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Yagi efficiency
Some time ago I mentioned how inefficient Yagi design
antennas were thinking more in the way of how little of the radiation used got to its required direction. At that time people said the antenna was efficient though they wanted to talk about actual radiation efficiency and the sniping began ..Nobody but nobody came back with the radiation efficiency of a Yagi as they saw the question, they just wanted to throw stones.Imagine that antennas was not what the experts wanted to talk about and the newsgroup took a turn for the worst So I join in with the thoughts of radiation efficiency of a yagi unless you prefere to give up this antenna newsgroup. But before you scream out and throw stones again I will referr to efficiency as most of the members of this group what's left of them think of the term. So let's look at that if that is what you preferr.. The basic small yagi has three elements one driven, one a reflector and one a director yet only one element has a truly resistive impedance whereas the other two do not. Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? And please, please don't waste time on "I don't understand" otherwise everything drops down to the subject of spark noise which was really decided by hams a long while ago. On the other side of the coin, if the reactive portion of an impedance is not waste then why is LCR type mesh circuitry only revolve around lumped circuitry? HINT add up the power emminating from each element P =I sq times real resistance for those who are just followers. There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! |
Yagi efficiency
art wrote:
snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR |
Yagi efficiency
art wrote:
There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Interesting, but you cannot argue with decibels, and the yagi is more efficient that a dipole without reflector and director, at least at capturing signal. However, while I can picture the reflector acting as a mirror (and to some extent, this can be "proven", make the reflector a sheet and see how much signal is radiated to the other side, away from the driven element. But, that darn director has always bothered me, I see it acting more as a "magnifying glass to rf" than absorbing the signal and re-radiating it to the de, or absorbing the signal and coupling it to the de via magnetic or capactive means... one more bit of a puzzle which gives me visions of the ether (which some say is caused by evil spirits and/or the drugs I did in college (I don't think the beer hurt anything!)) But, with his calculator in hand, I know cecil will take this head on... JS |
Yagi efficiency
Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. |
Yagi efficiency
art wrote:
Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. Actually Art, you never listen to reasonable arguments, so I didn't offer one. tom K0TAR |
Yagi efficiency
art wrote:
Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
"art" wrote in message ups.com... Some time ago I mentioned how inefficient Yagi design antennas were thinking more in the way of how little of the radiation used got to its required direction. At that time people said the antenna was efficient though they wanted to talk about actual radiation efficiency and the sniping began .Nobody but nobody came back with the radiation efficiency of a Yagi as they saw the question, they just wanted to throw stones.Imagine that antennas was not what the experts wanted to talk about and the newsgroup took a turn for the worst So I join in with the thoughts of radiation efficiency of a yagi unless you prefere to give up this antenna newsgroup. But before you scream out and throw stones again I will referr to efficiency as most of the members of this group what's left of them think of the term. So let's look at that if that is what you preferr.. The basic small yagi has three elements one driven, one a reflector and one a director yet only one element has a truly resistive impedance whereas the other two do not. Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? And please, please don't waste time on "I don't understand" otherwise everything drops down to the subject of spark noise which was really decided by hams a long while ago. On the other side of the coin, if the reactive portion of an impedance is not waste then why is LCR type mesh circuitry only revolve around lumped circuitry? HINT add up the power emminating from each element P =I sq times real resistance for those who are just followers. There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Hi Art OK, I dont understand. Perhaps I could begin to understand if I was given the definition of efficiency we are using in this discussion. How do you define efficiency? Jerry |
Yagi efficiency
art wrote:
See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And, actually Art, and most important, you seem to have no comprehension about what is possible to realize with a yagi that is about a half wavelength. What you want to do takes yagis that are 10, 20 or more wavelengths. And very high above the ground. Reality is a nasty thing. tom K0TAR |
Yagi efficiency
John Smith wrote: art wrote: There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Interesting, but you cannot argue with decibels, and the yagi is more efficient that a dipole without reflector and director, at least at capturing signal. So the increase in reactive impedances radiation efficiency goes up? However, while I can picture the reflector acting as a mirror (and to some extent, this can be "proven", make the reflector a sheet and see how much signal is radiated to the other side, away from the driven element.hat energy d it Oh come on John, Llewellyn states the rear adds to forward radiation and you come along with similar junk. A vector to the rear where there is an detuned element which some how over turns the idea of energy can't be created or destroyed ? I suppose Roy will come up with some trash that because the reflector is reactive it overcomes the vector that created it! But, that darn director has always bothered me, I see it acting more as a "magnifying glass to rf" than absorbing the signal and re-radiating it Come on John if it is detuned from the frequency of use it can;'t be reradiating everything remember the hint I gave in the posting to the de, or absorbing the signal and coupling it to the de via magnetic or capactive means... Oh John you have done it again if you are going to revolve your position around coupling then losses will mount up even more. It really isnt a puzzle unless you listen to comments from experts who only read about Yagi's and shut everything else out or are just looking for an opportunity to snipe or emmulate snow code. one more bit of a puzzle which gives me visions of the ether (which some say is caused by evil spirits and/or the drugs I did in college (I don't think the beer hurt anything!)) But, with his calculator in hand, I know cecil will take this head on... I thought ether was something that did not posses its own energy support only a mediam for energy to pass thru, but we could change the subject to that I suppose JS |
Yagi efficiency
John Smith wrote: art wrote: There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Interesting, but you cannot argue with decibels, and the yagi is more efficient that a dipole without reflector and director, at least at capturing signal. So the increase in reactive impedances radiation efficiency goes up? However, while I can picture the reflector acting as a mirror (and to some extent, this can be "proven", make the reflector a sheet and see how much signal is radiated to the other side, away from the driven element.hat energy d it Oh come on John, Llewellyn states the rear adds to forward radiation and you come along with similar junk. A vector to the rear where there is an detuned element which some how over turns the idea of energy can't be created or destroyed ? I suppose Roy will come up with some trash that because the reflector is reactive it overcomes the vector that created it! But, that darn director has always bothered me, I see it acting more as a "magnifying glass to rf" than absorbing the signal and re-radiating it Come on John if it is detuned from the frequency of use it can;'t be reradiating everything remember the hint I gave in the posting to the de, or absorbing the signal and coupling it to the de via magnetic or capactive means... Oh John you have done it again if you are going to revolve your position around coupling then losses will mount up even more. It really isnt a puzzle unless you listen to comments from experts who only read about Yagi's and shut everything else out or are just looking for an opportunity to snipe or emmulate snow code. one more bit of a puzzle which gives me visions of the ether (which some say is caused by evil spirits and/or the drugs I did in college (I don't think the beer hurt anything!)) But, with his calculator in hand, I know cecil will take this head on... I thought ether was something that did not posses its own energy support only a mediam for energy to pass thru, but we could change the subject to that I suppose JS |
Yagi efficiency
Could be, seems reasonable but some want to view the yagi as the cats
wiskers and totally efficient which it cannot be despite all the trash talk from so called experts Tom Ring wrote: art wrote: Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
Could be, seems reasonable but some want to view the yagi as the cats
wiskers and totally efficient which it cannot be despite all the trash talk from so called experts Tom Ring wrote: art wrote: Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
Not a reasonable answer, could be speculation like some of the comments
I get from experts. The yagi is not totally efficient in changing the time changing field to a radiative field because it has detuned elements contrary to what Roy states that a reflector aids the forward lobe.......that is trash talk but many of the so called experts are following like lemmons Tom Ring wrote: art wrote: Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
Not a reasonable answer, could be speculation like some of the comments
I get from experts. The yagi is not totally efficient in changing the time changing field to a radiative field because it has detuned elements contrary to what Roy states that a reflector aids the forward lobe.......that is trash talk but many of the so called experts are following like lemmons Tom Ring wrote: art wrote: Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
art wrote:
Not a reasonable answer, could be speculation like some of the comments I get from experts. The yagi is not totally efficient in changing the time changing field to a radiative field because it has detuned elements contrary to what Roy states that a reflector aids the forward lobe.......that is trash talk but many of the so called experts are following like lemmons So why is it then, that Roy and several dozen others here have made good livings, written respected books, and designed antenna systems that defined how good it can get? And all you have done is call them names? Sounds like the "so called experts" are a lot effing smarter than you. All you have done is throw stones, which is what you accuse all of us of, by the way. And you haven't given a microgram of proof that what you believe is true. tom K0TAR |
Yagi efficiency
Hi Jerry perhaps I am wrong that there ARE people who want to talk
antennas We went thru this some time ago and I was referring to efficiency of the yagi antenna with respect to the radiation field where much is reflected to areas of no concern. Others did not like this and said efficiency referred to is one of the radiation facets of a radiating array and the yagi is efficient and then the sniping statrted and the newsgroup went down hill as others joined to emulate and perpetuate abrasive non antenna related subjects. I just popped back to see if the group wanted to change back to antenna talk and posted the term efficiency of the yagi in terms of radiation which everybody was auguing about. Well things haven't changed they still just want to throw stones and more will join in as the thread goes on., Ill stick it out for an hour or so and then move on again. Cant wait for somebody to compare with free space stuff to add to the confusion, I know it will come Jerry Martes wrote: "art" wrote in message ups.com... Some time ago I mentioned how inefficient Yagi design antennas were thinking more in the way of how little of the radiation used got to its required direction. At that time people said the antenna was efficient though they wanted to talk about actual radiation efficiency and the sniping began .Nobody but nobody came back with the radiation efficiency of a Yagi as they saw the question, they just wanted to throw stones.Imagine that antennas was not what the experts wanted to talk about and the newsgroup took a turn for the worst So I join in with the thoughts of radiation efficiency of a yagi unless you prefere to give up this antenna newsgroup. But before you scream out and throw stones again I will referr to efficiency as most of the members of this group what's left of them think of the term. So let's look at that if that is what you preferr.. The basic small yagi has three elements one driven, one a reflector and one a director yet only one element has a truly resistive impedance whereas the other two do not. Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? And please, please don't waste time on "I don't understand" otherwise everything drops down to the subject of spark noise which was really decided by hams a long while ago. On the other side of the coin, if the reactive portion of an impedance is not waste then why is LCR type mesh circuitry only revolve around lumped circuitry? HINT add up the power emminating from each element P =I sq times real resistance for those who are just followers. There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Hi Art OK, I dont understand. Perhaps I could begin to understand if I was given the definition of efficiency we are using in this discussion. How do you define efficiency? Jerry |
Yagi efficiency
There you go Tom still giving comments but no substance. Pretty simple
accept that a yagi is not the best thing since sliced bread starting with the use of detuned elements. If you do not understand what detuning elements do then you can have nothing reasonable to offer so don't blame me for that. If you have a salient staement I'll listen because I started the thread. If you want to change things then start your own thread to get them talking about it. Boy.....posts are coming out of the woodwork, where has everybody been? Tom Ring wrote: art wrote: See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And, actually Art, and most important, you seem to have no comprehension about what is possible to realize with a yagi that is about a half wavelength. What you want to do takes yagis that are 10, 20 or more wavelengths. And very high above the ground. Reality is a nasty thing. tom K0TAR |
Yagi efficiency
Tom if you want to align yourself who say they don't understand that is
fine with me. Do you have anything to say about radiation efficiency of a yagi which is what the posting is about you mentioned something about 95 efficient which you got from some where you could describe why and how 5% of the input anergy is lost or were you just guessing? Start a new thread if you like and I will go to bed as I am going nowhere with this and I am not anxious to stay when profanitys break out and it is heading that way art wrote: Not a reasonable answer, could be speculation like some of the comments I get from experts. The yagi is not totally efficient in changing the time changing field to a radiative field because it has detuned elements contrary to what Roy states that a reflector aids the forward lobe.......that is trash talk but many of the so called experts are following like lemmons Tom Ring wrote: art wrote: Tom Ring wrote: art wrote: snip There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Actually Art, you are already the master of misunderstanding. tom K0TAR See Tom you had nothing of value to say about antennas or the question at hand I think you would be better conversing with members of this group who are intent on disruption and stop questions on antennas. What goes around comes around so I will not answer in kind. If you want to stick with the idea that a yagi is the next thing to sliced bread then be my guest Better still study up on the code so you can join friends. And to continue the theme - Actually Art, yagis are usually better than 95% efficient. tom K0TAR |
Yagi efficiency
ORIGINAL MESSAGE:
On 1 Dec 2006 18:29:51 -0800, "art" wrote: Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? ------------ REPLY FOLLOWS ------------ Please let us know what electronics school you attended so we can avoid it like the plague and, if at all possible, have it de-certified. Thanks, Bill, W6WRT |
Yagi efficiency
art wrote:
the so called experts are following like lemmons Kind of reminds ya of a defective cars. Huh? JS |
Yagi efficiency
Bill prove me wrong thats all you have to do prove me wrong
Its a simple statement detuned elements create inefficiency Avoid it like a plague you say, it is to late in your life to think about getting an education You have presented nothing of value to the question, absolutely nothing. I suggest you continue to be a lemming and follow the others. Doesnt it worry you that you have placed yourself out on a limb by preceeding experts comments instead of waiting so you can follow ? Seems like the antenna group is still happy with their fellow associates in the group so pick up some more stones say some swear words and impress the others. See you maybe in a couple of weeks when I may drop back in. so save some of those projectiles! Bill Turner wrote: ORIGINAL MESSAGE: On 1 Dec 2006 18:29:51 -0800, "art" wrote: Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? ------------ REPLY FOLLOWS ------------ Please let us know what electronics school you attended so we can avoid it like the plague and, if at all possible, have it de-certified. Thanks, Bill, W6WRT |
Yagi efficiency
Hi Art
You know, I am really a slow learner. I still dont understand how efficiency is defined. Can you try again to teach me how efficiency is defined?? Thanks Jerry "art" wrote in message ups.com... Hi Jerry perhaps I am wrong that there ARE people who want to talk antennas We went thru this some time ago and I was referring to efficiency of the yagi antenna with respect to the radiation field where much is reflected to areas of no concern. Others did not like this and said efficiency referred to is one of the radiation facets of a radiating array and the yagi is efficient and then the sniping statrted and the newsgroup went down hill as others joined to emulate and perpetuate abrasive non antenna related subjects. I just popped back to see if the group wanted to change back to antenna talk and posted the term efficiency of the yagi in terms of radiation which everybody was auguing about. Well things haven't changed they still just want to throw stones and more will join in as the thread goes on., Ill stick it out for an hour or so and then move on again. Cant wait for somebody to compare with free space stuff to add to the confusion, I know it will come Jerry Martes wrote: "art" wrote in message ups.com... Some time ago I mentioned how inefficient Yagi design antennas were thinking more in the way of how little of the radiation used got to its required direction. At that time people said the antenna was efficient though they wanted to talk about actual radiation efficiency and the sniping began .Nobody but nobody came back with the radiation efficiency of a Yagi as they saw the question, they just wanted to throw stones.Imagine that antennas was not what the experts wanted to talk about and the newsgroup took a turn for the worst So I join in with the thoughts of radiation efficiency of a yagi unless you prefere to give up this antenna newsgroup. But before you scream out and throw stones again I will referr to efficiency as most of the members of this group what's left of them think of the term. So let's look at that if that is what you preferr.. The basic small yagi has three elements one driven, one a reflector and one a director yet only one element has a truly resistive impedance whereas the other two do not. Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? And please, please don't waste time on "I don't understand" otherwise everything drops down to the subject of spark noise which was really decided by hams a long while ago. On the other side of the coin, if the reactive portion of an impedance is not waste then why is LCR type mesh circuitry only revolve around lumped circuitry? HINT add up the power emminating from each element P =I sq times real resistance for those who are just followers. There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Hi Art OK, I dont understand. Perhaps I could begin to understand if I was given the definition of efficiency we are using in this discussion. How do you define efficiency? Jerry |
Yagi efficiency
Jerry Martes wrote:
... How do you define efficiency? Jerry Jerry: You make that sound like such a simple question. Antenna efficiency is a complicated and often misused figure. All antennas suffer from losses. A simple horn antenna for example will not be as efficient as a perfect aperture of the same size because of phase offset. The real efficiency of an antenna combines impedance match with other factors such as aperture and radiation efficiency to give the overall radiated signal for a given input. The best and mostwidely used expression of this efficiency is to combine overall efficiency with directivity (of the antenna) and express the efficiency times directivity as gain. The above is NOT mine, but taken from the web... http://www.tmcdesign.com/antenna%20c...nformation.htm So, we need to know if we are discussing antenna efficiency, or radiation efficiency, or the skin effect as related to the ether efficiency, etc. grin Good that you are asking him! Regards, JS |
Yagi efficiency
"John Smith" wrote in message ... Jerry Martes wrote: ... How do you define efficiency? Jerry Jerry: You make that sound like such a simple question. Antenna efficiency is a complicated and often misused figure. All antennas suffer from losses. A simple horn antenna for example will not be as efficient as a perfect aperture of the same size because of phase offset. The real efficiency of an antenna combines impedance match with other factors such as aperture and radiation efficiency to give the overall radiated signal for a given input. The best and mostwidely used expression of this efficiency is to combine overall efficiency with directivity (of the antenna) and express the efficiency times directivity as gain. The above is NOT mine, but taken from the web... http://www.tmcdesign.com/antenna%20c...nformation.htm So, we need to know if we are discussing antenna efficiency, or radiation efficiency, or the skin effect as related to the ether efficiency, etc. grin Good that you are asking him! Regards, JS Hi John It really *is* a simple question. Again, how is Efficienct being defined for this investigation?? As you have written, that question has to be answered by Art, the original poster, ?doesnt it? I was a little embarrassed because that "definition" of gain in the referenced site was really difficult for me to understand. I really admire you guys who understand phrases like "phase offset" as related to efficiency. Jerry |
Yagi efficiency
"art" wrote in message
Some time ago I mentioned how inefficient Yagi design antennas were thinking more in the way of how little of the radiation used got to its required direction. etc _________________ The above statement does not agree with the measured patterns and performance results of Yagi antennas. A well-designed, 6-element Yagi has a peak gain of at least 10 dBi, which means that it radiates about 6.3 times more power in that direction than if the same input power was radiated by a reference 1/2-wave dipole, and measured in its direction of maximum gain. RF |
Yagi efficiency
For those who wish to actually learn and not just insult each other,
get a calculator, learn how to calculate Cosine Theta a trivial math problem that any 9th grader can be taught in 5 minutes flat, get a BIG piece of paper reason to come, and actually calculate the shape and vector length of the lobes of a two element Yagi-Uda antenna... Do the calculation in both the horizonal and vertical planes... From that you can calculate the volume of each lobe, which is proportional to the percentage of power in each lobe... From that number you can very simply calculate what percentage went into the lobes you prefer and what went in the lobes you don't prefer... Now, the reason for the BIG piece of paper... The antenna patterns you see on the screen with EZNEC, or in the antenna handbooks, are logarithmic, not linear and there are flavors to them, ARRL, linear logarithmic, modified logarithmic... So, the patterns are distorted... Why is that? Because if they were linear and the front lobe and the rear lobe are to the same scale the front lobe will take up the entire length of the screen/paper and the rear lobe will need a magnifying glass to be seen... A rear lobe that is 20dB down from the front lobe is down by the power ratio of 100... So, if your forward lobe calculates out to be 10 inches long, the rear lobe will be be 1/10 of an inch.... I'll let you figure out the size of a lobe that is 30dB down (get out your microscope) For those who want to review do a search on Joseph Reisert, who has published numerous writings on antennas and patterns... There many are others also, but Joe is published on the web, and very readable... cheers ... denny / k8do |
Yagi efficiency
"Denny" wrote in message oups.com... For those who wish to actually learn and not just insult each other, get a calculator, learn how to calculate Cosine Theta a trivial math problem that any 9th grader can be taught in 5 minutes flat, get a BIG piece of paper reason to come, and actually calculate the shape and vector length of the lobes of a two element Yagi-Uda antenna... Do the calculation in both the horizonal and vertical planes... From that you can calculate the volume of each lobe, which is proportional to the percentage of power in each lobe... From that number you can very simply calculate what percentage went into the lobes you prefer and what went in the lobes you don't prefer... Now, the reason for the BIG piece of paper... The antenna patterns you see on the screen with EZNEC, or in the antenna handbooks, are logarithmic, not linear and there are flavors to them, ARRL, linear logarithmic, modified logarithmic... So, the patterns are distorted... Why is that? Because if they were linear and the front lobe and the rear lobe are to the same scale the front lobe will take up the entire length of the screen/paper and the rear lobe will need a magnifying glass to be seen... A rear lobe that is 20dB down from the front lobe is down by the power ratio of 100... So, if your forward lobe calculates out to be 10 inches long, the rear lobe will be be 1/10 of an inch.... I'll let you figure out the size of a lobe that is 30dB down (get out your microscope) For those who want to review do a search on Joseph Reisert, who has published numerous writings on antennas and patterns... There many are others also, but Joe is published on the web, and very readable... cheers ... denny / k8do Hi Denny Does Joseph Reisert define Efficiency as applied to this question about Yagi antennas? Jerry |
Yagi efficiency
"art" wrote in message oups.com... There you go Tom still giving comments but no substance. Pretty simple accept that a yagi is not the best thing since sliced bread starting with the use of detuned elements. If you do not understand what detuning elements do then you can have nothing reasonable to offer so don't blame me for that. If you have a ok, so educate us, what do detuned elements do? |
Yagi efficiency
art wrote:
Its a simple statement detuned elements create inefficiency Do detuned elements increase I^2*R losses? Do detuned elements increase dielectric losses? Do detuned elements increase ground losses? -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
Jerry Martes wrote:
Can you try again to teach me how efficiency is defined?? What kind of efficiency? antenna? beam? aperture? overall? conduction-dielectric? Balanis defines overall antenna efficiency as the product of: 1. reflection (mismatch) efficiency 2. conduction efficiency 3. dielectric efficiency He gives the conduction-dielectric efficiency as: Rr/(RL + Rr) where Rr is the radiation resistance and RL is the (conduction + dielectric) losses He gives beam efficiency as: (Beam cone power)/(Total radiated power) He also says for a 1-dimensional aperture as a function of taper: "The aperture efficiency is a maximum with no taper, while the beam efficiency is a maximum with full taper." -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
ORIGINAL MESSAGE:
On 2 Dec 2006 05:36:05 -0800, "Denny" wrote: For those who wish to actually learn and not just insult each other, get a calculator, learn how to calculate Cosine Theta a trivial math problem that any 9th grader can be taught in 5 minutes flat, get a BIG piece of paper reason to come, and actually calculate the shape and vector length of the lobes of a two element Yagi-Uda antenna... Do the calculation in both the horizonal and vertical planes... From that you can calculate the volume of each lobe, which is proportional to the percentage of power in each lobe... From that number you can very simply calculate what percentage went into the lobes you prefer and what went in the lobes you don't prefer... snip ------------ REPLY FOLLOWS ------------ The problem here is not math, it's English. You are calculating gain and/or directivity, not efficiency. Bill, W6WRT |
Yagi efficiency
Cecil Moore wrote:
He also says for a 1-dimensional aperture as a function of taper: "The aperture efficiency is a maximum with no taper, while the beam efficiency is a maximum with full taper." Oops, Kraus said that, not Balanis. -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
"Cecil Moore" wrote in message . .. Jerry Martes wrote: Can you try again to teach me how efficiency is defined?? What kind of efficiency? antenna? beam? aperture? overall? conduction-dielectric? Balanis defines overall antenna efficiency as the product of: 1. reflection (mismatch) efficiency 2. conduction efficiency 3. dielectric efficiency He gives the conduction-dielectric efficiency as: Rr/(RL + Rr) where Rr is the radiation resistance and RL is the (conduction + dielectric) losses He gives beam efficiency as: (Beam cone power)/(Total radiated power) He also says for a 1-dimensional aperture as a function of taper: "The aperture efficiency is a maximum with no taper, while the beam efficiency is a maximum with full taper." -- 73, Cecil http://www.w5dxp.com Hi Cecil How does Art define Efficiency for evaluating Yagi antennas? Jerry |
Yagi efficiency
Bill Turner wrote:
On 2 Dec 2006 05:36:05 -0800, "Denny" wrote: ... From that number you can very simply calculate what percentage went into the lobes you prefer and what went in the lobes you don't prefer... The problem here is not math, it's English. You are calculating gain and/or directivity, not efficiency. Maybe beam efficiency? (cone beam power)/(total radiated power) -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
Jerry Martes wrote:
How does Art define Efficiency for evaluating Yagi antennas? I don't know - I just joined this thread in the middle. -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
Cecil Moore wrote:
Jerry Martes wrote: How does Art define Efficiency for evaluating Yagi antennas? I don't know - I just joined this thread in the middle. Cecil: I think caution is best used. Reminds me of the three blind men who went to see the elephant, one grabbed the trunk, one a leg, the other a tail... and you know how the story goes from there. I think there is confusion between the radiated power, only allowing for resistance/dielectric losses; as opposed to why it is desirable to allow some loss introduced by other elements because the net gain of "focusing" the antenna is a benefit to you is the major crux of this whole discussion. But then, I am not even sure of that, completely! I suppose the most "efficient" antenna, with only taking into consideration the power delivered to the antenna though the feed line and actually arriving at the feed point to the antenna as the "antennas input power" in relation to the actual "power radiated" (or delivered to the ether) is what Art is looking at. And, in this one regard, I would suppose a full wave dipole with large dia conductors (to allow for skin effect), silver coated conductors and glass insulators would be the most "efficient antenna" (and allowing for a "perfect match" setup being installed.) But, where is that power going into the lobes may not make it the most desirable antenna! In the yagi, because the reflector and director are so close to the de in terms of wavelength do introduce some trivial? (depends again on perspective) losses here. And, here comes the fairies and the pinhead. JS |
Yagi efficiency
"Cecil Moore" wrote in message t... Jerry Martes wrote: How does Art define Efficiency for evaluating Yagi antennas? I don't know - I just joined this thread in the middle. i think his efficiency is (watts at the rx i want to talk to)/(watts power company is sending down the line) |
Yagi efficiency
John Smith wrote:
Cecil Moore wrote: Jerry Martes wrote: How does Art define Efficiency for evaluating Yagi antennas? I don't know - I just joined this thread in the middle. Cecil: I think caution is best used. Reminds me of the three blind men who went to see the elephant, one grabbed the trunk, one a leg, the other a tail... and you know how the story goes from there. I think there is confusion between the radiated power, only allowing for resistance/dielectric losses; as opposed to why it is desirable to allow some loss introduced by other elements because the net gain of "focusing" the antenna is a benefit to you is the major crux of this whole discussion. But then, I am not even sure of that, completely! I suppose the most "efficient" antenna, with only taking into consideration the power delivered to the antenna though the feed line and actually arriving at the feed point to the antenna as the "antennas input power" in relation to the actual "power radiated" (or delivered to the ether) is what Art is looking at. And, in this one regard, I would suppose a full wave dipole with large dia conductors (to allow for skin effect), silver coated conductors and glass insulators would be the most "efficient antenna" (and allowing for a "perfect match" setup being installed.) But, where is that power going into the lobes may not make it the most desirable antenna! In the yagi, because the reflector and director are so close to the de in terms of wavelength do introduce some trivial? (depends again on perspective) losses here. And, here comes the fairies and the pinhead. JS Of course, I always think of the parabolic reflector antenna as the "most efficient!" I have never seen one constructed for 160m (strange huh?); but when you get into ghz, why would you ever use anything else? (well, unless you wanted to chat off to someone on the side or back.) JS |
Yagi efficiency
Hi Jerry sorry that I didn't respond to you earlier but here goes
untuned elements which haveWhen you decide to get something going you need a means to get there. When you decide on the means you need to know if you are expending the minimum energy to get there In this particular case we have decided on generating a time varying field around some reradiatiung elements to obtain a radiating field of some sort Since we are applying energy to elements we want to know if the elements are doing a good job or are they losing out on energy translation by generating heat e.t.c instead of it all going where I want it to. So what we do is find out what energy we put in to obtain our objective and measure what we got out towards our objective to see how effective we were which is a measure of efficiency... Ideally we dont want to produce heat and all that other stuff but the anteena array that we have chosen to do this is a yagi array of elements which starts of with a resonant dipole which has a purely resistive impedance. But the yagi then goes on to upset things by adding which have a reactive impedance which detracts from the purly resistive value of the impedance which means losses when we should have added extra resonant elements to the set up as a means of adding to the structure to maintain zero losses BUT the yagi does go a long way towards our objectives so it has hung around for a long while. As a side issue we should also consider the environment that our array is working in and also the type of element material we are using as well as the means taken to input power but that gets more complicated so the question is really revolving around the energy input versus a magnetic near field generation that goes on to form a far field radiation field. SOOOOOOOooooo efficiency in this case compares the electrical power applied to the yagi to generate a magnetic and electric fieldaround the yagi and to check how much energy was lost on the way to our objective. Sorry for the delay but fortunately I did check back in before I moved on to other things Regards Art Jerry Martes wrote: Hi Art You know, I am really a slow learner. I still dont understand how efficiency is defined. Can you try again to teach me how efficiency is defined?? Thanks Jerry "art" wrote in message ups.com... Hi Jerry perhaps I am wrong that there ARE people who want to talk antennas We went thru this some time ago and I was referring to efficiency of the yagi antenna with respect to the radiation field where much is reflected to areas of no concern. Others did not like this and said efficiency referred to is one of the radiation facets of a radiating array and the yagi is efficient and then the sniping statrted and the newsgroup went down hill as others joined to emulate and perpetuate abrasive non antenna related subjects. I just popped back to see if the group wanted to change back to antenna talk and posted the term efficiency of the yagi in terms of radiation which everybody was auguing about. Well things haven't changed they still just want to throw stones and more will join in as the thread goes on., Ill stick it out for an hour or so and then move on again. Cant wait for somebody to compare with free space stuff to add to the confusion, I know it will come Jerry Martes wrote: "art" wrote in message ups.com... Some time ago I mentioned how inefficient Yagi design antennas were thinking more in the way of how little of the radiation used got to its required direction. At that time people said the antenna was efficient though they wanted to talk about actual radiation efficiency and the sniping began .Nobody but nobody came back with the radiation efficiency of a Yagi as they saw the question, they just wanted to throw stones.Imagine that antennas was not what the experts wanted to talk about and the newsgroup took a turn for the worst So I join in with the thoughts of radiation efficiency of a yagi unless you prefere to give up this antenna newsgroup. But before you scream out and throw stones again I will referr to efficiency as most of the members of this group what's left of them think of the term. So let's look at that if that is what you preferr.. The basic small yagi has three elements one driven, one a reflector and one a director yet only one element has a truly resistive impedance whereas the other two do not. Since two elements out of the three are producing reactive impedances and wherein the reactive portions of impedance is pure waste pray tell me how one can consider a yagi as efficient? And please, please don't waste time on "I don't understand" otherwise everything drops down to the subject of spark noise which was really decided by hams a long while ago. On the other side of the coin, if the reactive portion of an impedance is not waste then why is LCR type mesh circuitry only revolve around lumped circuitry? HINT add up the power emminating from each element P =I sq times real resistance for those who are just followers. There again maybe it is best that you be honest and say you don't understand! Better that than join those who have nothing to say about antennas! Hi Art OK, I dont understand. Perhaps I could begin to understand if I was given the definition of efficiency we are using in this discussion. How do you define efficiency? Jerry |
Yagi efficiency
"art" wrote in message ps.com... Hi Jerry sorry that I didn't respond to you earlier but here goes untuned elements which haveWhen you decide to get something going you need a means to get there. When you decide on the means you need to know if you are expending the minimum energy to get there In this particular case we have decided on generating a time varying field around some reradiatiung elements to obtain a radiating field of some sort Since we are applying energy to elements we want to know if the elements are doing a good job or are they losing out on energy translation by generating heat e.t.c instead of it all going where I want it to. So what we do is find out what energy we put in to obtain our objective and measure what we got out towards our objective to see how effective we were which is a measure of efficiency... Ideally we dont want to produce heat and all that other stuff but the anteena array that we have chosen to do this is a yagi array of elements which starts of with a resonant dipole which has a purely resistive impedance. But the yagi then goes on to upset things by adding which have a reactive impedance which detracts from the purly resistive value of the impedance which means losses when we should have added extra resonant elements to the set up as a means of adding to the structure to maintain zero losses BUT the yagi does go a long way towards our objectives so it has hung around for a long while. As a side issue we should also consider the environment that our array is working in and also the type of element material we are using as well as the means taken to input power but that gets more complicated so the question is really revolving around the energy input versus a magnetic near field generation that goes on to form a far field radiation field. SOOOOOOOooooo efficiency in this case compares the electrical power applied to the yagi to generate a magnetic and electric fieldaround the yagi and to check how much energy was lost on the way to our objective. Sorry for the delay but fortunately I did check back in before I moved on to other things Regards Art Hi Art As I read it, the efficiency (in percentage) we are using for this discussion is Power Out divided by Power In, if the "objective" is to radiate power. Or, correct me if I misread. Jerry |
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