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Topic: Parabolic reflector


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In the News (Sun 18 Aug 19)

  
  Parabolic antenna - Wikipedia, the free encyclopedia
The Parabolic antenna is a high-gain, reflector antenna used for radio, television and data communications, and also for radiolocation (RADAR), on the UHF and SHF frequencies.
A typical parabolic antenna consists of a parabolic reflector illuminated by a small feed antenna.
The reflector is a metallic surface formed into a paraboloid of revolution and (usually) truncated in a circular rim that forms the diameter of the antenna.
en.wikipedia.org /wiki/Parabolic_antenna   (462 words)

  
 Parabolic reflector - Wikipedia, the free encyclopedia
A parabolic reflector (also known as a parabolic dish or a parabolic mirror) is a reflective device formed in the shape of a paraboloid of revolution.
The parabolic reflector functions due to the geometric properties of the paraboloid shape: if the angle of incidence to the inner surface of the collector equals the angle of reflection, then any incoming ray that is parallel to the axis of the dish will be reflected to a central point, or "focus".
The most common applications of the parabolic reflector are in satellite dishes, telescopes (including radio telescopes), parabolic microphones, and many lighting devices such as spotlights, car headlights, and LED housings.
en.wikipedia.org /wiki/Parabolic_reflector   (328 words)

  
 Encyclopedia: Parabolic reflector   (Site not responding. Last check: 2007-11-06)
The exemplary concentrators geometrically comprise a predetermined portion of a parabolic mirror in combination with a planar mirror that allows light to be focused on and along a predetermined portion of the surface of the parabolic mirror, or alternately along a predetermined portion of the surface of the planar mirror.
The second parabolic reflector 72 allows the corner 74 to be removed thereby decreasing the overall height of the double reflecting parabolic concentrator 70.
Ideally, the second parabolic reflector 72 is positioned such that it does not interfere with the reflection of incident light 40 as it reflects from the primary surface 52 to the secondary surface 54.
www.nationmaster.com /encyclopedia/Parabolic-reflector   (1299 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
Where the parabolic reflector assembly 10 is to be used externally as in solar energy collecting apparatus, the parabolic base member 11 may be formed of galvanised sheet metal to reduce corrosion.
4 and 5, the parabolic reflector assembly 10 may be used in solar energy collecting apparatus as a parabolic concentrator with the formed parabolic reflective surface 20 concentrating energy on a suitable target for example a tubular member carrying an energy transfer medium which is arranged at the focus of the parabolic reflector assembly.
A parabolic reflector assembly as claimed in Claim 1 or Claim 2 wherein said reflective material is in the form of or is carried by a flexible sheet.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/98800.011227&ELEMENT_SET=DECL   (2564 words)

  
 Clip fasteners for parabolic dish reflector panels - Patent 4743095
A parabolic reflector having support structure, preferably mounted on wheels for rotation, for supporting a dish framework to which is mounted a multiplicity of adjacently placed reflector members for focusing solar rays on a linear collector.
Parabolic reflector 10 includes support structure 20 carrying a parabolic dish framework 30 to which is mounted reflector members 40 and linear collector 50.
In operation, the parabolic reflector 10 is controlled by suitable sun-tracking means which activates motors controlling the azimuth of the reflector about pivot member 23 as well as the altitude of the reflector.
www.freepatentsonline.com /4743095.html   (2273 words)

  
 Parabolic reflector assembled from triangular shaped petals - Patent 3971023
A reflector as in claim 1 wherein the petals form a reflector of substantially paraboloid shape and each petal is generally of parabolic form along its longitudinal axis.
A reflector as in claim 6 wherein the major shape of the petals is slightly curved outward from the longitudinal axis thereof.
The ultimate reflector configuration is determined by the precisely positioned fasteners in each petal or, alternatively in the case of the two-layer configuration wherein the inner layer petals edgewise abutt, by the shape of the abutting petal edges.
www.freepatentsonline.com /3971023.html   (3135 words)

  
 Parabolic reflector   (Site not responding. Last check: 2007-11-06)
The parabolic reflector functions due to the properties of the paraboloid shape: if the of incidence to the inner surface of collector equals the angle of reflection then incoming ray that is parallel to the of the dish will be reflected to central point or " focus ".
The most common applications of the parabolic are in satellite dishes telescopes (including radio telescopes) parabolic microphones and many lighting devices such as spotlights car headlights and LED housings.
The Olympic Flame is lit using a parabolic reflector sunlight.
www.freeglossary.com /Parabolic_mirror   (348 words)

  
 Motor vehicle main beam headlamp incorporating an elliptical reflector and a parabolic reflector - Patent 4680679
A headlamp according to claim 1, wherein said parabolic reflector and said parabolic type sector or sectors are truncated to extend in a vertical direction over a distance H substantially equal to the main opening of the elliptical reflector.
A headlamp according to claim 2, wherein said parabolic reflector and said parabolic type sector or sectors are truncated to extend in a vertical direction over a distance H substantially equal to the main opening of the elliptical reflector.
The present invention improves the above-defined elliptical-parabolic headlamp structure by using at least one sector of a parabolic type reflector to capture light which is not reflected by said elliptical reflector and to project it as a generaly parallel beam to reinforce the on-axis intensity of the main beam from the main parabolic reflector.
www.freepatentsonline.com /4680679.html   (1930 words)

  
 parabolic microphone reflector   (Site not responding. Last check: 2007-11-06)
The parabolic reflector can be from 30 cm to 1 meter (1 to 3 feet) in diameter.
Because of the parabolic shape of the reflector, all sound along a very narrow angle of acceptance will be directed into the microphone.
For parabolic mics, or any type of directional mic used on location, the person controlling the mic should always be wearing a good set of padded earphones connected to the mic's output—especially if subjects are moving.
www.geocities.com /mahdi9631/parabolic.html   (199 words)

  
 Off-set antenna for 1296 MHz (W6/PA0ZN)
It is characteristic of the off-set parabolic reflector assymetric geometry to radiate cross polarized energy with linear polarization("") The cross polarized radiation increases with shorter focal length and larger off-set angle.
These properties cause the beam forming characteristics of a parabolic reflector antenna much the same as a flashlight produces a beam of light when the bulb filament is located at the focal point of the small mirrored parabolic reflector in the flashlight.
The geometry of the off-set fed parabolic antenna may therefore be simply described as the intersection of a cone and a paraboloid, Figure l, shows various useful views of this geometry with simple formulae to calculate all necessary dimensions and angles.
www.nitehawk.com /rasmit/offset.html   (3062 words)

  
 solar4.htm
Parabolic geometry is well known, and it was probably the very first type of solar cooker.
The size of the reflector is directly proportional to the performance of the cooker, and hence, it is a very important parameter.
An asymmetrical parabolic reflector enables a cook to be as close as possible to the cooking vessel.
ashokk_3.tripod.com /solar4.htm   (3150 words)

  
 This is a very basic approach to the Parabolic Sound Reflector Dish   (Site not responding. Last check: 2007-11-06)
Parabolic mirrors are ref-lectors that have the shape of a parabola rotated about the parabola's axis of symmetry.
Parabolic mirrors reflect rays of flight in parallel lines from a light source at the mirror's focus.
The Parabolic sound reflector dish is basically an amplifying unit of sound as a whole.
www.geocities.com /Area51/Labyrinth/3334/aim.html   (3767 words)

  
 Radio-Electronics.Com :: The Parabolic Reflector
In many professional applications these parabolic reflectors are used for satellite as well as for radio astronomy and it is used in many microwave links, often being seen on radio relay towers and mobile phone antenna masts.
These are termed the focal feed reflector where source of radiation is placed at the focal point of the parabola and this is used to illuminate the reflector.
The Cassegrain feed system, although requiring a second reflecting surface has the advantage that the overall length of the antenna between the two reflectors is shorter than the length between the radiating element and the parabolic reflector.
www.radio-electronics.com /info/antennas/parabolic/parabolic_reflector.php   (874 words)

  
 Reflector antennas
Since the reflector is parabolic in the horizontal plane, the energy is focused into a narrow beam.
Since the reflector is narrow in the horizontal plane and wide in the vertical plane, it produces a beam that is wide in the horizontal plane and narrow in the vertical plane.
The cylindrical paraboloid reflector is fed either by a linear array of dipoles, a slit in the side of a waveguide, or by a thin waveguide radiator.
www.tpub.com /neets/book11/46a.htm   (1029 words)

  
 Making a Parabolic Reflector Out of a Flat Sheet   (Site not responding. Last check: 2007-11-06)
The reader should practice with a scaled-down (for example 1:4 or 1:5) model, using a piece of paper.  If you find a parabolic reflector too difficult, a funnel shaped reflector will be a good alternative.  Detailed instructions are given in [2].  However you will need a bigger hole at the bottom of the funnel [1].
As a concrete example, I shall describe the layout of a reflector with 130 mm focal length (f), and 800 mm diameter (D).  All dimensions can be scaled to make reflectors of other sizes.  A square sheet approximately 1000×1000 mm is needed.  It may consist of one, two, or four pieces (fig.
Usually the foil is glued to the reflector.  Most water-based glue will do.  This includes glue made of flour, rice, or starch.  To avoid wrinkles on the foil, the glue must be thin enough that it flows easily.
solarcooking.org /parabolic-from-flat-sheet.htm   (858 words)

  
 Lighting Tech - Reflector Types
Parabolic reflectors have been used in automotive lighting systems almost since the introduction of the automobile, and have been refined during the last 90 years.
The parabolic reflector is most efficient in applications that don’t require sharp cut-offs (such as low-beam light patterns), but allow all of the reflector and lens size to be utilized.
An ellipsoid as a reflector directs the light to a focusing lens that bundles it and projects it onto the road.
www.tirerack.com /accessories/lighting_tech/techpage.jsp?techid=134   (609 words)

  
 Parabolic Templat   (Site not responding. Last check: 2007-11-06)
Parabolic reflectors also loose gain if your finished reflector varies much from the correct curve.
This reflector is the optimal shape for such an antenna.
If you use a solid sheet of aluminum or copper as your reflector, your gain figures may be a little bit higher than these.
www.freeantennas.com /projects/template   (1359 words)

  
 Parabolic Reflectors and Antennas   (Site not responding. Last check: 2007-11-06)
The parabolic reflector is widely used and it is important to understand its reflecting properties.
Conversely, rays emanating from the focus of a parabolic reflector, are all reflected parallel to the axis of the parabola.
Parabolic antennas are also used to emit radiowaves and light.
www.analyzemath.com /parabola/parabola.html   (255 words)

  
 Parabolic reflector with vary transverse width (US4116541)
A parabolic reflector is made of sheet material from a flat pliable elongated blank bent to form a parabolically curved shield shaped member.
The member is parabolically curved longitudinally from end to end and is straight transversely from end to end.
A plurality of parabolically curved members may be disposed side-by-side to increase the area of reflection.
www.delphion.com /details?pn=US04116541__   (195 words)

  
 A Parabolic Solar Cooker for Unattended Cooking   (Site not responding. Last check: 2007-11-06)
The reflector is parabolic.  Its focal length is 178 mm.  It is optimized for angular tolerance, when the sun is at 50° elevation [1].  This angle will be called the default elevation.  Projection of the reflector in the direction of its principal optical axis is an ellipse (fig.
For mass production, the reflector should be molded out of Styrofoam or other types of plastic.  For a prototype it can be made out of a sheet-material by cutting and folding [2].
A parabolic solar cooker suitable for unattended cooking is described.  It features a short focal length, an oversized dark pot, a self-centering potholder, an alignment guide, and a low-profile frame.
solarcooking.org /unattendedparabolic.htm   (1259 words)

  
 ACOUSTIC PROPERTIES OF PARABOLIC REFLECTORS
For the particular geometric form of the parabolic reflector, the sound pressure at the focal region is given by the integral (Little, 1963):
  if the deviation is to be less than one percent, where a is the parabolic constant and L is the wavelength of the sound.  For a value of  a = 10 (typical for the reflectors used), this means that the radius of a facet cannot exceed the square root of the wavelength.
The results are quite comparable to those for the conventional aluminum reflectors, as shown in Figure 3b.  Overall gain averages several decibels less for the fabric reflector because of less efficient reflection.  Due to the imperfect parabolic shape, the limit of directional resolution is somewhat poorer than the 10º found for the conventional aluminum reflector.
home.att.net /~rsl/APPR1.htm   (291 words)

  
 Parabolic_Reflector   (Site not responding. Last check: 2007-11-06)
s less than the aperture of the reflector, making it particularly suitable for recording high frequency sounds such as birdsong.
Incoming sound is directed to the microphone placed at the focus of the parabola-shaped reflector.
The property of the parabolic shape to reflect all sound symmetrically results in multiple
www.sfu.ca /sonic-studio/handbook/Parabolic_Reflector.html   (98 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
Particles were sent from the top of the screen towards the reflector.
They then bounced off of the reflector, with the reflection angle depending on the angle of point of the reflector that they hit.
This is why properly aiming a parabolic reflector is so important.
broken.pc.cz /gallery/parabolicreflector   (268 words)

  
 diyAudio Forums Archive - Parabolic Microphone Reflector
"the increasing efficiency with the frequency" - is this a normal characteristic of parabolic reflectors at audio frequencies ?.
The increasing efficiency with frequency of parabolic reflector is normal at audio frequencies, as well as radio frequencies.
But this is true only for a near strictly parabolic reflector (as SATV dish) not for umbrella or such approximate reflector, which exhibit a maximum efficiency for a particular wavelenght, depending of the actual incurvated form.
www.diyaudio.com /forums/showthread/t-6982.html   (432 words)

  
 Parabolic Reflector   (Site not responding. Last check: 2007-11-06)
What it is, is a fresnel parabolic reflector.
As I fastened it to its wooden support I pulled each strip a little too far round for it to be able to lie flat.
The angle it lies at matches the angle that a similar section of a true parabolic reflector would have -- thus all the angled strips conspire to concentrate sunlight at the focus.
www.ae-zone.org /Designs/altNRG/Parab_reflect.html   (167 words)

  
 A Parabolic Reflector Is Likely Formed On Ocean Level Surface
Gravity field depressions, or geoid parabolic reflectors may be part of the reason why.
These geoid dips, or parabolic reflecting surfaces in the sea surface are known as Walter Depressions, after their discoverer, Clarence Walter.
A mechanism for these failures suggests that the large size of the parabolic sea surface reflectors causes variable path lengths for the satellite reflections as the satellites pass over the regions.
www.pdana.com /AFiles/AF99.html   (734 words)

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