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Light,Lazers and HF
On Sep 11, 10:37*am, Richard Clark wrote:
On Thu, 11 Sep 2008 06:18:14 -0700 (PDT), Art Unwin wrote: If I have a flash light that is focussed does this wavelength aproach still apply? The reflector (or magnifier lens, take your pick) is on order of at least 1 centimeter. *The light wavelength is on order of 500 nanometers. Ratio = 20,000:1 Beam is generally no narrower than 15 degrees. *At a distance of, say, 6 feet, that beam would cover a diameter of 18 inches. *Nothing like a Lazer (sic) if that is the goal. 73's Richard Clark, KB7QHC I see no basis for the inclusion of wavelengths when one is not using a straight radiator A straight radiator requires one type of reflector an array that is condensed to a smaller volume requires a reflector that is based on the propagation from that radiator. If propagation flares out then you can calculate dish size via WL. If propagation is of a different form then the dish must be designed accordingly.The important factor as I see it is the mode of propagation and what area is required at a distance to account for tha propagation mode. If one starts with a lazer then the reflecting surface need not be larger than the initiating beam area assuming zero scattering. Your thinking is based solely on the state of the art via reading matter. You need to go back in physics to the four forces of the standard model to analyse this question on the basis of the unification theory which is all conclusive where one can determine relative ejection paths from the radiator. The latter may well gyrate to WL I suppose |
Light,Lazers and HF
On Sep 10, 10:56*pm, wrote:
On Sep 10, 10:29*pm, Art Unwin wrote: On Sep 10, 9:23*pm, Art Unwin wrote: On Sep 10, 8:45*pm, wrote: Art Unwin wrote: What is the main factor that prevents HF radiation from focussing for extra gain? Money. If you can afford to build a 20m parabola about 2,000 feet in diameter and the place to mount it, you'll get lots of gain. -- Jim Pennino Remove .spam.sux to reply. Then are you saying it is the antenna size that is the main factor?. So my antenna which is physically small can be focussed on a dish which would provide straight line radiation or a radiation beam? Working on a single element on the ground with a optimizer instead of a half sphere I got a straight vertical line at the sides which suggested a gun barrel radiation with a perfect earth as the reflector. Gain was around 8db vertical which is why the question regarding focussing! If it was properly focussed the gain should be more. 2000 foot dish seems somewhat odd, probably based on a "straight" wavelength and not a small volume in equilibriumas the directer right? Art Let me ask the question another way. Whether it is believed or not, if a 80 Metre antenna was compressed to the size of a couple of shoe boxes would the dish be reduced in size accordingly? Regagards Art- Hide quoted text - - Show quoted text - No. The shoebox size antenna would approximate an isotropic if it did radiate. It would still have to be placed at the focal point of a very large parabola due to the size of the wave length. Such an antenna, I believe, on the island of Puerto Rico (the SETI antenna) although it is currently used primarily as a receiving antenna. That parabola is positioned to have a very high radiation angle and might not be be that good for terrestrial DX. The antenna at PR has a stable reflector and a moveable receiver thus the take off angle depends on the angular position of the receiver and the center of the reflector. The receiver is moved regularly so the sky can be traversed for listening. This was the idea when the antenna was set up initialy by Princeton University before they gave up possesion of it. With respect to WL no facts have been presented to support that fact. If you go back to the arbitrary border analysis a force thru the paper of the center of the border will present resultant forces around the outside of the border representing ripples on water in wave like fashion, that does not correlate to the ejection of a particle thru a fissure in the border. Mixing apples and oranges no less Nuf said |
Light,Lazers and HF
On Sep 10, 10:05*pm, wrote:
Art Unwin wrote: On Sep 10, 8:45?pm, wrote: Art Unwin wrote: What is the main factor that prevents HF radiation from focussing for extra gain? Money. If you can afford to build a 20m parabola about 2,000 feet in diameter and the place to mount it, you'll get lots of gain. -- Jim Pennino Remove .spam.sux to reply. Then are you saying it is the antenna size that is the main factor?. Of course. Everyone knows the gain of a parabola is directly proportional to the size in wavelengths, or: Not so!, That is totally depended on the conditions assumed or assumptions made such as the shape and size of the emmitter from which scattering of radiation can be calculated i.e. the shape of the cone if the scattering is confined to a specific angle. If radiation is determined from all four forces of the standard model then the radiator can be any size, shape or elevation as long as it is in equilibrium, thus the "weak" force must be taken into consideration. Period . This also means one must think beyond the books where radiation is a mystery and not fully understood by the masses. Progress can only be made by following the Universal laws via first principles and not by selected extractions of formula from reading matter. Don't they parrot that in the Universities of the U.S.A.? Best regards unless you are in a nasty mood Art Unwin KB9MZ..........xg G=10*log k(pi*D/L)^2 Where G= gain in DB over an isotropic, k ~ .55 for most real parabolas, D is the diameter, and L is the wavelength (wavelength and diameter in the same units. So a 2,000 foot parabola on 20m would have just about 58db gain. -- Jim Pennino Remove .spam.sux to reply. |
Light,Lazers and HF
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Light,Lazers and HF
Art Unwin wrote:
On Sep 10, 10:05?pm, wrote: Art Unwin wrote: On Sep 10, 8:45?pm, wrote: Art Unwin wrote: What is the main factor that prevents HF radiation from focussing for extra gain? Money. If you can afford to build a 20m parabola about 2,000 feet in diameter and the place to mount it, you'll get lots of gain. -- Jim Pennino Remove .spam.sux to reply. Then are you saying it is the antenna size that is the main factor?. Of course. Everyone knows the gain of a parabola is directly proportional to the size in wavelengths, or: Not so!, Well, yes, I guess that's true as only those with an education in electromagnetics would know that. So I doubt many participants in rec.folk-dancing would know that, but this isn't rec.folk-dancing, though some posters here do seem to dance around a lot. -- Jim Pennino Remove .spam.sux to reply. |
Light,Lazers and HF
On Thu, 11 Sep 2008 09:38:46 -0700 (PDT), Art Unwin
wrote: On Sep 11, 10:37*am, Richard Clark wrote: On Thu, 11 Sep 2008 06:18:14 -0700 (PDT), Art Unwin wrote: If I have a flash light that is focussed does this wavelength aproach still apply? The reflector (or magnifier lens, take your pick) is on order of at least 1 centimeter. *The light wavelength is on order of 500 nanometers. Ratio = 20,000:1 Beam is generally no narrower than 15 degrees. *At a distance of, say, 6 feet, that beam would cover a diameter of 18 inches. *Nothing like a Lazer (sic) if that is the goal. I see no basis for the inclusion of wavelengths when one is not using a straight radiator Read your own question. There is no such thing as a "straight radiator" of light. There is everything to do with wavelength or you could never see light. 73's Richard Clark, KB7QHC |
Light,Lazers and HF
On Sep 11, 2:55*pm, Richard Clark wrote:
On Thu, 11 Sep 2008 09:38:46 -0700 (PDT), Art Unwin wrote: On Sep 11, 10:37*am, Richard Clark wrote: On Thu, 11 Sep 2008 06:18:14 -0700 (PDT), Art Unwin wrote: If I have a flash light that is focussed does this wavelength aproach still apply? The reflector (or magnifier lens, take your pick) is on order of at least 1 centimeter. *The light wavelength is on order of 500 nanometers. Ratio = 20,000:1 Beam is generally no narrower than 15 degrees. *At a distance of, say, 6 feet, that beam would cover a diameter of 18 inches. *Nothing like a Lazer (sic) if that is the goal. I see no basis for the inclusion of wavelengths when one is not using a straight radiator Read your own question. *There is no such thing as a "straight radiator" of light. *There is everything to do with wavelength or you could never see light. 73's Richard Clark, KB7QHC If you say so and are comfortable with that then stick with it ! My thoughts are with the reflector and it's design |
Light,Lazers and HF
On Sep 11, 2:05*pm, wrote:
Art Unwin wrote: On Sep 10, 10:05?pm, wrote: Art Unwin wrote: On Sep 10, 8:45?pm, wrote: Art Unwin wrote: What is the main factor that prevents HF radiation from focussing for extra gain? Money. If you can afford to build a 20m parabola about 2,000 feet in diameter and the place to mount it, you'll get lots of gain. -- Jim Pennino Remove .spam.sux to reply. Then are you saying it is the antenna size that is the main factor?. Of course. Everyone knows the gain of a parabola is directly proportional to the size in wavelengths, or: Not so!, Well, yes, I guess that's true as only those with an education in electromagnetics would know that. So I doubt many participants in rec.folk-dancing would know that, but this isn't rec.folk-dancing, though some posters here do seem to dance around a lot. -- Jim Pennino Remove .spam.sux to reply. Yes Jim. Unless one accepts the weak force for what it is, what creaates it and what it does for overall vector angles discussion is moot. For instance the emmitter cannot be parallel to the axis of the reflector, it must be tilted per the recognition of the weak force otherwise the mathematic and symbols such as equal or zero are meaningless. You must begin with symetry or equilibrium. You surely must know Jim that many hams do not have an understanding of electromagnetics only on how a microphone is used or a particular part of ham radio where their interests are, The hobby is all inclusive and where one expertise does not necessarilly spill over to the other except only in the eyes of the speaker |
Light,Lazers and HF
On Sep 11, 2:55*pm, Richard Clark wrote:
On Thu, 11 Sep 2008 09:38:46 -0700 (PDT), Art Unwin wrote: On Sep 11, 10:37*am, Richard Clark wrote: On Thu, 11 Sep 2008 06:18:14 -0700 (PDT), Art Unwin wrote: If I have a flash light that is focussed does this wavelength aproach still apply? The reflector (or magnifier lens, take your pick) is on order of at least 1 centimeter. *The light wavelength is on order of 500 nanometers. Ratio = 20,000:1 Beam is generally no narrower than 15 degrees. *At a distance of, say, 6 feet, that beam would cover a diameter of 18 inches. *Nothing like a Lazer (sic) if that is the goal. I see no basis for the inclusion of wavelengths when one is not using a straight radiator Read your own question. *There is no such thing as a "straight radiator" of light. *There is everything to do with wavelength or you could never see light. 73's Richard Clark, KB7QHC If you say so and are comfortable with that then stick with it ! My thoughts are with the reflector and it's design |
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