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Narrow lobe of a yagi
As gain increases with a yagi design the forward
lobe narrows . With high gain yagi's the lobe becomes so narrow it is deemed to be a hinderence instead of an advantage. To overcome this perceived problem one has to know what causes it. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? End effects perhaps! Regards Art |
On Sun, 27 Mar 2005 16:20:58 GMT, "
wrote: As gain increases with a yagi design the forward lobe narrows . Let's certainly hope so. With high gain yagi's the lobe becomes so narrow it is deemed to be a hinderence instead of an advantage. Huh, I didn't know this...for several decades now I've thought it was an advantage. For example my EME friends and I have always believed that focusing the available transmit power on the moon on transmit and rejecting stellar background noise on receive was desirable. How did we go so wrong? |
On Sun, 27 Mar 2005 16:20:58 GMT, "
wrote: To overcome this perceived problem one has to know what causes it. Hi Art, Replace the defective yagi with an omni. To re-obtain gain without perceived problem - add amplification. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? Sinus pressure. 73's Richard Clark, KB7QHC |
In article K3B1e.8558$NW5.7100@attbi_s02,
wrote: As gain increases with a yagi design the forward lobe narrows . With high gain yagi's the lobe becomes so narrow it is deemed to be a hinderence instead of an advantage. To overcome this perceived problem one has to know what causes it. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? End effects perhaps! Conservation of energy. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
"Wes Stewart" wrote in message ... On Sun, 27 Mar 2005 16:20:58 GMT, " wrote: As gain increases with a yagi design the forward lobe narrows . Let's certainly hope so. But if you knew the answer you could then use the knoweledge to extend the narrowing to provide more gain. All is known about antennas isn't it? It doesn't with my antenna where the lobe gets larger as radiation is deflected to the forward direction. Obviously with a yagi cancellation is occuring as well as addition. With high gain yagi's the lobe becomes so narrow it is deemed to be a hinderence instead of an advantage. Huh, I didn't know this...for several decades now I've thought it was an advantage. You are not alone as I thought it meant quieter contacts but it is said (ARRL publication) that it then becomes more difficult to aim, ala the rombic. That's why I see my antenna's flattening of the main lobe without loss in beam width an advantage. For example my EME friends and I have always believed that focusing the available transmit power on the moon on transmit and rejecting stellar background noise on receive was desirable. How did we go so wrong? But back to the question. ------------------------------------- Do you know what creates the narrowing of the main lobe ? It only takes one diffinitive post from a real guru to explain and then the others will follow. Until the real guru comes forward with an explanation all others will procrastinate and avoid the question without giving a hint that they do not know and are awaiting the explanation from a real guru. If you actually know Wes then jump in so others may follow. Regards Art .. |
Richard
Why do you feel compelled to post when you apparently do not know the answer. Your response is pure rubbish Why not wait for the real guru to post so you can float in on his or her's coatails ? You seem to have a penchant for posting in such oblique language in the hope that others will see you as possibly knoweledgable but not understood by the lesser educated. Your degree in Shakespeare has sure muddled your thinking with respect to engineering. Art "Richard Clark" wrote in message ... On Sun, 27 Mar 2005 16:20:58 GMT, " wrote: To overcome this perceived problem one has to know what causes it. Hi Art, Replace the defective yagi with an omni. To re-obtain gain without perceived problem - add amplification. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? Sinus pressure. 73's Richard Clark, KB7QHC |
On Sun, 27 Mar 2005 17:28:25 GMT, "
wrote: Richard Why do you feel compelled to post Hi Art, Because straightforward, simple answers seem to baffle you so outright. See? Each and every post offers what is YOUR responsibility to discuss, and by your choice you litter the landscape with thrashing over style instead of content: Your response is pure rubbish Let's call it entangled correspondence. Really, Art, you need to go back to your disclaimers with each posting so we can tell when you aren't serious. Why not wait for the real guru to post so you can float in on his or her's coatails ? -Whew!- And here I thought you had reserved your venom of "guru" for me alone. Thanx, that makes me feel so much better that you have elevated me above that ill-bred population you so love to spit on. others will see you as possibly knoweledgable but not understood by the lesser educated. Well, let's test that by returning to the topic and see which side you occupy: Now, do you dispute that sinus pressure DOES NOT create narrowing of frontal lobes? Even the lesser educated know this for a fact, Art. Are you suggesting that perceived problems of yagis cannot be cured with an omni with amplification? Something tells me you already had an answer for that hidden up your sleeve (without data of course but perfectly proven with chords and tangents). I await your Euclidean gymnastics. ;-) 73's Richard Clark, KB7QHC |
"Dave Platt" wrote in message ... In article FUB1e.8710$NW5.8590@attbi_s02, wrote: It doesn't with my antenna where the lobe gets larger as radiation is deflected to the forward direction. There is a harsh limit, imposed by physics, as to how much gain that approach can give you. Agreed... Do you know what those limits are ? If all of the energy from one hemisphere is redirected into the other hemisphere, and if the forward-direction pattern shape does not change (the forward lobe is not narrowed), then you have a forward gain of 3 dB (2:1 power ratio increase). You *cannot* have more, as this would require that the antenna be radiating more power than it receives from its input. Absolutely incorrect. If I place the air of two balloons ,which reflect the figure eight,into one single balloon and where the laws of partial pressures do not intervene then you will have a balloon that is round and not elongated as the antenna books would have you suggest. "Gain" is a term used to to quantify a small portion of the energy contained in the mythical ball of energy. Since the collection of energy comes from different directions and phases the energy collection is layered depending on the influence of the earth. Thus the layers of radiation are distorted where one layer can be squeezed outwards further than other layers, thus the terminology of "gain" If you are going to interelate the terms of "gain" and "power" then you must define the parameters used to allow that. A Moxon antenna is, to a first approximation, a pretty good example of this approach - it has very little energy in the rear hemisphere, and a broad forward lobe. There are various two-driven-element array designs which achieve a similar pattern and result. And the resulting "gain" is ....what? I have difficulty in getting beyond 16 dbi as any additional energy from the rear has very little effect on the diameter of the frontal lobe. Obviously with a yagi cancellation is occuring as well as addition. You are trying to draw a distinction between "deflection" and "cancellation" which I believe is invalid. Both are simply ways of describing the result of the "sum of vectors" effects of having energy from multiple radiators (driven or passive) combining in different phases at different locations. Same math, two different words. Yes I agree because of conservation laws e.t.c . When cancellation occurs then energy creats energy in another direction similar to pulling steel apart in tension (or using compression) the steel becomes narrower before severing occurrs. This thinning or "waisting" is created by the additional forces created at 90 degrees to the tensile forces and where the break actually occurrs at 45 degrees and not at right angles. Do you know what creates the narrowing of the main lobe ? Conservation of energy *requires* that the main lobe be narrowed, if you wish to achieve more gain than you can get by simply redistibuting the rear-ward energy in the forward direction. This is what you alluded to before and it is still incorrect What "requires" what ? And how is this conclusion generating an elongated lobe? A super-high-gain antenna *cannot* have a wide, uniform beam-width in both azimuth and elevation. Don't know how you can say that unless somehow you generated a single lobe. Now that would be interesting As usual for your postings, Art, it's impossible to tell whether your claims for your antenna are plausible, because you refuse to disclose *anything* (either the invention, or the results you claim) in any halfway-tanglible form (e.g. models, specific numbers, etc.). My antenna is somewhat related thus my interest in what creates an elongated lobe which is formed using Yagi principles. The question however, is specifically related to Yagi's and its narrowed lobes. Do you know what it is that creats an elongated lobe on a high gain yagi i.e not totally round.? Nothing more, nothing less. Regards Art Until you do, I really think it would be to everyone's relief if you'd follow through with your recent statement that you were going to stop posting. You're achieving no good result for yourself by contining as you are. I have not posted as you have inferred. The question is about Yagi design AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
On Sun, 27 Mar 2005 18:59:42 GMT, "
wrote: the problem: My antenna is somewhat related thus my interest in what creates an elongated lobe the answer: which is formed using Yagi principles. Hi Art, Your question already answers your question. You have a tendency to just blow right on taking no notice of this to create the SAME question again: The question however, is specifically related to Yagi's and its narrowed lobes. Do you know what it is that creats an elongated lobe on a high gain yagi i.e not totally round.? formed using Yagi principles. (to quote you) Nothing more, nothing less. Exactly. Now, are we going to be treated by another round of your complaints about Shakespeare and the quality of gurus; or are you going to stick with technical discussion and respond to the obvious points? 73's Richard Clark, KB7QHC |
wrote:
As gain increases with a yagi design the forward lobe narrows. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? ______________________ A good analogy that needs no math to understand is that of squeezing an inflated balloon from its normally spherical shape into whatever shape is more appropriate for the application. There is a given volume of air in that balloon. If you want the surface of the balloon to extend further from the origin of its original sphere, the new shape must be narrower in one or more planes than the original shape. The shape changes can come from squeezing the balloon (pattern) horizontally, vertically, or in combination -- which, in antenna hardware is accomplished by an appropriate array of, and feed system for, its radiating elements. RF |
wrote:
So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? The narrowing of the forward lobes is caused by constructive interference during superposition of EM waves. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
In message K3B1e.8558$NW5.7100@attbi_s02, "
writes As gain increases with a yagi design the forward lobe narrows . With high gain yagi's the lobe becomes so narrow it is deemed to be a hinderence instead of an advantage. To overcome this perceived problem one has to know what causes it. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? End effects perhaps! My tuppence worth It is a fundamental energy conservation effect. There is an invariant A * Omega , where A is the capture area of the antenna, proportional to gain and Omega is the solid angle of the lobe. So as A goes up, Omega must come down. One way to reduce the effect is to use a number of vertically stacked low gain yagis. The lobe becomes narrow in the vertical plane , but remains broad in the horizontal plane. This is fairly common technique for VHF/UHF contesters, where a narrow horizontal beam can cause missed contacts Brian -- Brian Howie |
Richard.
No one has come up with a explanation BUT there are real gurus out there, It's just that those who qualify as gurus have just thinned out a bit. The question still pertains to Yagis and the narrowing of lobes You have posted twice now and added nothing that relates to a possible answer. Tho there are many who perceive themselves as experts and then consistently show what they really are. I can think of one or two who can really address this question with a logical answer. Cecil, Roy and a couple of others qualify and have yet to respond You have disqualified yourself based on your responses, so like myself you will have to wait to learn. Yagi's have been studied in depth and for many years by many tho apparently not by you or others that have replied so far. Place your bets on who is the real guru of this group that comes forward to explain with logic and to the point You Richard, can read your old QST's in a hurry and surely find the answer to get back into the ratings as I don't think that new knoweledge is around the bend, just a small manipulation of "old" knoweledge will surely suffice. Think "end effect" and "none- resistive residuals" along coupled radiating elements for starters.If that draws a blank then assuredly you wear no clothes Art "Richard Clark" wrote in message ... On Sun, 27 Mar 2005 18:59:42 GMT, " wrote: the problem: My antenna is somewhat related thus my interest in what creates an elongated lobe the answer: which is formed using Yagi principles. Hi Art, Your question already answers your question. You have a tendency to just blow right on taking no notice of this to create the SAME question again: The question however, is specifically related to Yagi's and its narrowed lobes. Do you know what it is that creats an elongated lobe on a high gain yagi i.e not totally round.? formed using Yagi principles. (to quote you) Nothing more, nothing less. Exactly. Now, are we going to be treated by another round of your complaints about Shakespeare and the quality of gurus; or are you going to stick with technical discussion and respond to the obvious points? 73's Richard Clark, KB7QHC |
"Richard Fry" wrote in message ... wrote: As gain increases with a yagi design the forward lobe narrows. So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? ______________________ A good analogy that needs no math to understand is that of squeezing an inflated balloon from its normally spherical shape into whatever shape is more appropriate for the application. There is a given volume of air in that balloon. If you want the surface of the balloon to extend further from the origin of its original sphere, the new shape must be narrower in one or more planes than the original shape. The shape changes can come from squeezing the balloon (pattern) horizontally, vertically, or in combination -- which, in antenna hardware is accomplished by an appropriate array of, and feed system for, its radiating elements. Right..... so what creats it, this "squeezing" that you talk about and from where does this "squeezing force come from in an "appropiate"array? That's what I was asking not a discussion of what the Yagi array produces. Why does the lobe narrow? Art RF |
Yes Cecil I can go along with that otherwise the resultant volume would be
spherical. What is the scenario that encapsulates this "constructive interference" event? Is it residual reactance where its underpinning reside? Art Art "Cecil Moore" wrote in message ... wrote: So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? The narrowing of the forward lobes is caused by constructive interference during superposition of EM waves. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
"Cecil Moore" wrote in message ... wrote: So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? The narrowing of the forward lobes is caused by constructive interference during superposition of EM waves. -- 73, Cecil http://www.qsl.net/w5dxp Darn - I thought it was pure magic. Now we hear all about induced currents and interference patterns cancelling in the rearward and the sides, but constructively interferring in the forward direction. All in an attempt to become the chosen guru of the original poster. If nominated, I will not run - if elected - I will not serve. |
In article uoD1e.110018$Ze3.66917@attbi_s51, wrote: There is a harsh limit, imposed by physics, as to how much gain that approach can give you. Agreed... Do you know what those limits are ? Sure. The simplest way to state it is "the total amount of power delivered by the antenna, summed over all of the possible angles of radiation, must equal the total amount of power radiated by the antenna." If all of the energy from one hemisphere is redirected into the other hemisphere, and if the forward-direction pattern shape does not change (the forward lobe is not narrowed), then you have a forward gain of 3 dB (2:1 power ratio increase). You *cannot* have more, as this would require that the antenna be radiating more power than it receives from its input. Absolutely incorrect. If I place the air of two balloons ,which reflect the figure eight,into one single balloon and where the laws of partial pressures do not intervene then you will have a balloon that is round and not elongated as the antenna books would have you suggest. "Gain" is a term used to to quantify a small portion of the energy contained in the mythical ball of energy. Since the collection of energy comes from different directions and phases the energy collection is layered depending on the influence of the earth. Thus the layers of radiation are distorted where one layer can be squeezed outwards further than other layers, thus the terminology of "gain" Jeez, Art, do you have any idea of just how thoroughly your response qualifies as "Authentic frontier gibberish" (as a Mel Brooks character once said)? I'm sorry, guy, but I believe that you are trying to stretch analogies far beyond the point where they actually apply to the physical phenomena we're discussing. Your concept of "layers of radiation" (as applied to the gain pattern of an antenna) simply doesn't add up. If you are going to interelate the terms of "gain" and "power" then you must define the parameters used to allow that. OK, let's do just that. "Power" is very well defined - it's the rate at which energy is delivered. Pick your units for energy and time as you choose. It's conventional to use watts for power, joules for energy and seconds for time. One watt, equals a rate of energy delivery of one joule per second. "Gain" is a ratio. In discussions dealing with antennas, the gain describes the ratio between the amount of power delivered by a given antenna in a given direction, to the amount of power delivered in that same direction by a "reference" antenna (a dipole in the case of a dBd gain number, and an "isotropic" antenna in the case of a dBi gain number). The gain figures in dB are logarithmic. Those are the definitions everyone uses, I believe. If you, personally, are using different definitions than these, then our discussion (you vs. everyone else) should probably stop right here. Here's my rationale behind the statement I made about the limitations of your approach: - An isotropic antenna has a gain of 0 dBi, by definition. - If you "cut off" the entire rear side of an isotropic antenna's pattern (so that it radiates no power backwards), and precisely overlay this power (energy flow) onto the forward half, you'll end up with a "half-isospheric" antenna. It's radiating exactly the same amount of power, but over only half as much target area. The power (energy flow) towards each point in that targeted hemisphere will be exactly twice as much as in the isotropic antenna. This antenna has a gain of 3 dBi plus a hair. It cannot have *more* gain in any direction (more power into a sub-portion of the hemisphere) unless it has *less* gain in another portion of that hemisphere... in other words, unless is starts exhibiting some form of lobing/nulling. If it *could*, it would be trivial to demonstrate that the antenna was delivering more power (more energy over time) into its loads, than it was accepting from its transmitter. The same line of logic applies even if you start with a dipole. If you begin with a dipole, and then magically "deflect" all of the power from the rear towards the front and overlay the patterns exactly, you'll exactly double the power in each forward-lying half of the sphere, and create a gain of 3 dB over the dipole. In order to have *more* forward gain in any direction in the forward direction, you must necessarily have *less* in another, and this either narrows the pattern in the forward direction or creates partial or complete nulls. To claim otherwise, is to claim an antenna which can be shown to deliver more power than it accepts as input... in other words, one which violates the conservation of energy. The same basic rule applies for any situation in which you take a bidirectional antenna (one which has a symmetrical forward-and- backward gain pattern) and then "deflect" all of the rearward energy into a forward direction. This will gain you at most 3 dB over the basic gain pattern of the antenna you started with. Any further maximum forward gain, over the antenna you were starting with, can *only* be achieved by decreasing the gain somewhere in the pattern (narrowing or weakening the main lobe or one of the sidelobes). A Moxon antenna is, to a first approximation, a pretty good example of this approach - it has very little energy in the rear hemisphere, and a broad forward lobe. There are various two-driven-element array designs which achieve a similar pattern and result. And the resulting "gain" is ....what? According to Cebik's web site, a 2-meter Moxon shows a maximum forward gain of about 10.7 dBi, or a bit more than 8 dB over a dipole. One could gain at most 3 dB due to the forward "deflection" of rear- hemisphere energy, and hence the remaining 5 dB or so of gain over a dipole must come from a narrowing of the antenna's pattern in either azimuth or elevation or both. Yes I agree because of conservation laws e.t.c . When cancellation occurs then energy creats energy in another direction similar to pulling steel apart in tension (or using compression) the steel becomes narrower before severing occurrs. This thinning or "waisting" is created by the additional forces created at 90 degrees to the tensile forces and where the break actually occurrs at 45 degrees and not at right angles. Art, I think your analogies between radiation patterns, balloons, stretching metal, etc. are leading you astray more than they are helping you. Conservation of energy *requires* that the main lobe be narrowed, if you wish to achieve more gain than you can get by simply redistibuting the rear-ward energy in the forward direction. This is what you alluded to before and it is still incorrect What "requires" what ? And how is this conclusion generating an elongated lobe? A super-high-gain antenna *cannot* have a wide, uniform beam-width in both azimuth and elevation. Don't know how you can say that I say that because the opposite case would contradict the law of conservation of energy. If you have an antenna which puts all of its power, uniformly, into a forward beam which covers only 1/10 of the sphere, then that forward beam will carry 10 times as much power per angle, for a gain of 10 dBi. If you squeeze the beam down in size so that it covers only 1/100 of the sphere, it will carry 100 times as much power per angle, for a gain of 20 dB. You can't have a broad forward lobe (say, one which covers a full 1/10 of the sphere), and achieve a high gain of 20 dB (100 times as much power per angle) without violating the law of conservation of energy. *THAT* is the fundamental limit I'm talking about, Art. As usual for your postings, Art, it's impossible to tell whether your claims for your antenna are plausible, because you refuse to disclose *anything* (either the invention, or the results you claim) in any halfway-tanglible form (e.g. models, specific numbers, etc.). My antenna is somewhat related You DID IT AGAIN, Art. You said "is somewhat related", you didn't say related to *what*, you didn't give any details whatsoever. The question however, is specifically related to Yagi's and its narrowed lobes. Do you know what it is that creats an elongated lobe on a high gain yagi i.e not totally round.? Nothing more, nothing less. You're acting as though the lobe were a physical object, and that something is "putting pressure" on it to squeeze it out of shape like a physical balloon. That is a FALSE ANALOGY, Art. It's meaningless. The "shape" of the lobe is simply a way of plotting numbers on a graph. It depends on the scaling of the graph, and it's a *relative* scale. A dipole's lobes may look perfectly round on one sort of graph, elliptical on another, and lumpy on a third, depending on whether the plot's axes are logarithmic, linear, or somewhere in between the two. Fundamentally, the reason that the shape of the lobe (on a conventional plot) changes from somewhat-circular to more-eliptical is due to the fact that the antenna is sending more of its power in a favored direction (to achieve gain), at the expense of sending less in other directions. Period. The *mechanism* by which this is done, in a Yagi (or an actively- driven set of phased radiators), is simply one of dividing up the power being radiated so that it's radiated (or re-radiated) from multiple points, in different spatial and phase relationships, so that the resulting waves cancel out in certain directions and reinforce in others. If you really want to know the details, I suggest that you dig up and read the original papers by Uda and Yagi. Until you do, I really think it would be to everyone's relief if you'd follow through with your recent statement that you were going to stop posting. You're achieving no good result for yourself by contining as you are. I have not posted as you have inferred. The question is about Yagi design It all seems to come down to the same thing with you, Art. I suppose I should just killfile you and completely ignore your postings. I'm sorry, I've tried my best to steer you in directions that I think will actually help your efforts, but it seems quite futile. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
" wrote:
The shape changes can come from squeezing the balloon (pattern) horizontally, vertically, or in combination -- which, in antenna hardware is accomplished by an appropriate array of, and feed system for, its radiating elements. Right..... so what creats it, this "squeezing" that you talk about and from where does this "squeezing force come from in an "appropiate"array? That's what I was asking not a discussion of what the Yagi array produces. Why does the lobe narrow? ______________ Narrowing is the natural result of the vector addition of the separate EM waves radiated from the individual sources comprising the Yagi (or any other kind of directional array). RF |
In article bkE1e.110371$Ze3.24514@attbi_s51,
wrote: Right..... so what creats it, this "squeezing" that you talk about and from where does this "squeezing force come from in an "appropiate"array? There is no "force" in the usual sense of pressure on a physical balloon. That's because the "balloon" is not an object. It's simply a mathematical abstraction - a drawing of lines of equal RF power levels on a graph having a certain set of axes. To think that there's a specific 'force' squeezing the 'balloon', is somewhat like trying to travel from east to west by pulling yourself along the lines of longitude. Hey, the lines are there on the globe, they're there on the map, why can't I just walk along the lines? There's nothing "pushing" on the "boundaries" of the lobe, because there is no lobe in the physical sense. It's not a separate and distinct object. To understand why there's a change in the shape that we visualize (and that's all that the lobe shape is - a selective visualization), we have to step down to the underlying phenomenon and see what's changing. Because the conventional "lobe shape" is simply the result of plotting the strength of the RF energy coming from the antenna, the answer is simple. The lobe's shape is changing, because the amount of RF energy being transmitted in the different directions is changing... .... and *that* happens because the phase-and-location details of the various radiators (and re-radiators) in the antenna system are being altered. Different radiator and re-radiator locations, intensities, and phases... .... cause different "sum of vectors" results ... .... which changes the strength of the RF received ... .... which, when we walk around and try to locate the points having equal RF field strength, means that we walk along different paths ... .... which means that we draw the lines on the map in different places ... .... which means that the "lobes" now have a different shape. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
"Dave Platt" wrote in message ... In article uoD1e.110018$Ze3.66917@attbi_s51, wrote: There is a harsh limit, imposed by physics, as to how much gain that approach can give you. Agreed... Do you know what those limits are ? Sure. The simplest way to state it is "the total amount of power delivered by the antenna, summed over all of the possible angles of radiation, must equal the total amount of power radiated by the antenna." If all of the energy from one hemisphere is redirected into the other hemisphere, and if the forward-direction pattern shape does not change (the forward lobe is not narrowed), then you have a forward gain of 3 dB But the forward pattern DOES change with a YAGI design. In fact it inferes unequal pressures within the pattern. I would have no problem with a lot of what you say BUT the YAGI does not follow the theoretical aproach that you supplied thus what you say regarding a yagi is based on a straw man augument. My question was for the Yagi pattern which does not follow your aproach You cannot relate gain and power since with a yagi tho power is an all encompasing term (three dimensional) gain is not. What you stated earlier regarding gain as a ratio is correct but for a Yagi its parameters must be defined which is not by the term power. as you have used it. (2:1 power ratio increase). You *cannot* have more, as this would require that the antenna be radiating more power than it receives from its input. Absolutely incorrect. If I place the air of two balloons ,which reflect the figure eight,into one single balloon and where the laws of partial pressures do not intervene then you will have a balloon that is round and not elongated as the antenna books would have you suggest. "Gain" is a term used to to quantify a small portion of the energy contained in the mythical ball of energy. Since the collection of energy comes from different directions and phases the energy collection is layered depending on the influence of the earth. Thus the layers of radiation are distorted where one layer can be squeezed outwards further than other layers, thus the terminology of "gain" Jeez, Art, do you have any idea of just how thoroughly your response qualifies as "Authentic frontier gibberish" (as a Mel Brooks character once said)? I'm sorry, guy, but I believe that you are trying to stretch analogies far beyond the point where they actually apply to the physical phenomena we're discussing. Your concept of "layers of radiation" (as applied to the gain pattern of an antenna) simply doesn't add up. If you are going to interelate the terms of "gain" and "power" then you must define the parameters used to allow that. OK, let's do just that. "Power" is very well defined - it's the rate at which energy is delivered. Pick your units for energy and time as you choose. It's conventional to use watts for power, joules for energy and seconds for time. One watt, equals a rate of energy delivery of one joule per second. "Gain" is a ratio. In discussions dealing with antennas, the gain describes the ratio between the amount of power delivered by a given antenna in a given direction, to the amount of power delivered in that same direction by a "reference" antenna (a dipole in the case of a dBd gain number, and an "isotropic" antenna in the case of a dBi gain number). The gain figures in dB are logarithmic. Those are the definitions everyone uses, I believe. I can go along with that If you, personally, are using different definitions than these, then our discussion (you vs. everyone else) should probably stop right here. Here's my rationale behind the statement I made about the limitations of your approach: - An isotropic antenna has a gain of 0 dBi, by definition. - If you "cut off" the entire rear side of an isotropic antenna's pattern (so that it radiates no power backwards), and precisely overlay this power (energy flow) onto the forward half, you'll end up with a "half-isospheric" antenna. It's radiating exactly the same amount of power, but over only half as much target area. The power (energy flow) towards each point in that targeted hemisphere will be exactly twice as much as in the isotropic antenna. This antenna has a gain of 3 dBi plus a hair. As you say, when you are refering to isentropic It cannot have *more* gain in any direction (more power into a sub-portion of the hemisphere) unless it has *less* gain in another portion of that hemisphere... For the isotropic aproach which has little relationship to the real world of yagis that some how narrows not only the main lobe but also the other lobes all of which have seperate gains created by the movement of energy from the rear and not constrained by your theoretical 3 db aproach in other words, unless is starts exhibiting some form of lobing/nulling. If it *could*, it would be trivial to demonstrate that the antenna was delivering more power (more energy over time) into its loads, than it was accepting from its transmitter. The same line of logic applies even if you start with a dipole. If you begin with a dipole, and then magically "deflect" all of the power from the rear towards the front and overlay the patterns exactly, you'll exactly double the power in each forward-lying half of the sphere, and create a gain of 3 dB over the dipole. In order to have *more* forward gain in any direction in the forward direction, you must necessarily have *less* in another, and this either narrows the pattern in the forward direction or creates partial or complete nulls. To claim otherwise, is to claim an antenna which can be shown to deliver more power than it accepts as input... in other words, one which violates the conservation of energy. The same basic rule applies for any situation in which you take a bidirectional antenna (one which has a symmetrical forward-and- backward gain pattern) and then "deflect" all of the rearward energy into a forward direction. This will gain you at most 3 dB over the basic gain pattern of the antenna you started with. Any further maximum forward gain, over the antenna you were starting with, can *only* be achieved by decreasing the gain somewhere in the pattern (narrowing or weakening the main lobe or one of the sidelobes). A Moxon antenna is, to a first approximation, a pretty good example of this approach - it has very little energy in the rear hemisphere, and a broad forward lobe. There are various two-driven-element array designs which achieve a similar pattern and result. And the resulting "gain" is ....what? According to Cebik's web site, a 2-meter Moxon shows a maximum forward gain of about 10.7 dBi, or a bit more than 8 dB over a dipole. One could gain at most 3 dB due to the forward "deflection" of rear- hemisphere energy, and hence the remaining 5 dB or so of gain over a dipole must come from a narrowing of the antenna's pattern in either azimuth or elevation or both. Yes I agree because of conservation laws e.t.c . When cancellation occurs then energy creats energy in another direction similar to pulling steel apart in tension (or using compression) the steel becomes narrower before severing occurrs. This thinning or "waisting" is created by the additional forces created at 90 degrees to the tensile forces and where the break actually occurrs at 45 degrees and not at right angles. Art, I think your analogies between radiation patterns, balloons, stretching metal, etc. are leading you astray more than they are helping you. Conservation of energy *requires* that the main lobe be narrowed, if you wish to achieve more gain than you can get by simply redistibuting the rear-ward energy in the forward direction. This is what you alluded to before and it is still incorrect What "requires" what ? And how is this conclusion generating an elongated lobe? A super-high-gain antenna *cannot* have a wide, uniform beam-width in both azimuth and elevation. Don't know how you can say that I say that because the opposite case would contradict the law of conservation of energy. If you have an antenna which puts all of its power, uniformly, into a forward beam which covers only 1/10 of the sphere, then that forward beam will carry 10 times as much power per angle, for a gain of 10 dBi. If you squeeze the beam down in size so that it covers only 1/100 of the sphere, it will carry 100 times as much power per angle, for a gain of 20 dB. You can't have a broad forward lobe (say, one which covers a full 1/10 of the sphere), and achieve a high gain of 20 dB (100 times as much power per angle) without violating the law of conservation of energy. *THAT* is the fundamental limit I'm talking about, Art. As usual for your postings, Art, it's impossible to tell whether your claims for your antenna are plausible, because you refuse to disclose *anything* (either the invention, or the results you claim) in any halfway-tanglible form (e.g. models, specific numbers, etc.). My antenna is somewhat related You DID IT AGAIN, Art. You said "is somewhat related", you didn't say related to *what*, you didn't give any details whatsoever. Oh come on Dave, don't twist things around. I have stated that my antenna, which is not a yagi, when transposing pattern volume from the rear to the front does it in an orderly fashion by expansion of the receiving vessel in a circular form. .. Thus the gain increased as the rear volume decreased with a diminishing increase in gain. The yagi does something different as other vectorial interferences is creating "outward pressures" on the so called balloon to NARROW the beam width. Disregarding any effects that can be attributed to other antennas my question is related to the YAGI design which actually creates a narrowing beam as progress is made in transposing energy from the front to the rear. This is a fact , thus the question "why" a question that is pertinent to the YAGI design and not any other design or multiple arrangements of such.. You have supplied plenty of dots regarding antennas but none that remotely relates to the question The question however, is specifically related to Yagi's and its narrowed lobes. Do you know what it is that creats an elongated lobe on a high gain yagi i.e not totally round.? Nothing more, nothing less. You're acting as though the lobe were a physical object, and that something is "putting pressure" on it to squeeze it out of shape like a physical balloon. That is a FALSE ANALOGY, Art. It's meaningless. The "shape" of the lobe is simply a way of plotting numbers on a graph. It depends on the scaling of the graph, and it's a *relative* scale. A dipole's lobes may look perfectly round on one sort of graph, elliptical on another, and lumpy on a third, depending on whether the plot's axes are logarithmic, linear, or somewhere in between the two. Fundamentally, the reason that the shape of the lobe (on a conventional plot) changes from somewhat-circular to more-eliptical is due to the fact that the antenna is sending more of its power in a favored direction (to achieve gain), at the expense of sending less in other directions. Period. The *mechanism* by which this is done, in a Yagi (or an actively- driven set of phased radiators), is simply one of dividing up the power being radiated so that it's radiated (or re-radiated) from multiple points, in different spatial and phase relationships, so that the resulting waves cancel out in certain directions and reinforce in others. If you really want to know the details, I suggest that you dig up and read the original papers by Uda and Yagi. Until you do, I really think it would be to everyone's relief if you'd follow through with your recent statement that you were going to stop posting. You're achieving no good result for yourself by contining as you are. I have not posted as you have inferred. The question is about Yagi design It all seems to come down to the same thing with you, Art. I suppose I should just killfile you and completely ignore your postings. I'm sorry, I've tried my best to steer you in directions that I think will actually help your efforts, but it seems quite futile. By all means put me on your kill file. I asked a simple question and you want to reply to a different question of your liking and place your question as one preferable to mine. No one has been able to supply the answer to my question, Using your words ,what steers the pattern away from a circular form from a natural circular form. I am not asking for the extraneious information that all feel they are compelled to supply to make their posting look informative. Regards Art -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Great! I would disagree with respect to "any other type of directional array
but I would like a further insight to the mechanics of vector array that produces this phenomina. I would like to reproduce this effect else where if I could. Regards Art "Richard Fry" wrote in message ... " wrote: The shape changes can come from squeezing the balloon (pattern) horizontally, vertically, or in combination -- which, in antenna hardware is accomplished by an appropriate array of, and feed system for, its radiating elements. Right..... so what creats it, this "squeezing" that you talk about and from where does this "squeezing force come from in an "appropiate"array? That's what I was asking not a discussion of what the Yagi array produces. Why does the lobe narrow? ______________ Narrowing is the natural result of the vector addition of the separate EM waves radiated from the individual sources comprising the Yagi (or any other kind of directional array). RF |
" wrote
Great! I would disagree with respect to "any other type of directional array' but I would like a further insight to the mechanics of vector array that produces this phenomina. I would like to reproduce this effect else where if I could. ___________ Suggest you get this background from a good read of just about any of the many antenna textbooks available. It's a bit much to deal with in a NG forum. RF |
Hal I think you are right
It is magic!. I think that this subject has been pushed to one side during the last century in the event anybody should come along and say all is known about antennas so we can put them in their place. Someday, someone will come along with an answer and then we can all jump on him and ask him to prove it so the monkey is not on our backs. The post did attract a lot of interest tho even if there was not a cigar supplied. It really is amazing what photons can do when they become all entangled. Time to get back to what SWR really entails when all can put their two pennies worth in. I've got to now draw a circle with a compass and observe how the shape changes when replotted with logrithmic and other types of graph paper Regards Art "Hal Rosser" wrote in message . .. "Cecil Moore" wrote in message ... wrote: So to the gurus of this group, what actualy creates the narrowing of the forward lobes ? The narrowing of the forward lobes is caused by constructive interference during superposition of EM waves. -- 73, Cecil http://www.qsl.net/w5dxp Darn - I thought it was pure magic. Now we hear all about induced currents and interference patterns cancelling in the rearward and the sides, but constructively interferring in the forward direction. All in an attempt to become the chosen guru of the original poster. If nominated, I will not run - if elected - I will not serve. |
I've got to now draw a circle with a compass and observe how the shape
changes when replotted with logrithmic and other types of graph paper Regards Art Be sure to give us a report on creating the logarithmic graph paper. If I heard someone was looking to replot circles on log graph paper, I would say he must be a ham. Then I would think about writing a Java program to do it, as I slipped into sleep while listening to 'Coast-to-coast-AM' on the radio. |
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In article P2G1e.110904$Ze3.11791@attbi_s51,
wrote: By all means put me on your kill file. I asked a simple question and you want to reply to a different question of your liking and place your question as one preferable to mine. Art, in cases like this, you keep asking "simple questions" which imply, by their very wording, a whole bunch of assumptions about how things work which just ain't so. The fact that you keep getting answer after answer, from a lot of knowledgeable people, which you either don't understand or "blow past" or that you feel evade the point of your question, ought to be saying something to you: that there's something wrong with the questions you ask. No one has been able to supply the answer to my question, Using your words ,what steers the pattern away from a circular form from a natural circular form. That depends on what you mean by "a natural circular form." If you're referring to the fact that the main lobe of a dipole tends to look circular on many of the commonly-used plots, then the pattern isn't "circular" in any cosmic sense of the word. It's just as correct to say that it's elliptical, or bumpy, or squashed, because that's exactly how it will look on plots which use different circular axes (linear, logarithmic, etc). To try it again, though: you're asking why the pattern appears to be compressed, as the gain increases. Fundamentally, it's due to the fact that the antenna is sending more power out in the desired directions (more gain), at the expense of sending less in other directions. This is done by creating multiple radiators, which are offset in power and location and phase so that their individual radiation wavefronts reinforce in the desired directions, and cancel in the undesired directions. When we plot the resulting RF strengths, the RF in the desired direction is stronger (we got the gain that we want). Let's assume that (as is common practice) we continue to plot the signal in the strongest direction on the outer circle of the graph. Now, one of two things will have to be true: [1] Every other direction in the main lobe had its power "scaled up" by the same amount... the increase in gain worked the same for all directions within the main lobe. In this case, the shape of the main lobe will not change at all. In this case, the additional power required to achieve the increase in gain in the main lobe will have had to come for somewhere. Since it didn't come from the main lobe, it will have had to come either from the sidelobes, or from the rear half of the antenna's pattern. There's a limit to how far you can take approach [1]. It stops working when your sidelobes and rear half of the pattern drop to zero... and it becomes rather ineffective some time before that, when the largest of the side/rear lobes is maybe 10-15 dB down. Beyond that point, there just isn't enough power left in those backlobes to be useful. [2] The other possibility is that you didn't manage to boost the gain, uniformly, in the entire main lobe. In this case, if you're still plotting the strongest signal on the outermost circle of the graph, you'll notice that the shape of the main lobe has changed. Any direction in which the gain increase was less than the maximum you achieved, will be closer to the center of the circle than before. [Another way of looking at this is that by increasing your maximum directional gain, you've "enlarged the circle" on which you're plotting it, but that some points didn't move outwards by the same ratio.] In the common case of a Yagi, when you boost the gain (say, from 10 dB to 15 dB) there just isn't enough power available in the side and rear lobes to make up this gain... you can't 'rob' enough directivity from the sidelobes and rear lobe. Instead, you 'rob' the power from the outer edges of the main lobe, and shift it in towards the center. You do this, most commonly, by adding additional parasitic elements, whose location and phasing are such that their radiation reinforces that moving in the "forward" direction, and interacts destructively with (cancels) radiation moving outwards at an angle. When you plot the resulting pattern, and scale it so that the strongest signal is on the outer circle of the plot, you find that the main lobe looks narrower. Part of this is due to the actual redirection of power, and part of it is due to the fact that you've re-scaled the graph.a .. I am not asking for the extraneious information that all feel they are compelled to supply to make their posting look informative. [invokes several wrathful deities...] Art, if you continue to ask "simple questions", and you continue to get back complicated and detailed answers, it really ought to convey to you the possibility that your "simple" question is oversimplified. Or, perhaps, that you've been given the actual (simple) answer three or four or five times already, have rejected it, and people are trying to explain to you why it's actually correct. Goodbye, Art. This is/was my last attempt, I think. I doubt I'll try again. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Hal
Amateur radio operators have been convinced to display radiation patterns on logarithmic paper to make it look more directional than normal plotting procedure. Since I can now generate a complete circle for an non yagi antenna array using logarithmic paper on my antenna program I thought it would be interesting to see what a circle would look like when using 'standard' graph paper.( a reverse procedure) Now, as I write this, I realise that my antenna computor program has the ability to make this transition. This will be interesting as I have no pre-expectations as to what it will show. Best regards Art "Hal Rosser" wrote in message . .. I've got to now draw a circle with a compass and observe how the shape changes when replotted with logrithmic and other types of graph paper Regards Art Be sure to give us a report on creating the logarithmic graph paper. If I heard someone was looking to replot circles on log graph paper, I would say he must be a ham. Then I would think about writing a Java program to do it, as I slipped into sleep while listening to 'Coast-to-coast-AM' on the radio. |
On Sun, 27 Mar 2005 19:53:44 GMT, "
wrote: No one has come up with a explanation Hi Art, As usual, I see you simply enjoy posting without corresponding. C'mon, it is more than obvious you have no interest in any explanation other than your own. Roy and a couple of others qualify and have yet to respond You've spit on them so much that is hardly surprising - is it? 73's Richard Clark, KB7QHC |
"Dave Platt" wrote in message ... In article P2G1e.110904$Ze3.11791@attbi_s51, wrote: By all means put me on your kill file. I asked a simple question and you want to reply to a different question of your liking and place your question as one preferable to mine. Art, in cases like this, you keep asking "simple questions" which imply, by their very wording, a whole bunch of assumptions about how things work which just ain't so. The fact that you keep getting answer after answer, from a lot of knowledgeable people, which you either don't understand or "blow past" or that you feel evade the point of your question, ought to be saying something to you: that there's something wrong with the questions you ask. No one has been able to supply the answer to my question, Using your words ,what steers the pattern away from a circular form from a natural circular form. That depends on what you mean by "a natural circular form." If you're referring to the fact that the main lobe of a dipole tends to look circular on many of the commonly-used plots, then the pattern isn't "circular" in any cosmic sense of the word. It's just as correct to say that it's elliptical, or bumpy, or squashed, because that's exactly how it will look on plots which use different circular axes (linear, logarithmic, etc). To try it again, though: I thank you for that you're asking why the pattern appears to be compressed, as the gain increases. Fundamentally, it's due to the fact that the antenna is sending more power out in the desired directions (more gain), at the expense of sending less in other directions. Fully agreed to This is done by creating multiple radiators, which are offset in power and location and phase so that their individual radiation wavefronts reinforce in the desired directions, and cancel in the undesired directions. Accepted as long as you can agree that a similar vector analysis with multiple radiators can also create a non focussing pattern When we plot the resulting RF strengths, the RF in the desired direction is stronger (we got the gain that we want). Let's assume that (as is common practice) we continue to plot the signal in the strongest direction on the outer circle of the graph. Now, one of two things will have to be true: [1] Every other direction in the main lobe had its power "scaled up" by the same amount... the increase in gain worked the same for all directions within the main lobe. In this case, the shape of the main lobe will not change at all. O.K. this would /could be the case I am thinking of In this case, the additional power required to achieve the increase in gain in the main lobe will have had to come for somewhere. Agreed Since it didn't come from the main lobe, it will have had to come either from the sidelobes, or from the rear half of the antenna's pattern. Agreed for over all gain but not necessarilly for the lobe becomming focussed which is the crux of my question There's a limit to how far you can take approach [1]. It stops working when your sidelobes and rear half of the pattern drop to zero... and it becomes rather ineffective some time before that, when the largest of the side/rear lobes is maybe 10-15 dB down. Beyond that point, there just isn't enough power left in those backlobes to be useful. Using a antenna computor program the main lobe at 10 degrees does not deviate from a circle even if the F/R is more than 30 db ( note F/R vs F/B) and this is comprised of vector addition mode as with a yagi design. [2] The other possibility is that you didn't manage to boost the gain, uniformly, in the entire main lobe. Hum! In this case, if you're still plotting the strongest signal on the outermost circle of the graph, you'll notice that the shape of the main lobe has changed. No, not always, only with a yagi design in my opinion Any direction in which the gain increase was less than the maximum you achieved, will be closer to the center of the circle than before. [Another way of looking at this is that by increasing your maximum directional gain, you've "enlarged the circle" on which you're plotting it, but that some points didn't move outwards by the same ratio.] Agreed thus my question In the common case of a Yagi, when you boost the gain (say, from 10 dB to 15 dB) there just isn't enough power available in the side and rear lobes to make up this gain... you can't 'rob' enough directivity from the sidelobes and rear lobe. Instead, you 'rob' the power from the outer edges of the main lobe, and shift it in towards the center. Now we are getting closer to my quest. How do we "rob" from the outer edge of the main lobe is the underpinnings of my question. You do this, most commonly, by adding additional parasitic elements, whose location and phasing are such that their radiation reinforces that moving in the "forward" direction, and interacts destructively with (cancels) radiation moving outwards at an angle. Agreed if we are adding or subtracting on a constant plane. Could you by any chance referring to the closing vector of the vector analysis to consist of two vectors and where one of these vectors is the force at right angles to the main lobe and which deforms it. If so I am beginning to see the light! When you plot the resulting pattern, and scale it so that the strongest signal is on the outer circle of the plot, you find that the main lobe looks narrower. Part of this is due to the actual redirection of power, and part of it is due to the fact that you've re-scaled the graph.a I am lost here but if we agree on my interpretation of what you said then I am at a point where I can generate vector diagrams of different arrays and forecast the width of the resultant lobe .Does anybody else agree that the main lobe width can be forecast via vector analysis. Seems like from past posts that vector analysis is not now in vogue for electrical engineers in the U,S and only creates blank stares when mentioned/ .. kes several wrathful deities...] Art, if you continue to ask "simple questions", and you continue to get back complicated and detailed answers, it really ought to convey to you the possibility that your "simple" question is oversimplified. Or, perhaps, that you've been given the actual (simple) answer three or four or five times already, have rejected it, and people are trying to explain to you why it's actually correct. Goodbye, Art. This is/was my last attempt, I think. I doubt I'll try again. But David, nobody pointed to vector analysis and the particular facet that you referred to. You are to be congratulated in pointing to a trail of logic that could well be the direction I was looking for. Nobody but you presented in real terms an analysis that leads to serious consideration and I thank you very much for that. Best regards Art KB9MZ.....xg g the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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Not so. If I cannot accept an answer that I figure to be unreasonable then I
do not accept them. In Roy's case I accept the majority of his explanations, but not all. In your case you come up with many knoweledgable explanations on various facets of science ,but in general, you concentrate more in attacking others opinions with out supplying corrections I say this only where your posts are clear and not smattered with relatively unused words where a shorter one would suffice How ever those are in the minority. If I do not concurr with any explanation offerred .in no way does this suggest that I am spitting on the individual and thus treating him with disrespect. In your case you treat me in disrespect which as far as I am concerned requires reciprical treatment. You ask for it and you will get it from me without retreat On the other hand respect demands respect, your choice as I am now americanised for retaliation without regard to common courtesy as per the Britts Art "Richard Clark" wrote in message ... On Sun, 27 Mar 2005 19:53:44 GMT, " wrote: No one has come up with a explanation Hi Art, As usual, I see you simply enjoy posting without corresponding. C'mon, it is more than obvious you have no interest in any explanation other than your own. Roy and a couple of others qualify and have yet to respond You've spit on them so much that is hardly surprising - is it? 73's Richard Clark, KB7QHC |
Using a antenna computor program the main lobe at 10 degrees does
not deviate from a circle even if the F/R is more than 30 db ( note F/R vs F/B) and this is comprised of vector addition mode as with a yagi design. ================================= Using a computer program automatically incorporates all the defects in the programmer's reasoning and understanding of the problems involved - plus other bugs. Never use a computer program as the Bible. |
Tom, now you are being silly.
You obviously do not know all about antennas other wise you would be anxious to display your knoweledge as to why this is impossible. But then you can't and thus want to assault the messenger. I could present the facts to an individual for confirmation but this would only mean a deflection of comments from me to the adjudicator from people with the pre disposition of yourself Art "Tom Ring" wrote in message .. . wrote: You are not alone as I thought it meant quieter contacts but it is said (ARRL publication) that it then becomes more difficult to aim, ala the rombic. That's why I see my antenna's flattening of the main lobe without loss in beam width an advantage. Oh boy, is this going to be fun! Next he'll be selling a box that does perpetual motion. tom K0TAR |
I could not agree more This is why I requested comment on my computor
findings. It is easy to generate a program to agree with what is known to all. It is another thing to pre forecast results from an untried array. It appears from comments given that the computor programs are not to be fully accepted, especially if a lobe pattern produced is circular in nature and of various thickness Tho I must admit I am unaware of what text books they are being guided from. , Regards Art "Reg Edwards" wrote in message ... Using a antenna computor program the main lobe at 10 degrees does not deviate from a circle even if the F/R is more than 30 db ( note F/R vs F/B) and this is comprised of vector addition mode as with a yagi design. ================================= Using a computer program automatically incorporates all the defects in the programmer's reasoning and understanding of the problems involved - plus other bugs. Never use a computer program as the Bible. |
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"Tom Ring" wrote in message .. . wrote: Tom, now you are being silly. You obviously do not know all about antennas other wise you would be anxious to display your knoweledge as to why this is impossible. But then you can't and thus want to assault the messenger. I could present the facts to an individual for confirmation but this would only mean a deflection of comments from me to the adjudicator from people with the pre disposition of yourself Art Nope, I don't know everything, but I do know the amount of energy radiated can't be more than what the transmitter outputs, so the sum of energy around the sphere has to equal that. Goodness me, do you really think that is in quesdtion in this debate ? If you think you can make the main lobe broader, then you are implying that you can radiate more powwr than than was originally there. You really are jumping the Grand Canyon in TWO strides !. I have no idea what you are saying or alluding to. To make something broarder is describing one dimension only.. less if used in ratio terms To describe energy one must have more than one dimension or unit. Surely one must know this to graduate from High school in the U.S. or am I mistaken.? If so it then accounts for some of the wierd responses that have come my way. Art tom K0TAR |
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snip
" wrote in message news:h7L1e.388$Vx1.382@attbi_s01... "Tom Ring" wrote in message .. . wrote: snip Art Your statement Nope, I don't know everything, but I do know the amount of energy radiated can't be more than what the transmitter outputs, so the sum of energy around the sphere has to equal that. My response Goodness me, do you really think that is in quesdtion in this debate ? Your statement If you think you can make the main lobe broader, then you are implying that you can radiate more powwr than than was originally there. My response You really are jumping the Grand Canyon in TWO strides !. I have no idea what you are saying or alluding to. To make something broarder is describing one dimension only.. less if used in ratio terms To describe energy one must have more than one dimension or unit. Surely one must know this to graduate from High school in the U.S. or am I mistaken.? If so it then accounts for some of the wierd responses that have come my way. Art QED Art tom K0TAR |
On Mon, 28 Mar 2005 02:40:38 GMT, "
wrote: If I cannot accept an answer that I figure to be unreasonable then I do not accept them. Hi Art, This is your standard line of bull****. Don't blame Shakespeare for this standard offering of anglo-saxon clarity. The simple answer to your question was already revealed in your question which offered in part: is formed using Yagi principles. Nothing more, nothing less. Exactly. I know this may come as a shock to you, but the obvious problem is that you have absolutely no understanding of just what Yagi principles. means and you refuse to go there. If you want to make this a 12 step Shakespearian comedy, keep ignoring the elephant in your living room. 73's Richard Clark, KB7QHC |
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