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Yagi efficiency
When one looks at a.radiating array pattern one can see that the yagi
is very inefficient. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? I know there are a lot of different type antenna gains and arrangement but I am trying to determine in an informal way the efficiency ratio and compare it to what would appear to be a very efficient antenna such as a dish. A casual look at a yagi radiation pattern would suggest that it is less than 50% efficient at best especially when considering DX work where even the main lobe is less than 50% efficient when looking at available signal paths beyond 4000 miles which are somewhat below 12 degrees and where the main lobe itself is centered between 13 and 14 degrees with an average amateur antennah Art |
Yagi efficiency
art wrote:
When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Please define "efficiency". -- 73, Cecil, http://www.w5dxp.com |
Yagi efficiency
On 21 Sep 2006 17:05:44 -0700, "art" wrote:
When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Art, this suggests that you have an unconventional view of the meaning of the term "efficiency", perhaps you should elaborate. Owen -- |
Yagi efficiency
art wrote:
When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume Art Art Yagis, when made of almost anything but something like nichrome wire, are very efficient. Aluminum element yagis run in the high 90's of percent efficiency when properly designed. My bet is that you aren't speaking of efficiency at all, but something you don't know the words to express. Try to explain what you mean, and this group may be able to help you. tom K0TAR |
Yagi efficiency
Well this is where I am comming from, I am presently building an
antenna for this winter where I will be communicating with the U.K. Thus my major lobe needs to be robust between about 10 degtrees and 4 degrees to ensnare most of the communication. Notwithstanding that the upper half of the major lobe serves no usefull purpose to what the antenna is required for there is a mass of radiation in many directions and levels that have no connection to the required purpose of the antenna, thus we have a lot of wasted radiation that if we harness it so that it is used for the antennas primary use the efficiency of the antenna would increase immensly. So to the question, accepting that the major lobe is required in its entirety for the antennas required use I feel that less than 50% of available radiation is used for the antennas design usage and that also includes the upper lobe as not being a positive contributor However I have no real figures to hang my hat on........ O.K.? Art Tom Ring wrote: art wrote: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume Art Art Yagis, when made of almost anything but something like nichrome wire, are very efficient. Aluminum element yagis run in the high 90's of percent efficiency when properly designed. My bet is that you aren't speaking of efficiency at all, but something you don't know the words to express. Try to explain what you mean, and this group may be able to help you. tom K0TAR |
Yagi efficiency
Tom Ring wrote: art wrote: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume Art Art Yagis, when made of almost anything but something like nichrome wire, are very efficient. Aluminum element yagis run in the high 90's of percent efficiency when properly designed. Hmmmmm I would question your logic on that figure. since I am not aware of the normal ratio between actual resistance versus radiation resistance which would point to the manufacture of radiation energy relative to the total energy input however my question relates to the efficient radiation to the requirement at hand Art tom K0TAR |
Yagi efficiency
On 21 Sep 2006 19:09:38 -0700, "art" wrote:
Notwithstanding that the upper half of the major lobe serves no usefull purpose to what the antenna is required for there is a mass of radiation in many directions and levels that have no connection to the required purpose of the antenna, thus we have a lot of wasted radiation that if we harness it so that it is used for the antennas primary use the efficiency of the antenna would increase immensly. Hi Art, The classic solution is to stack yagis vertically. This draws down the higher radiation lobes and puts their gain in the forward direction. However, unless you can positively insure that higher radiation does not actually find its way to the target (you need a propagation modeler to prove that, by the way), then you could be muffling yourself at one elevation to yell at another elevation that is only heard in points remote from the target. In other words, if you suppress the lobe at 20 degrees to optimize the lobe at 10 degrees, you may miss your target altogether. Given that skip works on so many variables, an "efficient" antenna may be wholly useless. 73's Richard Clark, KB7QHC |
Yagi efficiency
Richard Clark wrote: On 21 Sep 2006 19:09:38 -0700, "art" wrote: Notwithstanding that the upper half of the major lobe serves no usefull purpose to what the antenna is required for there is a mass of radiation in many directions and levels that have no connection to the required purpose of the antenna, thus we have a lot of wasted radiation that if we harness it so that it is used for the antennas primary use the efficiency of the antenna would increase immensly. Hi Art, The classic solution is to stack yagis vertically. This draws down the higher radiation lobes and puts their gain in the forward direction. Well you are getting closer to the question at hand. You have now doubled the power input but only slightly gained directionality(2db) efficiency I would also suspect that you have flattened the lower lobe only into a pancake shape. But again I go back to the desirable radiation which can be said in this case to be the lower half of the major lobes half power envelope which for a directional radiated array is very small compared to the total radiated field.True propagation can play games but the ARRL give the average arrival angles over a 11 year period so it is not a hopeless task to get a ball park figure regarding usefull radiation knowing where the target is I suppose I could make a model and slice out the half power lobe portion and compare the two volumes for myself, I just thought that it had already been looked at Oh well back to the drawing board Art However, unless you can positively insure that higher radiation does not actually find its way to the target (you need a propagation modeler to prove that, by the way), then you could be muffling yourself at one elevation to yell at another elevation that is only heard in points remote from the target. In other words, if you suppress the lobe at 20 degrees to optimize the lobe at 10 degrees, you may miss your target altogether. Given that skip works on so many variables, an "efficient" antenna may be wholly useless. 73's Richard Clark, KB7QHC |
Yagi efficiency
On 21 Sep 2006 19:19:52 -0700, "art" wrote:
Tom Ring wrote: art wrote: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume Art Art Yagis, when made of almost anything but something like nichrome wire, are very efficient. Aluminum element yagis run in the high 90's of percent efficiency when properly designed. Hmmmmm I would question your logic on that figure. since I am not aware of the normal ratio between actual resistance versus radiation resistance which would point to the manufacture of radiation energy relative to the total energy input however my question relates to the efficient radiation to the requirement at hand Art Art, from Wikipedia and me, some definition that might help you express your problem in conventional terms: Directivity is a property of the radiation pattern produced by an antenna. It is defined as the ratio of the power radiated in a given direction to the average of the power radiated in all directions. Gain is the product of the efficiency of the antenna and the directivity. Efficiency is the ratio of total power radiated to power into the antenna. Efficiency of practical Yagis is very high as Tom has told you. Loaded / trapped Yagis are not so efficient due partly to losses in the loading coils / traps. This is the same issue that commonly arises with shortened antennas. It is quite wrong to say in general "that the yagi is very inefficient". You seem to be talking HF, the azimuth beamwidth of most practical HF Yagis is so large that you are unlikely to notice much difference in gain within 3 deg of boresight, so on a fixed heading you would expect to cover the 10 deg to 4 deg target area comfortably with little variation in gain. If you want to maximise the transmitted signal for that specific path, you should minimise losses (eg avoid lossy traps and coils, feed system losses etc), increase directivity (more elements, better design), pay attention to the desired path elevation (eg mounting height of the antenna). Owen -- |
Yagi efficiency
On 21 Sep 2006 20:16:31 -0700, "art" wrote:
give the average arrival angles over a 11 year period so it is not a hopeless task to get a ball park figure regarding usefull radiation knowing where the target is Hi Art, It is instructive for others to consider, so I shall proceed with very few of those variables considered (we can see you offer nothing in the way of time of year, time of day, frequency, Sun spot count, and so on): 20M 0000 UT Spring 5-7 deg 20M 0000 UT Summer 4 deg 20M 0000 UT Fall 6-8 deg 20M 0000 UT Winter 7 deg 20M 1200 UT Spring 3 deg 20M 1200 UT Summer 2-10 deg (depending) 20M 1200 UT Fall 2-3 deg 20M 1200 UT Winter 4-6 deg 40M 0000 UT Spring 10 deg 40M 0000 UT Summer 8-12 deg 40M 0000 UT Fall 3-12 deg (depending) 40M 0000 UT Winter 3 deg The numbers above say absolutely nothing about the probability of making a contact. If you stacked 4 to 8 yagis as high as 4 wavelengths, you might find something "efficient." 73's Richard Clark, KB7QHC |
Yagi efficiency
When one looks at a.radiating array pattern one can see that the yagi
is very inefficient. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? I know there are a lot of different type antenna gains and arrangement but I am trying to determine in an informal way the efficiency ratio and compare it to what would appear to be a very efficient antenna such as a dish. I think the parameter that you are searching for is GAIN !!!! An antenna only has gain by compressing power more into one direction more than another. It is a case of robbing Peter to pay Paul, the more power you have in the main lobe the less you have in other directions. 73 Jeff |
Yagi efficiency
I'm not sure I understand the question, but a large fraction of the
total power is typically in the main lobe of a Yagi. You won't increase the power in the main lobe significantly by reducing or eliminating other lobes, because there just isn't much power there. If you want more power in a narrower range of directions, you need more directionality, which means a longer Yagi, stacked Yagis, or some other type of antenna which will probably be larger. The methodology for and tradeoffs involved in increasing directionality are well known. And because Yagis (ones not having lossy traps or loading components) are very efficient, directionality and gain are inextricably linked. Roy Lewallen, W7EL |
Yagi efficiency
It occurs to me that by art's definition, all antennas are
"inefficient". When you're talking with someone, only a teeny, tiny fraction of the radiated power is going precisely in the right direction to be collected by his antenna, so the remainder is wasted. Shucks, I'd be amazed if the "efficiency" of the best HF antenna is better than 0.001% by this criterion. Roy Lewallen, W7EL |
Yagi efficiency
The other point I note is that he wants enhanced HF radiation between
10 and 4 degrees elevation and apparently beamed to a specific point on the globe... The cubic size and the towers and the arrays that it will take to accomplish this are not efficient in time, money, and effort... He is chasing a unicorn... As has been pointed out already, the percentage of time that the major portion of the arriving HF EM wave is below 10 degrees can be enumerated on the fingers of one hand... Besides, who is going to have the array on the other end with comparable response? denny / k8do |
Yagi efficiency
"art" wrote in message ups.com... Richard Clark wrote: On 21 Sep 2006 19:09:38 -0700, "art" wrote: Notwithstanding that the upper half of the major lobe serves no usefull purpose to what the antenna is required for there is a mass of radiation in many directions and levels that have no connection to the required purpose of the antenna, thus we have a lot of wasted radiation that if we harness it so that it is used for the antennas primary use the efficiency of the antenna would increase immensly. Hi Art, The classic solution is to stack yagis vertically. This draws down the higher radiation lobes and puts their gain in the forward direction. Well you are getting closer to the question at hand. You have now doubled the power input but only slightly gained directionality(2db) efficiency I would also suspect that you have flattened the lower lobe only into a pancake shape. But again I go back to the desirable radiation which can be said in this case to be the lower half of the major lobes half power envelope which for a directional radiated array is very small compared to the total radiated field.True propagation can play games but the ARRL give the average arrival angles over a 11 year period so it is not a hopeless task to get a ball park figure regarding usefull radiation knowing where the target is I suppose I could make a model and slice out the half power lobe portion and compare the two volumes for myself, I just thought that it had already been looked at Oh well back to the drawing board Art what you are missing is the variability in that arrival angle. if you are interested in a specific path you must be able to receive all the possible arrival angles, which with yagi's requires mounting several of them at different heights. for instance consider a path from w1 to western europe at the sunspot peak on 10m... it is not uncommon for the band to open at a very low angle, say where a single yagi at 120' is the best antenna, then as the day progresses the angle increases so much that the 120' antenna is almost worthless but one at only 30' is working great. if you put everything into getting that 10-12 degree angle you lose out by mid morning when the arrival angle is up to 30 degrees or more... but at the same time that top antenna may be working great into siberia! what you are looking for is not normally called 'efficiency', but 'directivity'. unfortunately horizontally polarized yagi's vertical radiation pattern is very dependent on height and the terrain so increasing the directivity is seen mostly in the width of the pattern. and as noted above, controlling the vertical pattern is normally done by changing the antenna height, usually by stacking multiple antennas on the tower and selecting them one at a time or in combinations to give the desired vertical coverage. There have been some experiments with variable phasing of stacked yagis, but it is not a common capability in amateur installations. |
Yagi efficiency
You are right... You are so far ahead of this group that we can not
even comprehend the question... denny art wrote: Gentlemen let me reiterate |
Yagi efficiency
Thank you for those kind words but I will keep trying
Art Denny wrote: You are right... You are so far ahead of this group that we can not even comprehend the question... denny art wrote: Gentlemen let me reiterate |
Yagi efficiency
Right on Jeff
Obviously I would like to rob Peter of everything he stole and give it to Paul because he is doing something constructive with his energy where as Peter is robbing energy and just throwing it away If Paul had posession of that energy then his half power beam width would increase as opposed to decreasing in the pursuit of gain using the small amount of radiation available to him Art Jeff wrote: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? I know there are a lot of different type antenna gains and arrangement but I am trying to determine in an informal way the efficiency ratio and compare it to what would appear to be a very efficient antenna such as a dish. I think the parameter that you are searching for is GAIN !!!! An antenna only has gain by compressing power more into one direction more than another. It is a case of robbing Peter to pay Paul, the more power you have in the main lobe the less you have in other directions. 73 Jeff |
Quote:
The Man in the Maze QRV at Baboquivari Peak, AZ |
Yagi efficiency
"Denny" wrote in message oups.com... You are right... You are so far ahead of this group that we can not even comprehend the question... Denny, This is all apparently intended as a guessing game, as art has given us just one single parameter of the exercise --- he wants to communicate with the UK in the winter. From where? At what time(s) of day? On what QRG(s)? What construction constraints? (budget, zoning, etc.) 73, de Hans, K0HB -- Homepage: http://www.home.earthlink.net/~k0hb Member: ARRL http://www.arrl.org SOC http://www.qsl.net/soc VWOA http://www.vwoa.org A-1 Operator Club http://www.arrl.org/awards/a1-op/ TCDXA http://www.tcdxa.org MWA http://www.w0aa.org TCFMC http://www.tcfmc.org FISTS http://www.fists.org LVDXA http://www.upstel.net/borken/lvdxa.htm NCI http://www.nocode.org |
Yagi efficiency
Hans, you are so full of it, like Andy Capp waving his hands around in
the air to vent his fraustration. Go back to the initial posting and what it says. All of your comments refer to side issues brought up that are not relavent to the initial question wthich also is not a guessing game to those skilled in the art Ar KØHB wrote: "Denny" wrote in message oups.com... You are right... You are so far ahead of this group that we can not even comprehend the question... Denny, This is all apparently intended as a guessing game, as art has given us just one single parameter of the exercise --- he wants to communicate with the UK in the winter. From where? At what time(s) of day? On what QRG(s)? What construction constraints? (budget, zoning, etc.) 73, de Hans, K0HB -- Homepage: http://www.home.earthlink.net/~k0hb Member: ARRL http://www.arrl.org SOC http://www.qsl.net/soc VWOA http://www.vwoa.org A-1 Operator Club http://www.arrl.org/awards/a1-op/ TCDXA http://www.tcdxa.org MWA http://www.w0aa.org TCFMC http://www.tcfmc.org FISTS http://www.fists.org LVDXA http://www.upstel.net/borken/lvdxa.htm NCI http://www.nocode.org |
Yagi efficiency
On Fri, 22 Sep 2006 03:32:13 -0700, Roy Lewallen
wrote: "efficiency" of the best HF antenna is better than 0.001% by this criterion. Hi Roy, Not far off. If absolutely EVERYONE (presuming 6 billion of us) on the planet got art's signal at S9 from a 100W transmission, that would only be 300 mW captured (0.3% efficient). I suppose the 99.7W lost would contribute to Intergalactic Warming (which would be 99.7% efficient). However, HF temperature is for all practicable purposes indistinguishable from absolute Zero. 73's Richard Clark, KB7QHC |
Yagi efficiency
Neat
Art Richard Clark wrote: On Fri, 22 Sep 2006 03:32:13 -0700, Roy Lewallen wrote: "efficiency" of the best HF antenna is better than 0.001% by this criterion. Hi Roy, Not far off. If absolutely EVERYONE (presuming 6 billion of us) on the planet got art's signal at S9 from a 100W transmission, that would only be 300 mW captured (0.3% efficient). I suppose the 99.7W lost would contribute to Intergalactic Warming (which would be 99.7% efficient). However, HF temperature is for all practicable purposes indistinguishable from absolute Zero. 73's Richard Clark, KB7QHC |
Yagi efficiency
Dave wrote: "art" wrote in message ups.com... Richard Clark wrote: On 21 Sep 2006 19:09:38 -0700, "art" wrote: Notwithstanding that the upper half of the major lobe serves no usefull purpose to what the antenna is required for there is a mass of radiation in many directions and levels that have no connection to the required purpose of the antenna, thus we have a lot of wasted radiation that if we harness it so that it is used for the antennas primary use the efficiency of the antenna would increase immensly. Hi Art, The classic solution is to stack yagis vertically. This draws down the higher radiation lobes and puts their gain in the forward direction. Well you are getting closer to the question at hand. You have now doubled the power input but only slightly gained directionality(2db) efficiency I would also suspect that you have flattened the lower lobe only into a pancake shape. But again I go back to the desirable radiation which can be said in this case to be the lower half of the major lobes half power envelope which for a directional radiated array is very small compared to the total radiated field.True propagation can play games but the ARRL give the average arrival angles over a 11 year period so it is not a hopeless task to get a ball park figure regarding usefull radiation knowing where the target is I suppose I could make a model and slice out the half power lobe portion and compare the two volumes for myself, I just thought that it had already been looked at Oh well back to the drawing board Art what you are missing is the variability in that arrival angle. if you are interested in a specific path you must be able to receive all the possible arrival angles, which with yagi's requires mounting several of them at different heights. for instance consider a path from w1 to western europe at the sunspot peak on 10m... it is not uncommon for the band to open at a very low angle, say where a single yagi at 120' is the best antenna, then as the day progresses the angle increases so much that the 120' antenna is almost worthless but one at only 30' is working great. if you put everything into getting that 10-12 degree angle you lose out by mid morning when the arrival angle is up to 30 degrees or more... David that is not absolutely correct, we are talking about a single point to point communication where the arrival angle is below 10 degrees. If the angle of arrival is above that then it is created by unusual propagation or deflection of radiation path. For a given distance one can say that the communication energy level is comensurate with the number of skips taken where a point is reached when the number of skips controls the amount of energy left at the communication distance. Thus the east may hear the west coast talking to Europe where they cannot hear the transmitting station because of the excessive number of hops. Remember, I am talking about point to point communication which largely defined by the number of skips taken which is why dipole to dipole transmissions are pushed aside for those desiring DX contacts tho I am sure you are not advocating dipoles for DX. but at the same time that top antenna may be working great into siberia! what you are looking for is not normally called 'efficiency', but 'directivity'. unfortunately horizontally polarized yagi's vertical radiation pattern is very dependent on height do you really mean "vertical: radiation pattern? and the terrain so increasing the directivity is seen mostly in the width of the pattern. and as noted above, controlling the vertical pattern is normally done by changing the antenna height, usually by stacking multiple antennas on the tower and selecting them one at a time or in combinations to give the desired vertical coverage. No... stacking is used purely to provide a vector to combat the earths magnetic field which affects all radiation directional patterns not only a vertical pattern There have been some experiments with variable phasing of stacked yagis, but it is not a common capability in amateur installations. Exactly since these methods provide a vectoir to counteract the terrains magnetic field unfortunately this requires extra power supply points where the desire is for just one. Art |
Yagi efficiency
Roy Lewallen wrote: I'm not sure I understand the question, but a large fraction of the total power is typically in the main lobe of a Yagi. You won't increase the power in the main lobe significantly by reducing or eliminating other lobes, because there just isn't much power there. Roy you know better than that ! gain is a binomial function with respect to the forward radiation at the point of initiation. It does nothing to salvalge energy expended in the reaward direction, to do that another vector is required that cannot be produced by a planar array. As far as traps being lossy as if they get hot or something that is also untrue, what you are seeing is a radiation field created by the trap that is in opposition to that created on the element i.e. a field that is 180 degrees out of phase If you want more power in a narrower range of directions, you need more directionality, which means a longer Yagi, stacked Yagis, or some other type of antenna which will probably be larger. The methodology for and tradeoffs involved in increasing directionality are well known. And because Yagis (ones not having lossy traps or loading components) are very efficient, directionality and gain are inextricably linked. Again I do not agree that Yagis are efficient Art Roy Lewallen, W7EL |
Yagi efficiency
art wrote:
Roy Lewallen wrote: I'm not sure I understand the question, but a large fraction of the total power is typically in the main lobe of a Yagi. You won't increase the power in the main lobe significantly by reducing or eliminating other lobes, because there just isn't much power there. Roy you know better than that ! gain is a binomial function with respect to the forward radiation at the point of initiation. It does nothing to salvalge energy expended in the reaward direction, to do that another vector is required that cannot be produced by a planar array. Sorry, I can't make the slightest amount of sense out of this. As far as traps being lossy as if they get hot or something that is also untrue, what you are seeing is a radiation field created by the trap that is in opposition to that created on the element i.e. a field that is 180 degrees out of phase Egad. There's no point in my wasting time by attempting to contribute further to this. I'll leave you to your alternate reality. Roy Lewallen, W7EL |
Yagi efficiency
Roy Lewallen wrote:
Egad. There's no point in my wasting time by attempting to contribute further to this. I'll leave you to your alternate reality. Now you know how I felt after your posting questioning (denying?) the existence of reflected energy. -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
Cecil Moore wrote: Roy Lewallen wrote: Egad. There's no point in my wasting time by attempting to contribute further to this. I'll leave you to your alternate reality. Now you know how I felt after your posting questioning (denying?) the existence of reflected energy. -- 73, Cecil http://www.w5dxp.com Cecil as I said in another posting it takes a generation for change to be accepted. Until then the common response is I don't understand because their education followed a well trodden path where memory was the accepted path to success. Unfortunately this allowed things outside the trodden path to be bypassed as the great unknown. Note that Roy did not give a sensible response only theatrics to either of the things I pointed out because conflict often prevents reasonable thought with an open mind. If theire was no conflict in his mind he would have trotted out how the radiation to the front is enhanced by radiation to the rear that is if he had the answer.......but he does not . As far as reflections go that was not part of his education itiniary so he will go with the flow. Roy is an expert in his particular field because he has a good memory take him outside that boundary and he becomes a different person and pouts Fortunately he said he is not going to bother me any more so that it is my hand hand ithat is lifted .Shame that Reg is not around to witness his feux par Art |
Yagi efficiency
On 21 Sep 2006 17:05:44 -0700, "art" wrote:
Hi Art, To close this out, we have discovered through the various correspondents that: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Is false. That much is clear through evidence, no theory necessary. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? Yes, someone does. It was pointed out quite clearly that ALL the gain from sidelobe or back lobe could not be assembled into very much constructive gain. Economists call this the law of diminishing return. A casual look at a yagi radiation pattern would suggest that it is less than 50% efficient at best Is false. One can certainly contrive for abysmal efficiency (you use mylar and bamboo in place of tubing don't you?); but that does not make the range of yagis fall into disrepute through aberrations of one designer. especially when considering Is false - there are no externalities, except local ground loss, to an antenna (and that exception is because ground is part of the radiating system). DX work where even the main lobe is less than 50% efficient when looking at available signal paths beyond 4000 miles which are somewhat below 12 degrees and where the main lobe itself is centered between 13 and 14 degrees with an average amateur antennah You don't have any choice in the matter. No element pair is ever going to offer better. No single yagi is going to draw the peak launch angle down to the elevations I've already identified. A stack of yagis is hardly likely either. The long and short of it is that you are facing 0.001% "efficiency" without any probable method to even budge it up to 0.0015%. Creationist scienze might help tho'. 73's Richard Clark, KB7QHC |
Yagi efficiency
On Fri, 22 Sep 2006 13:21:47 -0700, Roy Lewallen
wrote: Egad. There's no point in my wasting time by attempting to contribute further to this. I'll leave you to your alternate reality. Roy, it was obviously a troll, and many of us have been caught (again). Art's lead in "one can see that the yagi is very inefficient" should have been recognised by us all as bait. Owen -- |
Yagi efficiency
Owen Duffy wrote:
... recognised ... Hey Owen, my spellchecker caught that. What's wrong with your spellchecker? :-) -- 73, Cecil http://www.w5dxp.com |
Yagi efficiency
Owen Duffy wrote:
On Fri, 22 Sep 2006 13:21:47 -0700, Roy Lewallen wrote: Egad. There's no point in my wasting time by attempting to contribute further to this. I'll leave you to your alternate reality. Roy, it was obviously a troll, and many of us have been caught (again). Art's lead in "one can see that the yagi is very inefficient" should have been recognised by us all as bait. No, whatever art's problems are, I don't believe he's a troll. I'm confident that he's sincere in his statements and questions. It's just that he often makes no sense to me, and when he does, it's sometimes so contrary to established physics that it's reminiscent of the new age folks. His unconventional use of "efficiency" is typical, like the use of "energy" by the paraphysical crowd. Once in a while I make an honest try to contribute something rational, but usually end up just making him mad and provoking even sillier statements -- as happened again this time. So there's really no point in it. Roy Lewallen, W7EL |
Yagi efficiency
art wrote:
When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? I know there are a lot of different type antenna gains and arrangement but I am trying to determine in an informal way the efficiency ratio and compare it to what would appear to be a very efficient antenna such as a dish. A casual look at a yagi radiation pattern would suggest that it is less than 50% efficient at best especially when considering DX work where even the main lobe is less than 50% efficient when looking at available signal paths beyond 4000 miles which are somewhat below 12 degrees and where the main lobe itself is centered between 13 and 14 degrees with an average amateur antennah Art Ok, I reread the original post, and it is right here. The problem is that you need to understand that the angular center of the main lobe is dependant on the height of the beam above the ground, so this part - where the main lobe itself is centered between 13 and 14 degrees with an average amateur antennah is actually a variable. Here lies your problem. tom K0TAR |
Yagi efficiency
Richard Clark wrote: On 21 Sep 2006 17:05:44 -0700, "art" wrote: Hi Art, To close this out, we have discovered through the various correspondents that: When one looks at a.radiating array pattern one can see that the yagi is very inefficient. Is false. That much is clear through evidence, no theory necessary. Does anybody know of the relative volume contained in the main radiation lobe versus the total volume of the entire pattern? Yes, someone does. It was pointed out quite clearly that ALL the gain from sidelobe or back lobe could not be assembled into very much constructive gain. Economists call this the law of diminishing return. A casual look at a yagi radiation pattern would suggest that it is less than 50% efficient at best Is false. One can certainly contrive for abysmal efficiency (you use mylar and bamboo in place of tubing don't you?); but that does not make the range of yagis fall into disrepute through aberrations of one designer. especially when considering Is false - there are no externalities, except local ground loss, to an antenna (and that exception is because ground is part of the radiating system). DX work snip That was funny You don't have any choice in the matter. No element pair is ever going to offer better. No element pair etc pretty specific statement which offers safety No single yagi is going to draw the peak ............................ But you are sticking with the inefficient Yagi, that should make it a safe statement I would listen more intently if you stated that the angle cannot be drawn down regardless of the array used launch angle down to the elevations I've already identified. A stack of yagis is hardly likely either. Again you cover yourself my involving the inefficient Yagi The long and short of it is that you are facing 0.001% "efficiency" without any probable method to even budge it up to 0.0015%. Creationist scienze might help tho'. 73's Richard Clark, KB7QHC Well it still gave me a laugh seeing you seeking safety in the Yagi shadow Do you also agree with what Roy said in a senior moment about wasted yagi energy? Art |
Yagi efficiency
On Fri, 22 Sep 2006 22:52:16 GMT, Cecil Moore
wrote: Owen Duffy wrote: ... recognised ... Hey Owen, my spellchecker caught that. What's wrong with your spellchecker? :-) Nothing Cecil. I use Agent which is an "internationalised" product, and has an "English (International)" spell check option. Works fine! I see you have had BOG trying to correct American spelling (re the gas comment a few days back). We have learnt to ignore him over here. Owen -- |
Yagi efficiency
art wrote:
snip No... stacking is used purely to provide a vector to combat the earths magnetic field which affects all radiation directional patterns not only a vertical pattern Ok, now I give up. Forget the posting I sent a few minutes ago. Kook alert! tom K0TAR |
Yagi efficiency
On 22 Sep 2006 16:15:41 -0700, "art" wrote:
You don't have any choice in the matter. No element pair is ever going to offer better. No element pair etc pretty specific statement which offers safety Hi Art, Safety? The world recognizes a dry comment that is factual and does not attach notions of sensation to it. [Fair warning to the alliteration intolerant.] Fantasy fear (from prophecies) is called the Pathetic Fallacy. I would listen more intently if you stated that the angle cannot be drawn down regardless of the array used Another fallacy. Art, no one believes you would.... aw let's just test the hypothesis to expose another fallacy: The angle cannot be drawn down to those needed regardless of the array used. You haven't got a chance at all. You are fated to cower forever as being "inefficient" without any brighter prospects ever. Do you also agree with what Roy said in a senior moment about wasted yagi energy? He wasted a lot of energy on you, Old Man, didn't he? Still frightened? They say if you talk about your nightmares, they will go away. I heard that last night in a movie "This Gun For Hire" as told by Raven (Alan Ladd) to Veronica Lake. [This thread needs a modicum of real entertainment value now that all technical content has been drained.] 73's Richard Clark, KB7QHC |
Yagi efficiency
Dear Neighbor Denny:
1. One may have reasonably smooth HF radiation between 4 and 10 degrees with a yagi that is a little over two WL (2.2) above ground (with a maximum of about 7 degrees). The second null will be in the neighborhood of 14 degrees. 2. Many "DXers" exist who have antennas that even at 14 MHz are two WL high. Money-efficiency is very much an individual thing. 3. Many years of dealing with arrival angles of HF signals from over 7 Mm away suggests that such angles are mostly smaller than ten degrees. Larger than 12 or 13 and smaller than about 2 degrees is unusual. With truly serious antennas on both ends, as you have suggested, one might see 1 to 4 degrees. 4. Great to know that we are both still alive. It has been a long time since we have talked. 73, Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: "Denny" wrote in message ups.com... The other point I note is that he wants enhanced HF radiation between 10 and 4 degrees elevation and apparently beamed to a specific point on the globe... The cubic size and the towers and the arrays that it will take to accomplish this are not efficient in time, money, and effort... He is chasing a unicorn... As has been pointed out already, the percentage of time that the major portion of the arriving HF EM wave is below 10 degrees can be enumerated on the fingers of one hand... Besides, who is going to have the array on the other end with comparable response? denny / k8do |
Yagi efficiency
"art" wrote in message ups.com... snip ... to vent his fraustration. snip "Fraustration," eh? So that's it: He's upset with his wife!! |
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