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Do antennas radiate photons?
“The antenna, like the eye, is a transformation device converting
electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. |
Do antennas radiate photons?
On 7/11/2015 11:33 AM, Wayne wrote:
“The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? -- Rick |
Do antennas radiate photons?
rickman wrote:
On 7/11/2015 11:33 AM, Wayne wrote: “The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? There are a lot of people that believe that light is somehow special and the dual nature of all electromagnetic radiation doesn't exist. Most of them base this on the fact that it is impossible with current technology to detect a single photon at frequencies lower than light. -- Jim Pennino |
Do antennas radiate photons?
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Do antennas radiate photons?
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Do antennas radiate photons?
FBMBoomer wrote:
On 7/11/2015 1:04 PM, wrote: rickman wrote: On 7/11/2015 11:33 AM, Wayne wrote: “The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? There are a lot of people that believe that light is somehow special and the dual nature of all electromagnetic radiation doesn't exist. Most of them base this on the fact that it is impossible with current technology to detect a single photon at frequencies lower than light. Radiating RF at the same wavelength as light will produce an electromagnetic field that is not visible to any eye. Babble; light IS electromagnetic radiation. https://en.wikipedia.org/wiki/Light If you think that photons will be converted to electric current on an antenna, try flashing a light on any antenna and check for results. Babble; antennas for light frequencies have been contructed in labs and guess what, they produce a voltage. Research continues to make them a practical solar energy converter. http://arxiv.org/pdf/1204.0330v1.pdf https://en.wikipedia.org/wiki/Nantenna http://www.nature.com/nphoton/journa....2010.237.html Please report back any findings here. :-) I find you are an ignorant babbler. -- Jim Pennino |
Do antennas radiate photons?
On Sat, 11 Jul 2015 08:33:24 -0700, "Wayne"
wrote: The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa. Antennas, Second Edition, 1988, by John D. Kraus. Page 19. Yep, antennas radiate photons. Quantum theory treats RF and light as both a wave and a particle. If you put a pressure gauge behind a flat plate in front of your antenna, you would be able to detect the tiny pressure produced by your RF emissions. The problem is that it's very very very small because the energy decreases linearly with the frequency. When calculating orbital mechanics, light pressure is a major consideration. When building interstellar space craft, "light sails" are a common idea. This should explain it: https://www.khanacademy.org/test-prep/mcat/physical-processes/light-and-electromagnetic-radiation-questions/v/photon-energy# Photon (RF or light) pressure have been measured in the laboratory by using two pressure gauges, blocking RF and light from one gauge, and measuring the differential pressure. The differential measurement cancels external influences, such as gravity, wind, earth movement, etc. In Kraus 3rd edition (2002), the term "photons" appears in questions 2-16-1. 2-16-1. Spaceship near moon. A spaceship at lunar distance from the earth transmits 2 GHz waves. If a power of 10 W is radiated isotropically, find (a) the average Poynting vector at the earth, (b) the rms electric field E at the earth and (c) the time it takes for the radio waves to travel from the spaceship to the earth. (Take the earth-moon distance as 380 Mm.) (d) How many photons per unit area per second fall on the earth from the spaceship transmitter? I couldn't paste the answer because the original, in MS Word format, used characters in the formulas that don't translate to ASCII very gracefully. I'll try to trasnscribble and annotate for clarity: (d) Energy_of_Photon = hf = 6.63*10^-34 * 2*10^-24 J where h=6.63*10^-34 Js (Plank's constant) This is the energy of a 2.5 MHz photon. From (a), PV=5.5*^10-18 Js^-1 m^-2 Therefore, number of photons = (5.5*10^-18 / 1.3*^10^-24) = 4.2*10^6 m^-2 s^-1 (or 1/J) -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
On Sun, 12 Jul 2015 19:54:44 -0700, Jeff Liebermann
wrote: Oops. I goofed in typing in several places. The last part should be: (d) Energy_of_Photon = hf = 6.63*10^-34 * 2*10^9 J = 1.3*10^-24 J where h=6.63*10^-34 Js (Plank's constant) This is the energy of a 2.5 MHz photon. From (a), PV=5.5*10-^18 Js^-1 m^-2 Therefore, number of photons = (5.5*10^-18 / 1.3*^10^-24) = 4.2*10^6 m^-2 s^-1 Hmm... I have no idea where the "2.5 MHz" came from or the strange units for the "number of photons". -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
In article , Jeff Liebermann writes:
Photon (RF or light) pressure have been measured in the laboratory by using two pressure gauges, blocking RF and light from one gauge, and measuring the differential pressure. The differential measurement cancels external influences, such as gravity, wind, earth movement, etc. Maxwell's equations - classical field theory - predict light pressure even without photons and quantum theory. Double slit experiments show interference patterns are followed even by single photons allowed to to pass - exactly as if each photon converted to a wave and portions passed through each slit and thus _the photon interfered with itself_. You really have to observe quantum effects before you can register individual photons. And, with e = h nu, nu being frequency, quantum effects at UHF and below are much harder to see because each photon has such low energy. George |
Do antennas radiate photons?
"Jeff Liebermann" wrote in message ... Yep, antennas radiate photons. +1 There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) |
Do antennas radiate photons?
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:
"Jeff Liebermann" wrote in message .. . Yep, antennas radiate photons. +1 There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
"Jeff Liebermann" wrote in message ... On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote: "Jeff Liebermann" wrote in message . .. Yep, antennas radiate photons. +1 There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. Wouldn't such a gadget be awesome for adjusting antennas! |
Do antennas radiate photons?
On 7/12/2015 7:31 PM, wrote:
FBMBoomer wrote: On 7/11/2015 1:04 PM, wrote: rickman wrote: On 7/11/2015 11:33 AM, Wayne wrote: “The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? There are a lot of people that believe that light is somehow special and the dual nature of all electromagnetic radiation doesn't exist. Most of them base this on the fact that it is impossible with current technology to detect a single photon at frequencies lower than light. Radiating RF at the same wavelength as light will produce an electromagnetic field that is not visible to any eye. Babble; light IS electromagnetic radiation. https://en.wikipedia.org/wiki/Light If you think that photons will be converted to electric current on an antenna, try flashing a light on any antenna and check for results. Babble; antennas for light frequencies have been contructed in labs and guess what, they produce a voltage. Research continues to make them a practical solar energy converter. Of course they produce a voltage. They do not produce light. http://arxiv.org/pdf/1204.0330v1.pdf https://en.wikipedia.org/wiki/Nantenna http://www.nature.com/nphoton/journa....2010.237.html Please report back any findings here. :-) I find you are an ignorant babbler. Yet still, you have not tried your flashlight on any type of antenna to produce a signal. Try harder. Again, for those who understand physics here, a very short wavelength electrical signal sent to an a tuned antenna at the frequency of say red light will produce zero light. It will produce electromagnetic radiation. They are not the same. If you are so sure, just prove us all wrong and win the Nobel Prize in physics. |
Do antennas radiate photons?
FBMBoomer wrote:
On 7/12/2015 7:31 PM, wrote: FBMBoomer wrote: On 7/11/2015 1:04 PM, wrote: rickman wrote: On 7/11/2015 11:33 AM, Wayne wrote: “The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa.” Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? There are a lot of people that believe that light is somehow special and the dual nature of all electromagnetic radiation doesn't exist. Most of them base this on the fact that it is impossible with current technology to detect a single photon at frequencies lower than light. Radiating RF at the same wavelength as light will produce an electromagnetic field that is not visible to any eye. Babble; light IS electromagnetic radiation. https://en.wikipedia.org/wiki/Light If you think that photons will be converted to electric current on an antenna, try flashing a light on any antenna and check for results. Babble; antennas for light frequencies have been contructed in labs and guess what, they produce a voltage. Research continues to make them a practical solar energy converter. Of course they produce a voltage. They do not produce light. You just said "try flashing a light on any antenna and check for results", idiot. Obviously shining a light on an antenna designed for MHz frequencies will not produce an electric current, but shining a light on an antenna designed for THz frequencies will. http://arxiv.org/pdf/1204.0330v1.pdf https://en.wikipedia.org/wiki/Nantenna http://www.nature.com/nphoton/journa....2010.237.html Please report back any findings here. :-) I find you are an ignorant babbler. Yet still, you have not tried your flashlight on any type of antenna to produce a signal. Try harder. I don't have the lab required to build a THz antennn, idiot. Again, for those who understand physics here, a very short wavelength electrical signal sent to an a tuned antenna at the frequency of say red light will produce zero light. It will produce electromagnetic radiation. They are not the same. Shining electromagnetic radiation on an antenna of the appropriate frequency does not produce electromagenetic radiation, it produces an electrical current, idiot. If you are so sure, just prove us all wrong and win the Nobel Prize in physics. I already gave you three links on the subject, idiot. -- Jim Pennino |
Do antennas radiate photons?
FBMBoomer wrote:
snip Again, for those who understand physics here, a very short wavelength electrical signal sent to an a tuned antenna at the frequency of say red light will produce zero light. It will produce electromagnetic radiation. They are not the same. If you can prove they are different then you will be the one in line for a Noblel prize. If you are so sure, just prove us all wrong and win the Nobel Prize in physics. At least one Nobel prize has already been awarded for parts of that proof. (AMI, how many of you are there?) -- Roger Hayter |
Do antennas radiate photons?
"Jeff Liebermann" wrote in message ... One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. Yes it is a question of scale. There is the trick to use a fluorescent light bulb close to an aerial. Energy saving lamps can be quite small . Puting the glass part of one in a microwave oven can be instructive. Don't forget the cup of water. :-) |
Do antennas radiate photons?
On Mon, 13 Jul 2015 08:33:34 -0700, "Wayne"
wrote: "Jeff Liebermann" wrote in message .. . On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote: "Jeff Liebermann" wrote in message ... Yep, antennas radiate photons. +1 There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. Wouldn't such a gadget be awesome for adjusting antennas! Yep. I later realized that it would be marginal for RF circuits because I could only see the components and traces that radiate RF. If the circuit was any good, it wouldn't radiate anything. I also burned some time trying to make an RF equivalent to a liquid crystal sheet. http://www.edmundoptics.com/testing-targets/calibration-standards/temperature-sensitive-liquid-crystal-sheets/1642/ Before thermal imagers became relatively inexpensive, I would place a sheet over the power amplifier or whatever, and be able to see the hot spots. I was also somewhat successful at creating a blurry thermal image, using a small germanium lens and one of these sheets. However, the ideal would be to have a liquid crystal sheet that was sensitive to RF instead of heat. I couldn't find anything that detected low frequency RF directly, but did get some interesting effects by screen printing carbon squares on the thermal sensitive liquid crystal sheets. The carbon would get slightly warm from the RF, and cause the color to change. You can also use thermal crayons to get a similar color change with temperatu http://www.tiptemp.com/Products/Color-Changing-Thermal-Paint-Crayons/TLCSEN464-245-Color-Change-Crayon-Kit Long ago, in High Skool, the instructor waved a neon lamp (NE-2) over a transmission line, so that we could see standing waves. I thought that was cool, but would be even better if a had a row of neon lamps so that I didn't need to move the lamp. So, I built one with about 100 NE-2 lamps. Not only could I see the standing waves, but I could also tune the load for minimum SWR. Today, I could probably built something similar out of the LED strip lighting on rolls: http://www.amazon.com/Triangle-Bulbs-T93007-Waterproof-Flexible/dp/B005EHHLD8 However, it would take more power to light up than the NE-2. At 4.8 watts/meter of LED strip, a 20 meter half wave dipole would require 48 watts to fully light at 10 meter long strip. There are admittedly many things wrong with the aforementioned ideas. None of them will work because of obvious (and not-so-obvious) reasons. That's not the point. One has to start somewhere, and started at "close, but not quite" is as good a place as any. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
In article , Jeff Liebermann writes:
let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. A word: synthetic aperture. Remember the dish arrays in the Jodie Foster movie Contact? You still need the same scale factor - many times the wavelength - but most of a dish array can be air. So with the eyeball analogy, I would first reduce to the size of the pupil - the aperture - and that is perhaps 5 mm. Times 400K gives 2000m for the same theoretical resolution. Of course, for a 2D image you would need an array of antennas spread over a disk of that radius. Or just calculate directly. I think the angular resolution of an array or a telescope in radians is something like 0.22 * wavelength / aperture . Multiply by about 60 to get degrees. So for 1 Ghz (.3m) it's 0.22 * .3m / 2000m, or 33 x 10^-6 radians. About 7 seconds of arc. George |
Do antennas radiate photons?
In article , I wrote:
A word: synthetic aperture. Drone array, anyone? [...] Or just calculate directly. I think the angular resolution of an array or a telescope in radians is something like 0.22 * wavelength / aperture . Oops. That's 1.22 . Still, I don't think it's too bad considering how long ago I learned about synthetic aperture arrays in 2nd year physics. George |
Do antennas radiate photons?
On 14 Jul 2015 03:00:32 -0400, (George
Cornelius) wrote: In article , Jeff Liebermann writes: let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. A word: synthetic aperture. Remember the dish arrays in the Jodie Foster movie Contact? You still need the same scale factor - many times the wavelength - but most of a dish array can be air. So with the eyeball analogy, I would first reduce to the size of the pupil - the aperture - and that is perhaps 5 mm. Times 400K gives 2000m for the same theoretical resolution. Of course, for a 2D image you would need an array of antennas spread over a disk of that radius. Or just calculate directly. I think the angular resolution of an array or a telescope in radians is something like 0.22 * wavelength / aperture . Multiply by about 60 to get degrees. So for 1 Ghz (.3m) it's 0.22 * .3m / 2000m, or 33 x 10^-6 radians. About 7 seconds of arc. George Thanks and interesting. I discarded synthetic aperture imaging because I assumed that either the sensor array or the object being imaged had to be moving roughly perpendicular to each other. That seems to be the case with SAR (synthetic aperture radar). I'll read some more (later) as I have no experience with the technology. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
On 7/13/2015 3:16 AM, George Cornelius wrote:
In article , Jeff Liebermann writes: Photon (RF or light) pressure have been measured in the laboratory by using two pressure gauges, blocking RF and light from one gauge, and measuring the differential pressure. The differential measurement cancels external influences, such as gravity, wind, earth movement, etc. Maxwell's equations - classical field theory - predict light pressure even without photons and quantum theory. Double slit experiments show interference patterns are followed even by single photons allowed to to pass - exactly as if each photon converted to a wave and portions passed through each slit and thus _the photon interfered with itself_. You really have to observe quantum effects before you can register individual photons. And, with e = h nu, nu being frequency, quantum effects at UHF and below are much harder to see because each photon has such low energy. That is the real problem with observing EM photons. IR which has a much shorter wavelength and higher frequency stimulates molecular motion, vibration and spinning which is heat. To see even microwave quanta the apparatus would have to be cooled to very low temperatures to eliminate the interference. Do Josephson junctions work at the level of EM quanta? It has been a long time since I've seen much about them. I don't even remember what they do except that they are QM phenomenon. -- Rick |
Do antennas radiate photons?
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:
There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) Sure there is. After half a century of exposure to RF, my hair is falling out, my hand is shaking, and my bank account depleted. Other people, who were only exposed to light, have not had these things happen. I can only conclude that RF is somehow dangerous and different from light. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
On 7/13/2015 10:59 AM, Jeff Liebermann wrote:
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote: "Jeff Liebermann" wrote in message ... Yep, antennas radiate photons. +1 There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. I think they have that. They are called radio telescope arrays. -- Rick |
Do antennas radiate photons?
On 7/14/2015 3:21 AM, George Cornelius wrote:
In article , I wrote: A word: synthetic aperture. Drone array, anyone? [...] Or just calculate directly. I think the angular resolution of an array or a telescope in radians is something like 0.22 * wavelength / aperture . Oops. That's 1.22 . Still, I don't think it's too bad considering how long ago I learned about synthetic aperture arrays in 2nd year physics. George Hasn't this problem been solved already? We scan the cosmos with large radio antenna arrays to form images of celestial features. -- Rick |
Do antennas radiate photons?
In article , Jeff Liebermann writes:
Thanks and interesting. I discarded synthetic aperture imaging because I assumed that either the sensor array or the object being imaged had to be moving roughly perpendicular to each other. That seems to be the case with SAR (synthetic aperture radar). I'll read some more (later) as I have no experience with the technology. You mean you were planning a 30,000 foot eyeball and no way to aim it? Yes, you are probably right - there would be issues with off-axis imaging, especially if the individual antennas were widely spaced. Unfortunately what I know beyond what I talked about is rather sketchy, but I do know that synthetic apertures are used for optical telescopes. Instead of a single, perfectly polished mirror, you place multiple mirrors somewhat distant from one another and use optical magic (smoke and mirrors?) to put it all together for form an image. Anyway, if you have a telescope mirror with holes in it, you have tradeoffs. I'm guessing that what happens is that there are aliasing effects. If the spacing along, say, the x axis, is s and wavelength is w, you will have alaising - images of off-axis points that appear to be on-axis, for example - and I would expect those to be at angles arcsin ( N w / s ) relative to the normal (read arcsin as "the angle whose sine is") If you want to see something that is off axis, you might be able to leverage this if each antenna is directional and blocks most energy from outside a main lobe narrow enough that, for small N at least, the antanna only picks up signals from one of the aliased angles and blocks the adjacent ones - kind of like an RF amp passband that allows a desired frequency through and not its image frequency. And you might be able to tune the pattern so the nulls in the pattern at least partially null out aliases at the N-1 and N+1 angles, where you would have to have some lobe width adjustment if you wanted to use this technique for more than just a single value of N. If you don't want to use a dish, perhaps you could use a 'Pringles can' antenna with a dipole at the far end of a long cylinder - your "telescope body". You would feed measured magnitude and phase from each antenna to your computer to have it produce an image. And if you were really good, and used a UHF illumination source, you would interfere the illumination source with the received signals and via holographic techniques produce true 3D. Just speculation. But if it's doable I would guess the military has already done it. George |
Do antennas radiate photons?
In article , I wrote:
If you want to see something that is off axis, you might be able to leverage this if each antenna is directional and blocks most energy from outside a main lobe narrow enough that, for small N at least, the antanna only picks up signals from one of the aliased angles and blocks the adjacent ones - kind of like an RF amp passband that allows a desired frequency through and not its image frequency. Actually, the angular spacing increases with N, so if the dish excludes alias images when aligned with the overall "optical axis" then it excludes them when aimed off axis as well. And I am assuming s w, or the formula gives no aliasing at all. George |
Do antennas radiate photons?
On 16 Jul 2015 01:18:17 -0400, (George
Cornelius) wrote: In article , Jeff Liebermann writes: Thanks and interesting. I discarded synthetic aperture imaging because I assumed that either the sensor array or the object being imaged had to be moving roughly perpendicular to each other. That seems to be the case with SAR (synthetic aperture radar). I'll read some more (later) as I have no experience with the technology. You mean you were planning a 30,000 foot eyeball and no way to aim it? That was the Mark I model. Future models will involve some miniaturization. I can't comment on your speculation because (1) I don't know much about synthetic aperture imaging and (2) it won't work anyway. I tried to resolve the first problem by doing some light reading on the topic: https://en.wikipedia.org/wiki/Aperture_synthesis What this demonstrated was that either the telescope of the imaged object needs to be moving. In the case of the optical telescope, it's the earth's rotation that does the moving. I don't think this is compatible with an RF eyeball that fits on my workbench. The 2nd problem is easily solved by what I consider to be a better method. But first, I need to define an objective in electronic terms. What I'm trying to accomplish is build an antenna array that has extremely good resolution, without making it brobdingnagian. If this can be done with just one antenna system, it could be moved around in the form of a flying spot scanner to obtain an image, similar to an optical "flying spot scanner". The basic problem (for me) is how to get obtain good angular resolution from an antenna with not so good angular resolution. I solved this problem with an idea I stole from the WWII Lorenz blind landing system, using 2 directional antennas or one switched antenna. https://en.wikipedia.org/wiki/Lorenz_beam However, I reversed the location of the transmitter and receiver. My system consists of two identical wide "beams" similar to the beam pattern produced by any directional antenna. The angular resolution of the beams causes the amplitude of the signal to vary depending on it's location along the beam pattern, just like any directional antenna. By itself, this angular resolution is useless for imaging. However, if I take two identical antennas, position them at a slight angle from each other, and switch rapidly between rapidly, the line of equal signal level half way between them is VERY narrow. In my testing on VHF, the equal signal null produced was less than 1 degree wide and could probably be improved with a better test setup. I have some sketches and photos buried somewhere and will post them if I can find them. The circuitry is fairly trivial, consisting of a synchronous antenna switch and a synchronized AM demodulator charging two capacitors (one for each antenna), and a comparator. See the block diagram for my AM homer system: http://802.11junk.com/jeffl/AN-SRD-21/ http://802.11junk.com/jeffl/AN-SRD-21/Block%20Diagram.pdf So, how do I produce an image with a null generating derangement? It's somewhat like a photographic negative, but not quite. It's also great for direction finding, but not so great for imaging. Simple inversion of the negative will not produce a usable image. I have some tricks, but all of them rely on the dynamic range of the AM demodulator, which frankly sucks, especially in the presence of noise. Reflections also caused major problems. That's where I stopped working on the idea. Assuming I can extract an image, a rotating or scanning antenna system would only produce a line in one axis, which is hardly an image. So, I propose to store the horizontal line scan, rotate the directional antennas 90 degrees, and scan again. Where the detected (stored) voltages in both axes are equal, it produces an output dot. More can be seen by adding frequency (color) to the output. While at first glance, this might seem like something thrown together using WWII technology, implemented with 1970's hardware, and lacking the benefits of modern acronyms. Yeah, that's probably accurate. Still, it's something that can be built using technology available to the average ham. However, instead of using it to RF image a PCB or an antenna, it might be better to start outdoors by imaging the neighboring RF environment with a rotating antenna on the roof or tower. In theory, one could "see" RF sources and reflections off building and mountains. For indoors, I visualize a motorized X-Y track mounted on the ceiling, with an antenna array similar to a yagi pointing downward towards the device under test. Good luck. If you don't want to use a dish, perhaps you could use a 'Pringles can' antenna with a dipole at the far end of a long cylinder - your "telescope body". I have an aversion to using a waveguide beyond cutoff for anything more than a parabolic dish feed. The main problem is the asymmetry of the pattern caused by the feed being offset from the centerline of the can. See horizontal pattern: http://802.11junk.com/jeffl/antennas/coffee2400/index.html -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
On 7/14/15 4:13 PM, Jeff Liebermann wrote:
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote: There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) Sure there is. After half a century of exposure to RF, my hair is falling out, my hand is shaking, and my bank account depleted. Other people, who were only exposed to light, have not had these things happen. I can only conclude that RF is somehow dangerous and different from light. That's gotta be it, by the infallible principle of Post Hoc Ergo Propter Hoc. |
Do antennas radiate photons?
On Fri, 17 Jul 2015 12:45:52 -0700, Eric Weaver
wrote: On 7/14/15 4:13 PM, Jeff Liebermann wrote: On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote: There is not any proof that RF behaves differently than light. Things are already quite complicated without it :-) Sure there is. After half a century of exposure to RF, my hair is falling out, my hand is shaking, and my bank account depleted. Other people, who were only exposed to light, have not had these things happen. I can only conclude that RF is somehow dangerous and different from light. That's gotta be it, by the infallible principle of Post Hoc Ergo Propter Hoc. Attributing my premature demise to the effects of RF exposure is nothing new. It's done all the time by those that believe that correlation is sufficient evidence to assign causation: http://www.tylervigen.com/spurious-correlations http://tylervigen.com/discover It's a form of inductive logic. That's where one makes a series of observations, and then contrives a generalized conclusion based upon the available observations. For example, I've noticed that most of the hams in the local radio club are officially senior citizens. Therefore ham radio causes accelerated aging. It's all very logical. The only problem is that inductive logic never really provides a proof as there are always alternative explanations. Fortunately, we have an easy test to identify fallacious correlations called Occam's Razor, where the simplest explanation is usually the correct explanation. In my case, RF exposure is a far more complexicated explanation than simple aging. However, I discarded that explanation due to lack of entertainment value. I also find it easier to offer an intentionally complex theory that is easily refuted, so that the simpler theory will be more readily accepted without contest. Had I initially offered the simple theory, it would surely have been met by opposition. I hope this helps. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
rickman wrote:
On 7/11/2015 11:33 AM, Wayne wrote: The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa. Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? No reason better than why a poltergeist should not exist. However, perhaps, a better question might be, "EXACTLY, what is a 'rf photon?'" And, begs the answer to, "What EXACTLY, is a poltergeist?" ....yanno'? |
Do antennas radiate photons?
wrote:
FBMBoomer wrote: On 7/12/2015 7:31 PM, wrote: FBMBoomer wrote: On 7/11/2015 1:04 PM, wrote: rickman wrote: On 7/11/2015 11:33 AM, Wayne wrote: The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa. Antennas, Second Edition, 1988, by John D. Kraus. Page 19. What about it? Is there some reason why RF photons should not exist? There are a lot of people that believe that light is somehow special and the dual nature of all electromagnetic radiation doesn't exist. Most of them base this on the fact that it is impossible with current technology to detect a single photon at frequencies lower than light. Radiating RF at the same wavelength as light will produce an electromagnetic field that is not visible to any eye. Babble; light IS electromagnetic radiation. https://en.wikipedia.org/wiki/Light If you think that photons will be converted to electric current on an antenna, try flashing a light on any antenna and check for results. Babble; antennas for light frequencies have been contructed in labs and guess what, they produce a voltage. Research continues to make them a practical solar energy converter. Of course they produce a voltage. They do not produce light. You just said "try flashing a light on any antenna and check for results", idiot. Obviously shining a light on an antenna designed for MHz frequencies will not produce an electric current, but shining a light on an antenna designed for THz frequencies will. http://arxiv.org/pdf/1204.0330v1.pdf https://en.wikipedia.org/wiki/Nantenna http://www.nature.com/nphoton/journa....2010.237.html Please report back any findings here. :-) I find you are an ignorant babbler. Yet still, you have not tried your flashlight on any type of antenna to produce a signal. Try harder. I don't have the lab required to build a THz antennn, idiot. Again, for those who understand physics here, a very short wavelength electrical signal sent to an a tuned antenna at the frequency of say red light will produce zero light. It will produce electromagnetic radiation. They are not the same. Shining electromagnetic radiation on an antenna of the appropriate frequency does not produce electromagenetic radiation, it produces an electrical current, idiot. If you are so sure, just prove us all wrong and win the Nobel Prize in physics. I already gave you three links on the subject, idiot. THz scanners are being used to detect weapons, etc. However, although they are even being used at some airports, there is much worry, as these frequencies are particularly useful to tear DNA/RNA apart. I don't think anyone has seen them emitting any light, but perhaps the THz freqs are simply shredding the light receptors in the victims/viewers eyes ... lol |
Do antennas radiate photons?
Jeff Liebermann wrote:
On Sun, 12 Jul 2015 19:54:44 -0700, Jeff Liebermann wrote: Oops. I goofed in typing in several places. The last part should be: (d) Energy_of_Photon = hf = 6.63*10^-34 * 2*10^9 J = 1.3*10^-24 J where h=6.63*10^-34 Js (Plank's constant) This is the energy of a 2.5 MHz photon. From (a), PV=5.5*10-^18 Js^-1 m^-2 Therefore, number of photons = (5.5*10^-18 / 1.3*^10^-24) = 4.2*10^6 m^-2 s^-1 Hmm... I have no idea where the "2.5 MHz" came from or the strange units for the "number of photons". Poltergeists? They share a simply amazing number of similarities to "rf photons" ... yanno'? |
Do antennas radiate photons?
"Jeff Liebermann" wrote in message ... One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. Hi As usual others had the same idea .Look here : https://youtu.be/DovunOxlY1k?t=81 |
Do antennas radiate photons?
On Fri, 21 Aug 2015 00:07:43 +0200, "bilou" wrote:
"Jeff Liebermann" wrote in message .. . One of my not so great ideas was to devise a contraption that would let me "see" RF. It certainly would make troubleshooting RF devices much easier. Essentially, it would be a human eye analog implimented with RF components. According to theory, if it works for light, it should also work for RF. At the time, I was working at about 1GHz. Light is about 400 THz. So, all I need is an eyeball that's 400,000 times larger than the human eye. I'll give myself a -1 for the idea. As usual others had the same idea .Look here : https://youtu.be/DovunOxlY1k?t=81 Nope. The AT&T wave demo is a mechanical analogy of wave phenomenon. That's not what I'm looking for. What I want is the ability to look at a radio, power amp, amplifier, etc and actually see the RF leaking from the circuit, or just standing there in the form of standing waves. Like light, I would not expect to see conducted RF, only radiated RF. However, I think there will be enough of both to make the effort worthwhile. Incidentally, if you're into surfing the waves, this should keep you entertained for days: http://www.falstad.com/mathphysics.html (Java required) (Note: Seems to work better when on controlled substances). -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do antennas radiate photons?
"Wayne" wrote in message
... "The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa." Antennas, Second Edition, 1988, by John D. Kraus. Page 19. IMHO, antennae do not radiate photons. and the misunderstanding arises from the photons that are generated from electrons shifting to lower energy orbits around atoms. In tha case of currents within antennae, the energy is the potential energy brought about by compressing electrons against each other, against their inherent mutual repulsion, and is a different mechanism than that which generates photons. |
Do antennas radiate photons?
gareth wrote:
"Wayne" wrote in message ... "The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa." Antennas, Second Edition, 1988, by John D. Kraus. Page 19. IMHO, antennae do not radiate photons. and the misunderstanding arises from the photons that are generated from electrons shifting to lower energy orbits around atoms. In tha case of currents within antennae, the energy is the potential energy brought about by compressing electrons against each other, against their inherent mutual repulsion, and is a different mechanism than that which generates photons. You come a little late to this discussion. Perhaps you would like to explain, on the basis of your theory that there are two kinds of electromagnetic radiation based on the means of their generation, how you tell which kind of em radiation you are observing, the one which also exists as photons or the one that doesn't? Preferably show the answer mathematically. -- Roger Hayter |
Do antennas radiate photons?
"Roger Hayter" wrote in message
... You come a little late to this discussion. Perhaps you would like to explain, on the basis of your theory that there are two kinds of electromagnetic radiation based on the means of their generation, I do not have such a theory. Both are the same type whether generated continuously or photonically. |
Do antennas radiate photons?
"Roger Hayter" wrote in message
... gareth wrote: "Wayne" wrote in message ... "The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa." Antennas, Second Edition, 1988, by John D. Kraus. Page 19. IMHO, antennae do not radiate photons. and the misunderstanding arises from the photons that are generated from electrons shifting to lower energy orbits around atoms. In tha case of currents within antennae, the energy is the potential energy brought about by compressing electrons against each other, against their inherent mutual repulsion, and is a different mechanism than that which generates photons. You come a little late to this discussion. Perhaps you would like to explain, on the basis of your theory that there are two kinds of electromagnetic radiation based on the means of their generation, how you tell which kind of em radiation you are observing, the one which also exists as photons or the one that doesn't? Preferably show the answer mathematically. Insofar as you make a mathematical challenge, perhaps you could deal with some simpler numerical queries ... How many complete cycles make up one of your RF photons? What is the formula for the amplitude envelope of your RF photon? As there is no maser mechanism in a dipole antenna, what is the mechanism that ensures that all of your RF photons are coherent? If the RF photons are not coherent, then why is no amplitude and phase distortion apparent on a single unmodulated carrier wave? |
Do antennas radiate photons?
gareth wrote:
"Roger Hayter" wrote in message ... gareth wrote: "Wayne" wrote in message ... "The antenna, like the eye, is a transformation device converting electromagnetic photons into circuit currents; but, unlike the eye, the antenna can also convert energy from a circuit into photons radiated into space. In simplest terms an antenna converts photons to currents or vice versa." Antennas, Second Edition, 1988, by John D. Kraus. Page 19. IMHO, antennae do not radiate photons. and the misunderstanding arises from the photons that are generated from electrons shifting to lower energy orbits around atoms. In tha case of currents within antennae, the energy is the potential energy brought about by compressing electrons against each other, against their inherent mutual repulsion, and is a different mechanism than that which generates photons. You come a little late to this discussion. Perhaps you would like to explain, on the basis of your theory that there are two kinds of electromagnetic radiation based on the means of their generation, how you tell which kind of em radiation you are observing, the one which also exists as photons or the one that doesn't? Preferably show the answer mathematically. Insofar as you make a mathematical challenge, perhaps you could deal with some simpler numerical queries ... How many complete cycles make up one of your RF photons? The question shows an utter lack of understanding wave-particle duality and makes as much sense as asking how many rib bones are in a gallon of ice cream. What is the formula for the amplitude envelope of your RF photon? The question shows an utter lack of understanding of the particle properties of electromagnetic radiation. A photon has only energy and asking about an amplitude envelope makes as much sense as asking how many rib bones are in a gallon of ice cream. As there is no maser mechanism in a dipole antenna, what is the mechanism that ensures that all of your RF photons are coherent? The question shows an utter lack of understanding of the funcition of an antenna. An antenna has nothing to do with the spectral qualities of the electromagnetic radiation and the question makes as much sense as asking how many rib bones are in a gallon of ice cream. If the RF photons are not coherent, then why is no amplitude and phase distortion apparent on a single unmodulated carrier wave? The question shows an utter lack of understanding of what "coherent" means. A single unmodulated carrier wave is coherent by definition. -- Jim Pennino |
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