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Electron ratio to form a radiation field
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Electron ratio to form a radiation field
On 10 May, 18:09, "Frank's"
wrote: I am aware that the impedance of a particular atmosphere is 377 ohms but that is certainly not a ratio. From:http://whatis.techtarget.com/definit...845268,00.html Frank, you got my attention when you pointed to the above link. I read it a few times and 377 ohms was refered to as Zo. I can't find any reference that states Zo is a ratio. Did you intend to point to another link that specifically points to Zo is a ratio? Surely you are not following in the steps of others where anything can be written right or wrong as long as it creats an augument or distress? You disapoint me! Some in this group are already thinking it is legal for a ratio to have units assigned because of the inference that the link say's it's so which is an untruth and you are perpetuating the spread of untruths. This is similar to another untruth that is being perpetuated with respect to photons just because one person it be so stated. It is getting to the point that if you read it on the net don't believe it unless it can be verified. I think you are confusing a posting by Cecil. Anyway, quoting from "Engineering Electromagnetics" by Nathan Ida, 2nd ed. p 743: "....the reference field is E (an arbitrary choice used in electromagnetics as a convention). Thus we define the ratio between Ex(z) and Hy(z) as eta = Ex(z)/Ey(z) = ...... sqrt(mu/epsilon) [ohms] This quantity is an impedance because the electric field intensity is given in [V/m] and the magnetic field intensity is given in [A/m]. The quantity eta is called the intrinsic impedance or wave impedance of the material.....". Frank O.K. I will go with the majority and bedamned to those who oppose us. I now know what the new or modern mathematics is all about and called for by educationists. I suppose the next generation will be completely at home with these new conventions unlike the mixture that we presently have. Shame that they didn't introduce modern math some 50 years ago which would have shortened this thread by 90%. Regards Art |
Electron ratio to form a radiation field
On 10 May, 13:58, "Frank's"
wrote: "Cecil Moore" wrote in message t... art wrote: I am aware that the impedance of a particular atmosphere is 377 ohms but that is certainly not a ratio. From:http://whatis.techtarget.com/definit...845268,00.html Mathematically, the Zo of free space is equal to the square root of the ratio of the permeability of free space (µo) in henrys per meter (H/m) to the permittivity of free space (o) in farads per meter (F/m): Zo = (µo/o)1/2 = [(1.257 x 10-6 H/m)/(8.85 x 10-12 F/m)]1/2 = 377 ohms (approximately) The exact value of the Zo of free space is 120 pi ohms, where pi is the ratio of the circumference of a circle to its diameter. -- 73, Cecil, w5dxp.com Also the ratio of E/H. [(V/m)/(A/m)] = [ohms]. Frank- Hide quoted text - - Show quoted text - Wow, this is exciting. There is a whole new World out there and we have books that say's it is so. This modern mathematics is going to make thing a lot easier for all book readers. Art |
Electron ratio to form a radiation field
I think you are confusing a posting by Cecil. Anyway, quoting
from "Engineering Electromagnetics" by Nathan Ida, 2nd ed. p 743: "....the reference field is E (an arbitrary choice used in electromagnetics as a convention). Thus we define the ratio between Ex(z) and Hy(z) as eta = Ex(z)/Ey(z) = ...... sqrt(mu/epsilon) [ohms] This quantity is an impedance because the electric field intensity is given in [V/m] and the magnetic field intensity is given in [A/m]. The quantity eta is called the intrinsic impedance or wave impedance of the material.....". Frank O.K. I will go with the majority and bedamned to those who oppose us. I now know what the new or modern mathematics is all about and called for by educationists. I suppose the next generation will be completely at home with these new conventions unlike the mixture that we presently have. Shame that they didn't introduce modern math some 50 years ago which would have shortened this thread by 90%. Regards Art Checking an older textbook: "Electromagnetic Theory" by Julius Adams Stratton, published in 1941, pp 283, 284: "...... the intrinsic impedance of the medium for plane waves is defined by Schelkunoff* as the quantity Zo = sqrt(Z/Y) ....... In free space this impedance reduces to Zo = sqrt(mu/epsilon) = 376.6 ohms. *Schelkunoff, Bell System Tech. J., 17, 17, January, 1938. Where mu and epsilon are defined by Cecil in an earlier posting. Frank |
Electron ratio to form a radiation field
On 10 May 2007 18:28:38 -0700, art wrote:
Shame that they didn't introduce modern math some 50 years ago which would have shortened this thread by 90%. Hi Art, You will have to go back nearly three times that many years, 1864 - to Maxwell once again. The quantity eta is called the intrinsic impedance or wave impedance of the material.....". 120 * pi (roughly 377) Ohms is a fact of nature. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
On 10 May, 19:02, Richard Clark wrote:
On 10 May 2007 18:28:38 -0700, art wrote: Shame that they didn't introduce modern math some 50 years ago which would have shortened this thread by 90%. Hi Art, You will have to go back nearly three times that many years, 1864 - to Maxwell once again. The quantity eta is called the intrinsic impedance or wave impedance of the material.....". 120 * pi (roughly 377) Ohms is a fact of nature. 73's Richard Clark, KB7QHC Heh I am agreeing with you, 377 ohms is a ratio pure and simple. I am now a member of the majority. I used to call 377 ohms an impedance but I am now am agreement with the majority, 377 ohms is a ratio. If Maxwell is part of the majority how can I go wrong. Seems like the blitz got in the way of that jewel being passed on. Art |
Electron ratio to form a radiation field
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Electron ratio to form a radiation field
On 10 May 2007 19:15:32 -0700, art wrote:
I used to call 377 ohms an impedance Hi Art, All impedances are ratios. Nothing has changed since 1864. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
On 10 May, 18:57, "Frank's"
wrote: I think you are confusing a posting by Cecil. Anyway, quoting from "Engineering Electromagnetics" by Nathan Ida, 2nd ed. p 743: "....the reference field is E (an arbitrary choice used in electromagnetics as a convention). Thus we define the ratio between Ex(z) and Hy(z) as eta = Ex(z)/Ey(z) = ...... sqrt(mu/epsilon) [ohms] This quantity is an impedance because the electric field intensity is given in [V/m] and the magnetic field intensity is given in [A/m]. The quantity eta is called the intrinsic impedance or wave impedance of the material.....". Frank O.K. I will go with the majority and bedamned to those who oppose us. I now know what the new or modern mathematics is all about and called for by educationists. I suppose the next generation will be completely at home with these new conventions unlike the mixture that we presently have. Shame that they didn't introduce modern math some 50 years ago which would have shortened this thread by 90%. Regards Art Checking an older textbook: "Electromagnetic Theory" by Julius Adams Stratton, published in 1941, pp 283, 284: "...... the intrinsic impedance of the medium for plane waves is defined by Schelkunoff* as the quantity Zo = sqrt(Z/Y) ....... In free space this impedance reduces to Zo = sqrt(mu/epsilon) = 376.6 ohms. *Schelkunoff, Bell System Tech. J., 17, 17, January, 1938. Where mu and epsilon are defined by Cecil in an earlier posting. Frank- Hide quoted text - - Show quoted text - Jimminy cricket, Are you now saying that 377 ohms is an impedance and not a ratio ? No wonder the threads are so long. Can you pass this info on to those who declare it as a ratio so I can decide with whome I declare allegance to? Harrison and others read it in a book that 377 ohms was a ratio and if it is in a book it must be reliable and this group is never in error. The correctness of this statement has the true efficiency of a yagi on hold because when properly matched losses are 50 % of that energy that was coupled. In a Gaussian array there is no coupling... whow what an achievement the group is pointing out with respect to efficiency. I am a happy camper. Art |
Electron ratio to form a radiation field
On 10 May, 19:25, Richard Clark wrote:
On 10 May 2007 19:15:32 -0700, art wrote: I used to call 377 ohms an impedance Hi Art, All impedances are ratios. Nothing has changed since 1864. 73's Richard Clark, KB7QHC Right on. I understood for once your posting now that you are not including flim flam. If that is what you believe I am comfortable in following suit. Is this now the end of this thread? Do we now have closure? |
Electron ratio to form a radiation field
On 10 May 2007 19:38:25 -0700, art wrote:
Is this now the end of this thread? Hi Art, This latest sub-thread only marks one of your five errors you asked to be identified. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
On 10 May, 20:27, Richard Clark wrote:
On 10 May 2007 19:38:25 -0700, art wrote: Is this now the end of this thread? Hi Art, This latest sub-thread only marks one of your five errors you asked to be identified. 73's Richard Clark, KB7QHC Hmm, go ahead, hopefully somebody will still be hanging around. |
Electron ratio to form a radiation field
= 377 ohms (approximately) Had heard that one wants their stealth fighters to be covered with material that has this impedance. Also heard that any such material that can be manufactured is frequency dependent... |
Electron ratio to form a radiation field
On 10 May 2007 20:56:04 -0700, art wrote:
On 10 May, 20:27, Richard Clark wrote: On 10 May 2007 19:38:25 -0700, art wrote: Is this now the end of this thread? Hi Art, This latest sub-thread only marks one of your five errors you asked to be identified. 73's Richard Clark, KB7QHC Hmm, go ahead, hopefully somebody will still be hanging around. No need to, they are already enumerated elsewhere. What has been remarkable about this thread is that its efficiency has peaked at 20%. - roughly 43.517% above average. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
On Fri, 11 May 2007 04:41:00 GMT, robert casey
wrote: = 377 ohms (approximately) Had heard that one wants their stealth fighters to be covered with material that has this impedance. Also heard that any such material that can be manufactured is frequency dependent... Hi Robert, It's been around for some 20 or 17 years at least and about as heavy as the lead apron you wear for dental XRays. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
robert casey wrote:
= 377 ohms (approximately) Had heard that one wants their stealth fighters to be covered with material that has this impedance. Also heard that any such material that can be manufactured is frequency dependent... If you want to see proof that what you heard isn't so, go to your local EMI test facility and ask to see their anechoic chamber. The one I use is pretty quiet from about 200 kHz up through the microwave range. Under the carbon-loaded foam cones are thick ferrite plates to extend the absorption down to the lower frequencies. You can also get ferrite loaded paint and silicone rubber, both of which have good absorption for several decades of frequency at least. But as Richard says, they're awfully heavy. Roy Lewallen, W7EL |
Electron ratio to form a radiation field
Richard Clark writes:
On 10 May 2007 12:30:13 -0700, wrote: This thread is turning into one of those fantasies of the Boy's magazines of the 1950s: "Build a nuclear reactor on your kitchen table!" Well, that's not just a fantasy, I'm afraid. See the Tale of the Radioactive Boy Scout: http://www.dangerouslaboratories.org/radscout.html I also used to have a picture of Otto Hahn's lab setup when he first split the atom in 1938. It really looked like a few simple instruments arranged on a kitchen table. 73 LA4RT Jon |
Electron ratio to form a radiation field
art wrote:
I used to call 377 ohms an impedance but I am now am agreement with the majority, 377 ohms is a ratio. 377 ohms is both an impedance and a ratio. -- 73, Cecil http://www.w5dxp.com |
Electron ratio to form a radiation field
Sorry people if I step in, but I really don't understand a word of
this thread. (I'm a telecomunnication engineer though). On 11 Mag, 04:15, art wrote: Heh I am agreeing with you, 377 ohms is a ratio pure and simple. I am now a member of the majority. I used to call 377 ohms an impedance but I am now am agreement with the majority, 377 ohms is a ratio. If Maxwell is part of the majority how can I go wrong. Seems like the blitz got in the way of that jewel being passed on. Art R=V/I (ohm's law) is a ratio and its dimensional result is ohms. What's wrong with Zo beeing dimensionally in ohms and beeing a ratio? Thanks and 73 Francesco IZ8DWF |
Electron ratio to form a radiation field
On Fri, 11 May 2007 09:23:10 +0200, LA4RT Jon Kåre Hellan
wrote: Well, that's not just a fantasy, I'm afraid. See the Tale of the Radioactive Boy Scout: http://www.dangerouslaboratories.org/radscout.html Hi Jon, WHEW! I knew fiction had to imitate reality somewhere. 73's Richard Clark, KB7QHC |
Electron ratio to form a radiation field
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