Showing papers on "Reflector (antenna) published in 1974"

Cassegrain antenna with improved subreflector for terrestrial communication systems

Abstract: A Cassegrain antenna for use in terrestrial communication systems. The antenna has the conventional subreflector including a central area which provides tapered illumination of the entire main reflector, and a peripheral area which directs spillover from the central area onto the peripheral portion of the main reflector to improve the uniformity of illumination of the main reflector, thereby improving illumination efficiency and reducing gain loss due to spillover. The central and peripheral areas of the subreflector are preferably both surfaces of revolution of conic sections of the same kind, such as hyperboloids, ellipsoids or paraboloids, although the peripheral area may be a frustoconical surface if desired. The virtual focal points of the two conic sections of the subreflector are both coincident with the phase center of the feed horn.

Arecibo heating experiments

Abstract: Enhancements of various features of the incoherent scatter spectrum are observed when the ionosphere is illuminated with powerful, high frequency radio waves. The radio waves excite plasma instabilities producing lines or more complex spectral features near the local plasma frequency, at the local ion acoustic frequency, near the local gyrofrequency, and near twice the gyrofrequency. The enhancements occur in a thin slab as observed by the incoherent scatter radar and at both upshifted and downshifted frequencies with respect to the probing radar frequency. The enhancements are observed to vary with time when the excitation is held constant and is turned on or off. The high power radio waves are produced by a 160 kw transmitter feeding a log-periodic pair of curtains mounted at the focus of the 1000-ft reflector and covering the frequency range from 5 to 12 MHz. The effects are observed with the incoherent scatter radar using the same reflector and with ionosondes and photometers. The frequencies of the enhanced plasma line and the ion line and their relation to the pump (high frequency radio wave) frequency are predictable from available parametric instability theory. Other spectral features are being explained as the theory develops with the help of the observations. There remain some discrepancies, in particular the asymmetries in intensity, width, and fluctuations of the upshifted compared to the downshifted plasma lines.

Solar energy conversion system

Abstract: A solar energy concentrator system which includes a centrally disposed column supporting a solar receiver means, and having an array of pivotally mounted support pads disposed circumferentially therearound. Each of the support pads retains a plurality of pivotally mounted solar reflective elements which are arranged to tilt about the axis of the pivotal mounting means and thereby direct reflected solar energy upon the solar receiver. The solar reflective elements are preferably generally planar, and are provided with means for tiltable as well as lateral adjustment so as to produce a Fresnel approximation of a large area reflector, and thereby increase the portion of solar energy reflected by the reflective elements onto the solar receiver.

Focused arc beam transducer-reflector

Abstract: An acoustic transducer-reflector using a single disc-shaped piezoceramic element radiating into a compound reflector for obtaining a line focus sound beam that is characteristic of focused-arc transducers that maybe used for underseas applications and for non-destructive materials testing. The single transducer emits acoustic energy into the compound reflector which reshapes a circular beam into a focused arc beam. A shadow mask or aperture stop positioned in front of the reflector assures a beam such as would be radiated from a ring source.

Reflection of clusters of helium, hydrogen, and nitrogen as function of the reflector temperature

Abstract: Clusters of helium, hydrogen, and nitrogen are reflected at a polished stainless steel plate at temperatures ranging from 80 to 550 K. The incident clusters contain on the average about 1.5×105 atoms of helium or molecules of hydrogen or 104 molecules of nitrogen, as measured by time‐of‐flight mass spectrometry. The angular distributions of the average sizes, the velocities, and the molecular intensities of the reflected cluster beams show that in the investigated range of reflector temperatures the reflection of the helium clusters corresponds to the hydrogen cluster reflection at higher reflector temperatures while the nitrogen cluster reflection corresponds to the hydrogen cluster reflection at lower reflector temperatures. The transition between the two regimes of reflection as observed with hydrogen clusters is marked by an optimum reflector temperature leading to a maximum intensity of the reflected beam, a minimum loss of clustered material, and a distinct angular separation of incident cluster sizes. At a grazing incidence angle of 84.3° the measured optimum reflector temperature for the hydrogen cluster reflection is 215 K and increases with decreasing angle of incidence. The two regimes of high‐temperature and low‐temperature reflection of clusters exhibit close phenomenological relationship to the regimes of thermal and structure dominated scattering of atoms from single crystal planes. In both cases the transition region is characterized by a maximum angle of reflection and a minimum divergence of the reflected beam. The features of high‐temperature cluster reflection are explained by a semiempirical model based on the evaporation recoil of the cluster molecules ablating after contact with the comparatively hot reflector surface.

In-line reflective lead-pair for light-emitting diodes

Abstract: A plurality of flat, subminiature, reflective in-line lead pairs for light-emitting diodes is contained in a frame. Each lead pair has a flat mounting surface for the diode chip. Although the diode chip is mounted on one of the lead pairs, the deep reflector for side-emitted light is formed from both leads of the pair. The reflector configuration provides for mounting semiconductor chips in addition to the diode chip therein. The reflector also precludes an illuminated light-emitting diode from inadvertently illuminating one or more adjacent light-emitting diodes.

Single polarizer reflective liquid crystal display

Abstract: A liquid crystal display is disclosed comprising a polarizer, a liquid crystal cell, a quarter wave plate and a reflector. In one embodiment, negative dielectric anisotropy liquid crystal materials are utilized in the cell. In another, positive dielectric anisotropy materials are utilized.

Optical measuring apparatus

Abstract: A measuring apparatus for measuring the density of smoke and the like comprising a light source for emitting a beam of radiant energy which is directed through the smoke which is to be measured, and a first reflector positioned in the path of said beam for redirecting said beam Chopping means are movable periodically into the path of the beam for interrupting the passage of the beam to the first reflector means A second reflector means on the chopping means is movable in the path of the beam when the beam is interrupted by said chopping means Means are provided for directing the light reflected by the first reflector means and the reflector means to a light sensitive means This invention relates to optical measuring apparatus and particularly to measuring apparatus for measuring the optical transmittance of smoke and the like

Low‐current‐density LED‐pumped Nd: YAG laser using a solid cylindrical reflector

Abstract: The dynamic behavior of Nd:YAG lasers is theoretically analyzed. In experiments, an array of twenty GaAlAs diodes was used as the pumping light source for a Nd:YAG laser. An index-matching glass half-cylinder was used instead of the conventional hollow metal reflector. The refractive index of the half-cylinder was 1.8, which matched the refractive index of the Nd:YAG rod. A maximum CW output power of 27 mW at a current density of 207 A/sq cm was achieved using this glass half-cylinder, while 6.7 mW were obtained when a hollow metal reflector was used.

Solar energy concentrating and collecting arrangement with sun-follower and solar energy sensing power control and method

Abstract: A solar energy concentrating and collecting arrangement and method in which a semi-cylindrical oblong concave reflector/concentrator forms the roof of a house, school or other building, particularly a heat utilization building. A collector is movably supported in spaced relation above and along the length of the oblong roof/reflector concentrator, for pivotal movement, by a solar reflection energy sensing and seeking drive control arrangement, to a zone of maximum confluence of solar energy rays reflected from the roof/reflector concentrator as a result of variations of sun path during the various parts of the year and also to further accommodate each day's movement of the sun. Movement of the collector is by pivotal movement about an axis parallel with the center of curvature or curvatures of the roof/reflector concentrator and disposed adjacent the roof/reflector concentrator. The roof/reflector has a plurality of radii, for enabling accommodation of wide variations of the sun angles during the various seasons of the year and during each day of a given season, while still affording a desired concentration of solar energy on the collector. The concentrated solar energy collected by the collector is transferred to a fluid, such as water, passed along the length of collector, by a pump forming a part of a heat utilization system, which may include heating and/or cooling of the building and/or additional buildings or other structures. The roof/reflector concentrator is oriented with its center of curvature axes running East-West and with its surface tilted toward the Equator, the degree of tilt being dependent upon the latitude of the reflector.

Wide-angle on-axis projection system

Abstract: The invention provides a wide-angle common axis projection system wherein a reflector and a see-through beam splitter reflector are combined with a projector means having a wide angle lens and a display screen of spherical shape to develop on-axis image projection for wide-angle display in relation to a viewer''s point located on the non-reflective side of the beam splitter reflector.

Compact frequency reuse antenna

Abstract: A compact antenna system that permits orthogonally polarized frequency reuse operation is achieved by two overlapping parabolic reflectors. Each of the reflectors has a reflecting surface comprised of parallel, reflecting, conductive elements with the reflecting elements of one reflector polarized orthogonally to the reflecting elements in the other. Each reflector has an associated feed copolarized with the reflecting elements of the particular reflector. The two reflectors are overlaid without coinciding their respective focus points so that cross-polarized fields generated by the parallel elements in the surface of each reflector from its associated feed are scattered away from the copolarized beam of each reflector.

Directive disk feed system

Abstract: A multiple beam antenna having either a main reflector or a lens is illuminated by a feed system comprising a number of primary radiators such as dipole elements. Primary radiation from each dipole element reflects from the principal reflector to produce a different respective one of the multiple secondary beams in the remote field. A disk-shaped electrically conductive director is located in the primary radiation path near each primary radiator. Each director operates both to shape the primary pattern of its respective primary radiator directly, and also to excite parasitic radiation in neighboring primary radiators so as to produce a primary radiation pattern whose shape approximates a sector of a circle, thereby producing high illumination efficiency at the main reflector. The desired sector shape of primary pattern is achieved despite relatively close lateral spacing between adjacent primary radiators of the feed system. The close spacing enables achievement of high beam crossover level between adjacent secondary beams in the remote field.

Lamp with tubular bulb and reflector

Abstract: Disclosed is an electric lamp comprising a reflector and a tubular-shaped bulb having an illuminating arc of a length which is short in comparison to the total length of the bulb. The reflector encloses essentially only the arc portion of the bulb, thereby enhancing the performance and design of the lamp. A novel rear reflector design is also provided for maximizing the efficiency of the lamp.

Photoflash lamp array having electrically connected reflector

Abstract: A photoflash lamp array comprising a plurality of flash lamps having lead-in wires connected to a circuit board carrying switching circuitry for sequentially firing the flash lamps. An electrically conductive reflector unit is positioned between the lamps and the circuit board. A conductive clip is clipped to the reflector unit and touches against an electrical ground point on the circuit board, whereby the reflector unit functions as an electrical shield for the circuitry.

Thermonuclear micro-explosions with intense ion beams

Abstract: HIGH density pellet compression may be important in laser fusion1. In this way the minimum energy input for breakeven can be substantially reduced to levels within reach of expected future laser technology. Further2 when this concept is applied to a fissionable pellet surrounded by a small neutron reflector, preferably TD, which is compressed together with the reflector, to high densities, very small critical masses become possible; in addition the fission process could ignite a thermonuclear reaction in the TD reflector. In these proposals very large laser energies of ∼ 1 MJ, which may be difficult to reach, are required. As an alternative to laser fusion I have proposed the use of intense relativistic electron beams3, but here the beam pulse length is longer than for laser beams, and the electron stopping range may be too long.

Analysis of rotationally symmetric reflectors for illuminating systems

Abstract: The design of an illuminating system consisting of a reflector with a small source, which illuminates its aperture with a preassigned continuous distribution everywhere greater than the direct illuminance distribution, is, mathematically, a singular boundary-value problem. If the rays of light striking an area en the edge of the reflector next to the aperture are to be reflected to an adjacent area on the aperture, then there exist no, one, or two solutions to the problem, depending on the size of the aperture and the reflectance of the surface. If the rays striking an area on the aperture edge of the reflector are to be reflected to the diametrically opposite edge of the aperture, then we obtain a unique solution. We derive the results only for rotationally symmetric systems.

Collinear dipole array with reflector

Abstract: This invention comprises an antenna array of collinear, end-fed dipoles spaced substantially less than one-quarter wavelength from the reflector. Consecutive dipoles are energized through phasing loops with the end dipole energized by a coaxial feeder or by one of the two output ports of a balun. A radome with a helically wound resistance heating wire is used to protect the array from the elements. Means comprising the addition of small auxiliary radiators at one of the ends of each dipoles are provided to reduce radiation polarized perpendicular to the axis of the array.

Flashing reflector system

Abstract: A flashing reflector system in which at least one retroreflective reflector having at least one wide angle area thereon is mounted on one side of a revolvable wheel member. When this assembly is revolved, a characteristic, highly visible flashing of retro-reflected light is produced which is visible over wide side angles relative to the revolving wheel member.

360{20 {0 Azimuth scanning antenna without rotating RF joints

Abstract: A 360* scanning radar antenna has a plurality of primary focusing-structures arranged in a circular fashion illuminating corresponding secondary focusing-structures which in turn are arranged about, and directed toward, a rotating multi-sided halfwave plane reflector. Radar energy is switched to radiate from a given primary focusing-structure during the time when the plane reflector is in position to reflect all of the energy collimated by the corresponding secondary focusing-structure. The secondary focusing-structure may be made to appear transparent to the beam reflected by the plane reflector.

Developments in optically focusing reflectors for small-angle X-ray scattering cameras

Abstract: The quality of the reflecting surface and the mechanical perfection of the bending mechanism are factors which affect the performance of curved glass reflectors in optically focusing small-angle X-ray scattering cameras. The intensity of the reflected beam can be enhanced by gold-coating the reflector, both because of the higher reflectivity of gold and because larger grazing incidence angles are possible, thus increasing the optical aperture. Coating imperfections and the use of increased incidence angles are factors which increase the parasitic scattering. A new bending mechanism is described in which two 200 mm long reflectors are arranged in series to form a reflector of effective length of nearly 400 mm.

Antenna array for aircraft guidance system

Abstract: The antenna array preferably consists of a plurality of slotted wave guide microwave signal radiating elements positioned to directly radiate separate beams of microwave energy at different azimuth angles to a common horizontally aligned cylinder sector reflector, the radiating elements being operable to primarily determine the direction and shape of the resultant reflected beams in azimuth and the reflector being operable to primarily determine the elevation patterns of the resultant reflected beams.

The upgraded arecibo observatory.

Abstract: Arecibo Observatory9s giant spherical reflector antenna has undergone a massive upgrading over the past 3 years. The surface of the reflector has been replaced with aluminum panels to obtain an accuracy of 3.2 mm r.m.s. over the reflector surface. The superstructure has been stabilized and modified to permit operation at S-band frequencies. A high-power S-band radar transmitter has been added to the existing UHF system. These additions and improvements provide the observatory with new and promising research capabilities in the fields of radio and radar astronomy.

Variable beamwidth antenna

Abstract: An antenna system for single or plural beams providing continuously variable beamwidth selectively in one or both of two orthogonal senses, i.e., azimuth and elevation, for either communications or angle-tracking. The system includes two parabolic cylindrical reflectors, which are respectively a main reflector and a sub-reflector; the reflectors are positioned with the focal axes thereof orthogonally. A point or multibeam (e.g., monopulse) feed is mounted adjacent the main reflector on the focal axis of the sub-reflector in the Airy disc of the system. Beamwidth is controlled using telescoping sections on the main and sub-reflectors to control the size of the surface areas thereof. Simultaneous operation of the telescoping sections of the reflector and sub-reflector provides bidirectional zooming of the beam without distortion while individual operation of the sections of the reflectors permits unidirectional zooming. Bidirectional zooming of beams from the multibeam feed requires rotating the position of the multibeam feed as the Airy disc changes during adjustment of the telescoping sections.

Pavement marker having conical retro-reflectors

Abstract: A pavement marker including a housing having a base for engagement with the surface of a roadway and a reflective wall for reflecting light from vehicles on the roadway when the fore-and-aft axis of the housing is disposed in parallel relationship with the direction of travel of vehicles on the roadway. The central portion of the reflective wall is formed with a plurality of conical reflector elements having relatively high optical efficiency for reflecting incident light rays on the outer surface of the reflective wall that are substantially in a horizontal plane parallel to the plane of the base and that are substantially parallel to the fore-and-aft axis of the housing, but having relatively low optical efficiency for reflecting light rays making a substantial acute angle with respect to the plane of the base or the fore-and-aft axis of the housing. Wide angle reflector elements are formed on side portions of the reflective wall projecting from opposite ends of the central portion. The wide angle reflector elements are of a configuration other than conical and have less optical efficiency than the conical reflector elements for reflecting incident light rays on the outer surface of the reflective wall that are substantially in a horizontal plane parallel to the plane of the base and that are substantially parallel to the fore-and-aft axis, but have greater optical efficiency than the conical reflector elements for reflecting incident light rays that make a substantial acute angle with the plane of the base or the fore-and-aft axis of the housing. The conical reflector elements each have an apex located remotely from the outer face of the reflective wall and an axis passing through the apex and lying in a plane that is perpendicular to the plane of the base and parallel to the fore-and-aft axis of the housing, the axis of each of the conical reflector elements extending at an acute angle with respect to the normal to the outer face such that the conical reflector elements are oriented to receive incident light refracted from the outer face and reflect the light in a direction substantially parallel to the direction of incidence. The wide angle reflector elements are of the cube corner type in the preferred embodiment. In a modified embodiment, the wide angle reflector elements are of spherical configuration, the spherical reflector elements providing good wide angle performance but having lower optical efficiency than the cube corner reflector elements.

High output low brightness ventilated luminaire

Abstract: A multi-purpose, high output, low brightness luminaire employing a large open front box-like housing with opposed lamp sockets in the side walls adapted to accommodate high wattage, high intensity discharge (HID) lamps is disclosed. Upper and lower curved reflectors are mounted adjacent the back wall of the housing and an oppositely curved intermediate, perforated reflector overlies a space between the upper and lower reflectors. The perforated reflector directs air entering through the back wall both through the perforations to sweep the lamps as well as upwardly and downwardly over the upper and lower curved reflectors. A perforated reflector screen is also provided across the luminaire in front of the lamps to shield the lamp arcs from view and if desired, a plurality of vertically and horizontally oriented louvers are provided to selectively control light distribution.

Plastics articles heated by infra-red radiators and reflectors - along two parallel paths with radiators between

Abstract: The parent patent describes a device for heating plastics articles, esp. for further treatment, which consists of an infra-red radiator and a curved reflecting surface. In the patent of addn., the infra-red radiators are mounted between two conveying paths for work-pieces, and reflecting surfaces are arranged symmetrically about the central plane of the radiators, thus reflecting the heat back onto the workpieces. In the parent patent, one side of each workpiece received radiation from a reflector only, while the other side received it both from a reflector and from the heat source, resulting in some inbalance. In the new arrangement, this is largely corrected.

Dual frequency feed horn using notched fins for phase and amplitude control

Abstract: A dual frequency band horn-type antenna feed is described which has primary application to optimally illuminate a parabolic cylindrical reflector operating simultaneously at high power in both of the two bands. The principle of the invention is applicable to any two frequency bands regardless of their frequency separation including coincidence as a limiting case. The basic requirement of such a feed is that it must be as directive as possible within constraint of the feed aperture size in the plane of the cylinder axis because the cylindrical reflector does not collimate the beam in this plane and it must be relatively nondirective in the plane of the parabola for efficient illumination of the reflector. This requirement requires the phase front in the directive plane to be controlled within a small fraction of a wavelength at both frequencies.

Antenna system for primary and secondary radar

Abstract: A common antenna system for a primary and a secondary radar transceiver is described. The primary feeder connected to the primary transceiver is provided with two probes for transmitting and receiving through it the interrogation signals of the secondary transceiver. Two ancillary feeders are mounted on either side of the primary structure to transmit and receive a side lobe suppression signal for the secondary transceiver. The feed system is located at the focus of a reflector common to both primary and secondary transceivers.

Integrated radiometric seeker gyro

Abstract: A radiometer and gyroscope are integrated in a single unit by coupling part of an antenna directly to the spinning inertial mass or rotor of the gyroscope. In the preferred embodiment a Cassegrain antenna is coupled to a dynamically tuned, wide-angle, free-rotor gyro by connecting the smaller secondary reflector to the gimbal-mounted rotor. A stationary antenna feed and waveguide are arranged inside of the hollow drive shaft. While the rotor, primary and secondary reflectors are spinning, the rotor and secondary reflector attached thereto can be tilted off the spin axis, to which the primary reflector, however, is constrained.