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RSGB RadCom December 2007 Issue
"art" wrote in message news:3bd68052-1537-4b55-a745- snip Oh my, you sound so upset. Your theory used in Eznec was designed around known "reality" because you found the need to add the proviso that there was a sino soidal current at all points on the radiator. Number one, it is not legitamate to add a proviso or a special condition to a known law.( Electrical or Mechanical) Number two It becomes a worse problem when the proviso added is in error. Number three, You should not retain a proviso if it proves incorrect . The fact that present theory has passed the test of time means nothing. The threat of retaliation trumps science when humans are concerned. Gallilao never saw the day that the earth was proven round which stood the test for a very very long time. But you could explain to the world how a sino soidal current passes thru a distributed capacitance and still retain its properties as it encounters every segment. This is per the proviso you have placed with existing Maxwell's laws with respect to your computor program. But no you can't! Until then I don't think you are equipped to say that written theory can be taken as fact.Especially when known laws are twisted so you can gyrate your program to known reality. The old saying still stands, Garbage in will produce garbage out unless the outputs are subject to reprocessing ! Art Unwin...KB9MZ snip Art, I'm sure Roy is quite capable of defending himself against your accusations, but I think you are being a trifle unfair. EZNEC is a simulation designed to predict the performance of an antenna design. Being a simulation, certain assumptions and approximations have to be made in order for it to work. The fact is that in most situations it does provide an accurate prediction of antenna performance. There are some special circumstances where it won't. Integral calculus has been described as one of the greatest advances in mathematical science, but that is still only an approximation method and nobody complains about that. Let's all behave and not argue okay? Best wishes Mike G0ULI |
#42
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RSGB RadCom December 2007 Issue
On Thu, 15 Nov 2007 22:54:14 -0000, "Mike Kaliski"
wrote: I guess you are skeptical that there might be a specific point on an antenna that matches the impedence of free space and thus radiates energy more strongly than the rest of the antenna. Hi Mike, When your energy is frequency based, and your interface is large in terms of wavelength (and anything over 1/10th wave is still large); then trying to home in on a "specific" point is not very specific at all. This is the subject that interests me and I intend to try and establish to my own satisfaction whether this is or is not the case. You will probably be able to approach it by degrees, but as you get closer focus has to be abandoned (classic wavelength vs. physical length diffraction limitation). If this can be established in a scientifically robust manner, then I will present my experimental method, measurements and conclusions for critical examination. I am unfamiliar with work that has been carried out in this field, so I will carry out further searches and reading before embarking on reinventing the wheel. Thanks for the link and the suggestion about plasmonics and fields, I will follow up on that. More towards the RF end of the scale, diffraction limits (being broken) and your interest, consider: http://physicsworld.com/cws/article/print/17398 You can listen to others crow about how "someday" science will catch up, or you can simply see that science has already left that crowd in the dust. The article above (and others found by googling "Boeing, and "negative refractance") will give you an RF material that turns beams in the opposite direction of what would be expected. Our crowing buddies would shrug this off (lack of experience in this matter) because they don't realize that it solves the diffraction limitation. Build your own model and throw RF against it yourself to discover a lens with absolute (not fuzzy) focus. 73's Richard Clark, KB7QHC |
#43
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RSGB RadCom December 2007 Issue
On 15 Nov, 18:25, "Mike Kaliski" wrote:
"art" wrote in message news:3bd68052-1537-4b55-a745- snip Oh my, you sound so upset. Your theory used in Eznec was designed around known "reality" because you found the need to add the proviso that there was a sino soidal current at all points on the radiator. Number one, it is not legitamate to add a proviso or a special condition to a known law.( Electrical or Mechanical) Number two It becomes a worse problem when the proviso added is in error. Number three, You should not retain a proviso if it proves incorrect . The fact that present theory has passed the test of time means nothing. The threat of retaliation trumps science when humans are concerned. Gallilao never saw the day that the earth was proven round which stood the test for a very very long time. But you could explain to the world how a sino soidal current passes thru a distributed capacitance and still retain its properties as it encounters every segment. This is per the proviso you have placed with existing Maxwell's laws with respect to your computor program. But no you can't! Until then I don't think you are equipped to say that written theory can be taken as fact.Especially when known laws are twisted so you can gyrate your program to known reality. The old saying still stands, Garbage in will produce garbage out unless the outputs are subject to reprocessing ! Art Unwin...KB9MZ snip Art, I'm sure Roy is quite capable of defending himself against your accusations, but I think you are being a trifle unfair. EZNEC is a simulation designed to predict the performance of an antenna design. Being a simulation, certain assumptions and approximations have to be made in order for it to work. The fact is that in most situations it does provide an accurate prediction of antenna performance. There are some special circumstances where it won't. Integral calculus has been described as one of the greatest advances in mathematical science, but that is still only an approximation method and nobody complains about that. Let's all behave and not argue okay? Best wishes Mike G0ULI- Hide quoted text - - Show quoted text - But I am behaving. I am sure that both Roy and others who deal with NEC4 will admit that they have played with the truth with respect to antenna programs. I would venture to say that computor programs are good at what they do but it is for all the wrong reasons. Maxwell's laws are just that..Laws. It is mathematically fraudulent to add anything to those laws under the banner of Maxwell. When Roy left the ARRL circle he challenged antena companies to verify their claims with respect to gain. By the same token I am challenging to prove the veracity of the additional statement that a sino soidal current is present at every segment point. Not is it only mathematically illegal to modify a law the addition also defies all electrical laws. A radiator has distributed capacitance and I am not aware that a capacitor will allow the passage of a time varying current, this is what the programing states. He ofcourse can justify why he did this to the satisfaction of all but he cannot justify the insertion of such. Now my antenna operates quite nicely following another aproachyet Roy vehamently derides this new aproach when he himself cannot verify his own actions. Fairness can be seen in different ways. He can be belligerent in analysing my aproach yet at the same time defend an action that he cannot prove to be true. A person always has the right to defend himself especially against those who are mentally challenged. When he provides how distributed capacitance does not affect the time varient that Maxwell states is a titular point of his laws I will readily retract that remark. Until that time I will defend the veracity of my aproach which succesfully produces antennas and arrays in a smaller volume that present theory predicts as impossible. As an adder, I am discussing antennas and not "systems" as Roy would imply. Nothing personal, Like Reagan I like verification since trust does not prove to be enough and I will always defend if I am attacked. Best regards Cheers with a Black and Tan Art Unwin.....KB9MZ...xg |
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RSGB RadCom December 2007 Issue
Mike Kaliski wrote:
... I'm sure Roy is quite capable of defending himself against your accusations, but I think you are being a trifle unfair. EZNEC is a simulation designed to predict the performance of an antenna design. ... Best wishes Mike G0ULI No need for any defense; EZNEC (and other apps) are the "state of the art" as far as hams are concerned--they are more than adequate for our needs. Too bad so many view this/these discussions as an "attack." These "arguments" are only an attempt to peer over the horizon on possible new discoveries and inner workings of antennas. Nothing in my posts are meant to be an attack on EZNEC, Roy, or for that matter, any others and those who use them to construct and place into service the antennas in common use and which perform well. I am sure most others are of a like mind. Arts' feathers have just been ruffled ... something we all have been guilty of--at one time or another. Regards, JS |
#45
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RSGB RadCom December 2007 Issue
On 15 Nov, 19:08, John Smith wrote:
Mike Kaliski wrote: ... I'm sure Roy is quite capable of defending himself against your accusations, but I think you are being a trifle unfair. EZNEC is a simulation designed to predict the performance of an antenna design. ... Best wishes Mike G0ULI No need for any defense; EZNEC (and other apps) are the "state of the art" as far as hams are concerned--they are more than adequate for our needs. Too bad so many view this/these discussions as an "attack." These "arguments" are only an attempt to peer over the horizon on possible new discoveries and inner workings of antennas. Nothing in my posts are meant to be an attack on EZNEC, Roy, or for that matter, any others and those who use them to construct and place into service the antennas in common use and which perform well. I am sure most others are of a like mind. Arts' feathers have just been ruffled ... something we all have been guilty of--at one time or another. Regards, JS Just to clear things. I am not saying that Roy's work does not predict with good accuracy how certain antennas perform. What I am saying it is that it does this despite manipulations for the wrong reasons. Isn't that sort of thing what makes us different to E ham. One can hold his own theories but not by attempting to deride those whose theories differs. There must be room for differences in thought amoung reasonable men or advancement in science is squashed and adherence to written theories could last for ever. A moderator can ensure that present theories remain sacrosant if that is what members desires! Art |
#46
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RSGB RadCom December 2007 Issue
art wrote:
... Just to clear things. I am not saying that Roy's work does not predict with good accuracy how certain antennas perform. What I am saying it is that it does this despite manipulations for the wrong reasons. Isn't that sort of thing what makes us different to E ham. One can hold his own theories but not by attempting to deride those whose theories differs. There must be room for differences in thought amoung reasonable men or advancement in science is squashed and adherence to written theories could last for ever. A moderator can ensure that present theories remain sacrosant if that is what members desires! Art Yer preachin' to the choir. There is more than enough to "prove" there are errors/holes in our present knowledge--well, IMHO, at least. No one is suggesting we just "throw it all away" ... I don't think I am alone--some just remain silent to escape the stones and arrows. I have many more questions than answers, but don't we all? Be interesting in coming back in a hundred years and viewing "em radiation"/antenna theory at that time. You just don't take well to bein' "poked with a stick!" ;-) Regards, JS |
#47
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RSGB RadCom December 2007 Issue
On Thu, 15 Nov 2007 23:35:08 -0500, "Stefan Wolfe"
wrote: "Richard Clark" wrote in message .. . On Thu, 15 Nov 2007 12:29:08 -0000, "Mike Kaliski" wrote: http://home.comcast.net/~kb7qhc/ante...pole/index.htm I don't intend to go too far off topic but the near field results are so strikingly different when you add the ground screen. This is an area that I am not so familiar with The old saw of dipoles not needing a ground (one of those things that makes them so much "better" than verticals) is confounded because they do need a ground - if you want more gain. I don't suppose this is covered in the RSGB RadCom issue (and now we are back on topic). It would seem that the strictly horizontal dipole crowd doesn't need the gain.... The simple fact is that a ground screen reduces ground loss. . At 80M does the program assume that the ground at near field is basically a dielectric instead of a conductor, acting like a large capacitor Basically, more like a resistor. No new science is being marketed here. whereas the screen is a pure conductor? Basically, more like a screen (as in shield). If you want to keep it in the metaphor of "large capacitors" that is what near fields are for. Remove the screen and you have a lossy capacitor. A large inductor could as easily demand center stage and without the screen, we are talking about a lossy inductor. It would seem this would have to be related to the explanation, correct? It sure shows at least one possible advantage of using a lot of radials; it reduces near field (?) Reduces loss. Near fields being reduced is something of an oxymoron. They are still as near as they ever were, the page(s) only illustrate the impedance of near space, expressed in terms of a ratio we commonly call mismatch. In other words, the conventional 377 Ohms of air/vacuum, in the proximity of a conductor, is quite different in value. In some regions, it is represented as being as low as 120 Ohms, in other regions as high as 1200 Ohms. As both these values represent a mismatch ratio of the order of 3:1 (or, contrariwise 1:3), the colors are mapping only the ratios, not the 10-fold variation (that would be too many colors). With finer grain resolution, these values plunge and rise well beyond these arbitrarily restricted values. Someone is sure to exclaim this would only increase NVIS. Yes, the skyward lobe is enhanced, but so is the lobe out to the horizon. A reflector would contribute to the first gain, less loss accounts for both gains. I also analyze verticals and exotic designs (aka fractals) which have mappings that look like tropical storms. 73's Richard Clark, KB7QHC |
#48
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RSGB RadCom December 2007 Issue
Art wrote:
"By the same token I am challenging to prove the veracity of the statement that a sino soidal current is present at every segment point." An antenna is generally a linear passive device meaning that a sinusoidal wave entering an antenna produces sinusoidal fields which induce sinusoidal voltages and currents in the distant receiving antenna. Sinusoidal voltages appear at every point on such an antenna and sinusoidal currents pass over the surface of every point of the antenna. Insulators of course interrupt conduction currents and allow the rise of voltage gradients. Induced currents are produced by the electric field of the wave in the insulation of free space by the displacement (capacitive action) current of an antenna. Maxwell speculated that displacement generated a magnetic field same as conduction did, and that was the secret of radiation. He was proved correct. A magnetic field generated an electric field and an electric field generated a magnetic field so that the two fields locked and traveling together go on ond on forever. Most antennas have two waves traveling in opposite directions, an incident wave and a reflected wave. Both pass through every point on the antenna conductor. A directional coupler can access the wave traveling in one direction while ignoring the wave traveling in the opposite direction. Large variations in voltage appearing on the antenna make the familiar standing wave pattern but this is not a true picture of the individual waves making up the combined wave. The effective values of the incident and reflected waves decline steadily but gradually along the antenna as they travel in opposite directions. A sinusoidal current is present at every segment point and only slowly changes from point to point. Two sine waves of the same frequency always combine at a point to create another sine wave of the same frequency. Best regards, Richard Harrison, KB5WZI |
#49
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RSGB RadCom December 2007 Issue
Richard Harrison wrote:
A magnetic field generated an electric field and an electric field generated a magnetic field so that the two fields locked and traveling together go on ond on forever. ... Best regards, Richard Harrison, KB5WZI From the above, are the two in a constant state of interaction? The magnetic reversing to electric--the electric reversing to magnetic? Or, is their relationship static to one another? Regards, JS |
#50
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RSGB RadCom December 2007 Issue
"Richard Clark" wrote in message ... On Thu, 15 Nov 2007 22:54:14 -0000, "Mike Kaliski" wrote: I guess you are skeptical that there might be a specific point on an antenna that matches the impedence of free space and thus radiates energy more strongly than the rest of the antenna. Hi Mike, When your energy is frequency based, and your interface is large in terms of wavelength (and anything over 1/10th wave is still large); then trying to home in on a "specific" point is not very specific at all. This is the subject that interests me and I intend to try and establish to my own satisfaction whether this is or is not the case. You will probably be able to approach it by degrees, but as you get closer focus has to be abandoned (classic wavelength vs. physical length diffraction limitation). If this can be established in a scientifically robust manner, then I will present my experimental method, measurements and conclusions for critical examination. I am unfamiliar with work that has been carried out in this field, so I will carry out further searches and reading before embarking on reinventing the wheel. Thanks for the link and the suggestion about plasmonics and fields, I will follow up on that. More towards the RF end of the scale, diffraction limits (being broken) and your interest, consider: http://physicsworld.com/cws/article/print/17398 You can listen to others crow about how "someday" science will catch up, or you can simply see that science has already left that crowd in the dust. The article above (and others found by googling "Boeing, and "negative refractance") will give you an RF material that turns beams in the opposite direction of what would be expected. Our crowing buddies would shrug this off (lack of experience in this matter) because they don't realize that it solves the diffraction limitation. Build your own model and throw RF against it yourself to discover a lens with absolute (not fuzzy) focus. 73's Richard Clark, KB7QHC Thank you Richard. I was aware of negative index refraction materials. Now to make them sufficiently broadband and work at optical frequencies... Cheers Mike G0ULI |
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