the paraboloidal main reflector and the subreflector have a common focal point lying between the main reflector and the subreflector; a feed horn for transmitting microwave radiation (preferably symmetrically) to, and receiving microwave radiation from, said subreflector; and a shield connected to the peripheral portion of the subreflector and having an absorbing surface which reduces side lobe levels both by capturing the feed horn spillover energy and by reducing the diffraction of microwave radiation from the edge of the subreflector. The shield is preferably formed as a continuous axial projection extending from the periphery of the subreflector toward the main reflector substantially parallel to the axis of the feed horn. The reflective surface of the subreflector is suitably a section of an approximate ellipse.

Solar tracking unit

Abstract: A solar tracking system having particular utility for insuring that a relatively lightweight solar collector is properly positioned with respect to the sun. A parabolic reflector surface is included to provide a line of focus of the sunlight directed toward a cylindrical energy absorption tube. Photovoltaic cells provided on either side of the energy absorption tube are directed toward the parabolic reflector surface. A reversible motor is electrically connected to the cells and physically connected to the reflector system for correcting any misalignment with respect to the sun. The reversible motor can be used as the sole means for powering the tracking system or can be used in conjunction with an outside power source.

Electronic flash with flashtube retention strap

Abstract: An electronic flashtube is fixedly mounted to a reflector housing by an elongated elastomeric strap having openings therethrough at opposite ends thereof for engaging respectively the opposite end portions of the flashtube which extend from the reflector housing. The elongated strap extends across the exterior of the reflector housing so as to yieldably bias the flashtube toward that portion of the reflector housing across which the strap extends.

Surface acoustic wave resonator

Abstract: PURPOSE:To decrease the capacitance ratio and to increase the Q at anti- resonance point by selecting the number of teeth and the film thickness of an interdigital grating reflector so that the resonance frequency is arranged to a stop band lower limit frequency of the reflecting characteristic of the grating reflector and the anti-resonance frequency is arranged to the upper limit frequency. CONSTITUTION:The structure of the resonator is of one terminal pair type, an LiTaO3 36 deg. rotating Y board of a piezoelectric substrate 1 is used, an interdigital electrode 2 (20 pairs) made of an aluminum thin film of 0.1mum thickness is provided, and then the grating reflectors 3, 4 where 200 each stops of 1.0mum of line width being 1/4 of the surface acoustic wavelength are arranged at an interval of 1/2 wavelength at both sides are provided. Since the number of the teeth of the interdigital electrode 2 and the grating reflectors 3, 4 and the aluminum film thickness are selected so that the resonance frequency fr is arranged at the left shoulder and the anti-resonance frequency fa is arranged at the right shoulder, although the loss at the resonance frequency is decreased slightly, the width of the anti-resonance Q and the width of the resonance versus anti-resonance frequency is improved.

Holographic laser protection device

Abstract: A holographic reflector (20) for reflecting laser radiation at a predetermined wavelength. The reflector employs a plurality of holograms (31, 33) which are disposed adjacent to one another and which are conterminous with each other. The holograms (31, 33) are generally disposed in a support structure (21) which may be a visor or goggle arrangement. Each of the holograms may be either parallel fringe holograms or slanted fringe holograms. The angular orientation of the fringes and the relative spacing thereof determine the angular coverage provided by the reflector (20). The reflector (20) provides for reflection of laser radiation at a predetermined wavelength and within a particular angular subtence (DELTA)3,DELTA)4,DELTA)5) while allowing high see-through in the visible wavelength region. Multiple sets of holograms may also be stacked in order to protect against multiple laser sources.

Ultrasonic process for measuring stress in a bolt or similar part adapted to this method

Abstract: The method for measuring strains in a part uses the reflection of an acoustic wave, while measuring a transit time of said wave by means of an apparatus which measures the fade-in time of an echo coming from an interface. The method comprises the steps of selecting within the medium one or a plurality of ends of rectilinear measuring runs, which ends are embodied by an inner artificial reflector (8, 9) emitting of a beam of acoustic waves so that acoustic rays carrying sufficient energy strike the useful reflectors, selecting the echoes corresponding to the reflectors, determining by measurement the transit times which are characteristic of the useful acoustic rays up to the inner artificial reflectors and transposing the transit times for each inner reflector considered individually or the respective differences of transit times for each couple of reflectors into an outer strain value or into a strain value within the region delimited by each couple of reflectors. The part for implementing such method comprises reflectors consisting particularly of perforations or bores into the part.

Non-contacting distance measuring system

Abstract: To determine if a pulsed beam system, typically an ultrasonic pulsed beam system, which is located externally of a motor vehicle is in operative condition, a transmitter (14) projects a beam to a fixed reflector (16) located on the vehicle, and one (19) of a group of timing stages (18; 19, 20, 21) evaluates the transit time to the reflector. If the transit time to the reflector is slightly less than a predetermined time interval (Tc), so that the threshold timing level (Tc) is passed, a first indication, for example a frequency at a first tone (f1), generated by an acoustic tone generator (30) is reproduced in a loudspeaker; if, then, an obstruction is sensed by the beam, and the distance between the transmitter (14) and the obstruction (17) which forms a reflecting object drops below a first predetermined distance represented by a time period (T2), a second one of the transit time stages responds, and, through logic gates (22-24, 28, 29) provides a second discrete output frequency (f2) in the loudspeaker. If the vehicle closely approaches the reflecting object or obstruction (17), a third frequency (f3) is reproduced by the loudspeaker (26) and, additionally, a warning signal can be given. The system can be connected to the reverse gear or rear light switch, so that, if no obstruction is sensed, and only the signal from the reflector is reproduced, an audible indication of "reverse gear engaged" is provided, thus simultaneously providing a reverse gear signal as well as a signal representative of proper operation of the system. To compensate for ambient condition, dirt on the transmitters, and the like, the timing intervals by the transit time stages responding to the obstruction can be changed (FIG. 2) by providing a calibrating input based on actual transit time from the transmitter (14) to the fixed reflector (16).

Temperature compensating semiconductor lasers

Abstract: A semiconductor laser is constructed such that at least a part of the laser optical feedback is provided by an external reflector spaced from the semiconductive material of the laser so as to form a composite optical cavity bounded by the semiconductive material and the reflector. The external reflector is supported on a mount constructed such that in response to changes in temperature the mount moves the external reflector relative to the adjacent surface of the semiconductive material so as to provide the external part of the optical cavity with a thermal coefficient substantially matched with the mode wavelength expansion coefficient of the internal part of the cavity. In another embodiment the external reflector is supported on a mount constructed such that in response to changes in temperature it moves the external reflector relative to the adjacent surface of the semiconductor material so as to provide the external part of the optical cavity with a thermal expansion coefficient substantially matched with the peak gain wavelength expansion coefficient. In other embodiments, the external reflector is supported on a mount constructed such that in response to temperature changes it moves the reflector relative to the anti-reflection coated adjacent surface of the semiconductor material so as to provide the external part of the cavity with a thermal expansion coefficient such that the composite cavity has a mode wavelength expansion coefficient substantially equal to zero or the composite cavity has a mode wavelength expansion coefficient substantially equal to the peak gain wavelength coefficient.

Method and apparatus for controlling lasers

Abstract: A method and apparatus for controlling an external cavity of a semiconductor laser to maintain its emission in a single longitudinal mode. The length of the external cavity is varied by an electromagnet acting on ferromagnetic material attached to a copper foil reflector. Total optical power output of the laser is monitored and single longitudinal mode operation is achieved by maximizing the power output. An active technique employs modulation of the reflector position about a mean value. The magnetic manipulation of the reflector may find application in other laser systems, e.g. gas lasers.

Double reflector antenna with integral radome reflector support

Abstract: A two reflector microwave antenna has a concave focusing main dish having an integral peripheral flange An integral radome shell also having a peripheral flange is disposed in confronting relationship to the main dish flange Mounted over both flanges is a clamping ring to keep the main dish and radome shell in a stress condition of fixed edge shells A secondary reflector is provided on a central portion of the radome The concave focusing main dish in one example, defines a paraboloid of revolution Specific shapes of the main dish and the radome shell are selected to appropriately focus the microwave radiation A radome portion of a variable thickness of dielectric material of the integral radome shell modify the path of microwave energy compensating for diffraction of induced edge spillover The stress condition of the shells as maintained by the clamp about the flanges provides a structually rigid antenna substantially void of structural elements

Gold-plated tungsten knit RF reflective surface

Abstract: An improved antenna mesh material is made of gold-plated tungsten wire. Because gold-plated tungsten can be drawn to a very fine diameter (less than one mil) it results in a knit mesh having low mechanical stiffness. It also has high electrical conductivity, thereby enhancing its operation as an antenna reflector up to the higher RF frequencies (EHF). In addition, gold-plated tungsten has both sufficient tensile strength and a low coefficient of thermal expansion which enables it to maintain high reflector surface accuracy for changing thermal conditions.

Survey of deployable antenna concepts

Abstract: Deployable space antenna concepts are surveyed. Precision reflector antennas, stiffened membrane antennas, truss antennas, infrared antennas, and electrostatically figured membrane reflectors are described.

Extended life incandescent lamp with self contained diode and reflector

Abstract: An incandescent lamp having an extended operating life with a high operating efficiency in terms of lumens per watt. The lamp incorporates a rectifying diode (40) in series with the filament (26) and the filament (26) has an operating temperature less than 2550oC. A reflector (28) is mounted in the neck portion (14) of the lamp for reflecting visible light outwardly through the bulb portion (12) of the envelope (10) and for minimizing convection currents in the base (32) of the lamp. The diode (40) is disposed between the reflector (28) and the lamp base (32).

Apparatus for automatically directing solar radiation focused by a reflector

Abstract: For the tracking control of a reflector focusing the solar radiation on an absorber corresponding to the apparent movement of the sun, an adjusting mechanism of the reflector is driven by means of a direct-current motor 5. The terminals of the electric motor are connected to a parallel connection consisting of two solar cells (9, 10). The parallel connection of both solar cells is such that they generate by constant radiation about a similar amount of voltage however with opposite polarity. The driving of the direct current motor takes place with the voltage differential occurring on the parallel connection. Both the solar cells are rigidly mounted to that part of the stationary arranged absorber on which part the solarrays are focused by the reflector. Both the solar cells are arranged symmetrical to the longitudinal axis of the absorber. With the help of the above described apparatus the reflector is automatically always so adjusted that the solarrays are focused on the absorber whereby no additional source of energy is necessary to drive the adjusting mechanism of the reflector.

Image transmission through a turbulent medium using a point reflector and four-wave mixing in BSO crystal.

Abstract: A method of one-way image transmission through a turbulent medium is presented using four-wave mixing in BSO crystal. In this method, a pointlike reflector is placed on the observation plane to return part of the incident wave, giving the instantaneous wave propagation function of the turbulent medium to the image transmission side. The returned wave together with the plane reference wave and the Fourier-transformed input image wave is impinged in BSO crystal to modulate the image wave by the phase-conjugate wave, so that transmission of the image with reduced turbulence effects is achieved. The principle and laboratory experimental results are given.

First-order correction of aberrations in Cassegrainian and Gregorian antennas

Abstract: Cassegrainian and Gregorian reflector arrangements are needed for multibeam ground station and satellite antennas. In these antennas one or more feeds are displaced from the focus. This displacement normally causes aberrations, due primarily to astigmatism and coma. In a previous article, astigmatism was eliminated for small feed displacements by centering the antenna aperture with respect to the equivalent paraboloid axis. In this article coma is also removed by deforming the reflectors without causing spherical aberration, and simple expressions for the deformation coefficients are derived. The analysis applies in general to an arrangement of N reflectors. The deformations required to correct astigmatism, if the antenna aperture is not centered is also derived.

Device for simulating combat firing between combat participants

Abstract: A device is disclosed for combat simulation, in which each weapon carryingombat participant has a laser transmitter, an optical measurement receiver, and an analyzer, and each target object combat participant has reflector elements, an optical information receiver and a device for evaluating the optical information. When firing is simulated, the target is tracked with laser pulses which are transmitted by the laser transmitter and reflected by the reflector elements back to the measurement receiver. The hit accuracy information is optically coded and sent back to the target. According to this invention, optical signals or beams for target tracking and for information transmission are spatially separated from each other by distributing the reflector elements in the vulnerable area of the target, but locating the optical information receiver separately, preferably in an exposed location. The reflector elements may be inexpensive disposable elements. Signal transmission between the various components can be accomplished by optoelectronic links without the use of cables. On receipt of a "hit" signal, an optoelectronic link which activates the laser transmitter can be unavoidably switched off to inactivate the combat participant that has been hit without any possibility of tampering by the combat participant to prevent this.

Automatic tracking system with infrared and ultraviolet detection

Abstract: An automatic tracking system for tracking the sun on a path across the sky, comprising a reflector, a pre-programmed, automatic timed drive mechanism connected to the reflector for driving it on a given path, both ultraviolet and infrared sensors positioned on the reflector, means for comparing the amount of light detected by opposing sensors, and means for tilting the reflector about a horizontal and a vertical axis until the amount of light detected by each pair of sensors is equalized.

Unique reflector arrangement with very wide field of view for multibeam antennas

Abstract: We minimise the aberrations arising in a double reflector antenna when the feed is displaced from the focus. In a previous article, astigmatism and primary coma were reduced by slightly deforming the two reflecting surfaces and optimising the principal ray angles of incidence. Here we further reduce aberrations by determining the optimum subreflector magnification. The result is a new reflector arrangement, consisting of a deformed paraboloid combined with a deformed hyperboloid, having the widest possible field of view obtainable with two reflectors in a compact arrangement of short focal length.

Parasitic array with driven sleeve element

Abstract: To provide broad bandwidth in a multiple-band directional antenna, the antenna includes an array of parallel horizontal elements, which are: (1) an open-sleeve dipole as the driven element; (2) a trap director element; and (3) trap reflector elements. The driven element includes: (1) a trap central dipole which is center-fed and has sections self-resonant within the bands of 21.0 to 21.45 megahertz and 14.0 to 14.35 megahertz; and (2) two unequal-length sleeves self-resonant at 28.0 to 29.7 megahertz. The director and reflector elements are resonant in the same bands and are spaced and tuned for directivity of the array.

Electromagnetic radiation reflector structure

Abstract: A deployable spacecraft borne circular reflector structure comprises a plurality of plies of graphite fiber reinforced epoxy (GFRE) fibers, each ply comprising at least two layers of graphite epoxy reinforced fibers having quasi-isotropic properties. A circular ring of multiple layer plies of like construction as the reflector and having a U-shaped cross-section is bonded to the reflector rear surface adjacent the reflector peripheral edge. Each layer of each structure is formed from prepreg graphite fiber epoxy reinforced material.

Design concepts for large reflector antenna structures

Abstract: Practical approaches for establishing large, precise antenna reflectors in space are described. Reflector surfaces consisting of either solid panels or knitted mesh are considered. The approach using a deep articulated truss structure to support a mesh reflector is selected for detailed investigations. A new sequential deployment concept for the tetrahedral truss is explained. Good joint design is discussed, and examples are described both analytically and by means of demonstration models. The influence of curvature on the design and its vibration characteristics are investigated.

Synchronously-pumped phase-conjugate laser

Abstract: Laser apparatus which employs the principles of phase conjugation to provide for short-pulse operation. A phase-conjugate reflector (21), lasing medium (22), and output coupling device (23) are arranged to form a laser resonator. The lasing medium may be pumped by a conventional pump source (25) to produce population inversion in the lasing medium. The phase-conjugate reflector is pulsed by means of a pulsed pump source (24) which applies a periodic train of short laser pulses having high peak power and low average power thereto. The short-duration pulses create high reflective efficiencies in the phase-conjugate reflector, while minimizing the overall energy demands on the system. Additionally, the pump source which pumps the lasing medium may also provide pulsed energy thereto which is synchronous with the pulsed energy provided by the pulsed pump source to the phase-conjugate reflector. Accordingly, the system provides for a series of short pulsewidth laser pulses at its ouput.

High intensity security flashlight with duffusing parabolic reflector

Abstract: Although small enough to fit in a purse, this flashlight operates on six volts using a full-size flashlight bulb and casts a bright and quite-uniform beam of light, primarily for brief uses at relatively short range. The uniformity of the beam is obtained by a novel optical system, that includes an unsilvered, preferably generally parabolic reflector and a beam-narrowing lens. The combination of compactness and brightness is obtained by novel arrangement of the bulb and four penlight cells within the battery case, enhanced by the geometry of the reflector and lens.

Array antenna system with low coupling elements

Abstract: A scannable antenna array especially suited for aircraft having a common reflector and a plurality of spaced apart end-fired Yagi type elements each comprising a driver and one or more director segments spaced mutually from each other and the driver in the direction of the field pattern for the array. In the preferred embodiment, the driver is a dipole comprised of two laterally extending hooked-back radiating segments so dimensioned and spaced from the director elements so as to minimize the mutual electromagnetic coupling among elements of the array. In other embodiments, the driver may comprise a slot.

Thermal energy transfer device

Abstract: A thermal energy device is disclosed and generally includes one or more collector means for receiving and storing thermal energy, movable thermal reflector means, fixed thermal reflector means, and actuation apparatus for rotating the movable thermal reflector means about said collector means. The movable thermal reflector means preferably include thermal insulation means for preventing undesirable heat gain or loss and are rotated between a first position wherein the reflector means are positioned between the collector means and the interior of a building structure and function to reflect and concentrate exterior ambient thermal energy on to the collectors for storage therein. The movable thermal reflector means is also rotatable to a second position generally between the collector means and the exterior of the building structure in order to reflect and disperse previously-stored thermal energy from said collector means into the interior of a building structure. Such positions and rotations may be reversed during warm weather to collect thermal energy from the interior of the building and discharge such energy to the exterior surroundings. Furthermore, the reflectors may be rotated to positions intermediate said first and second positions, if desired, to maximize light transmission when heating and cooling are not necessary. The energy transfer device may also optionally include various devices and apparatus for automatically rotating the movable thermal reflector means in response to predetermined conditions, for providing convective heat transfer and dispersal, as well as various other optional features.

Initial '80s Development of Inflated Antennas

Abstract: State of the art technology was considered in the definition and documentation of a membrane surface suitable for use in a space reflector system for long durations in orbit. Requirements for a metal foil-plastic laminate structural element were determined and a laboratory model of a rigidized element to test for strength characteristics was constructed. Characteristics of antennas ranging from 10 meters to 1000 meters were determined. The basic antenna configuration studied consists of (1) a thin film reflector, (2) a thin film cone, (3) a self-rigidizing structural torus at the interface of the cone and reflector; and (4) an inflation system. The reflector is metallized and, when inflated, has a parabolic shape. The cone not only completes the enclosure of the inflatant, but also holds the antenna feed at its apex. The torus keeps the inflated cone-reflector from collapsing inward. Laser test equipment determined the accuracy of the inflated paraboloids.

Light modulation sensor in a vortex shedding flowmeter

Abstract: A sensor which provides an output signal representative of a parameter such as pressure, includes a reflector, a lens and a waveguide which are relatively movable as a function of the parameter. Light from a light source is transmitted by the waveguide toward the reflector. The lens, which is positioned between the waveguide and the reflector directs the light from the waveguide to the reflector and focuses the reflected light proximate a receiving surface of the waveguide. A sensor housing supports the waveguide, lens and reflector so that a relative physical displacement between the waveguide, lens and reflector occurs which is responsive to the parameter. The light received by the waveguide at its receiving surface is a function of the relative physical displacement, and thus a function of the parameter. The waveguide transmits the received light to a light detector which produces an electrical output signal which is a function of the received light and therefore of the parameter.