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Lumped Load Models v. Distributed Coils
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Wes, Do you really think that it makes ~that~ much difference? 'Doc |
On Tue, 27 Jan 2004 00:27:15 -0600, 'Doc wrote:
| | |Wes, | Do you really think that it makes ~that~ much |difference? | 'Doc Yes... or no... or maybe, depending on what "it" is and how much difference "it" does or does not make. Regards, Wes |
On Tue, 27 Jan 2004 05:43:07 -0700, Wes Stewart
wrote: On Tue, 27 Jan 2004 00:27:15 -0600, 'Doc wrote: | | |Wes, | Do you really think that it makes ~that~ much |difference? | 'Doc Yes... or no... or maybe, depending on what "it" is and how much difference "it" does or does not make. Regards, Wes Hi Wes, The difference in your examination satisfyingly amounts to: 1.) the absence of ego towering over the problem; 1a.) the corresponding lack of sneer review that reduces the argument to "you won't change my mind"; 2.) the presence of clear unequivocal study of the problem; 3.) less than 1dB. 73's Richard Clark, KB7QHC |
On Tue, 27 Jan 2004 16:44:50 GMT, Richard Clark
wrote: |On Tue, 27 Jan 2004 05:43:07 -0700, Wes Stewart |wrote: |On Tue, 27 Jan 2004 00:27:15 -0600, 'Doc wrote: || || ||Wes, || Do you really think that it makes ~that~ much ||difference? || 'Doc | |Yes... or no... or maybe, depending on what "it" is and how much |difference "it" does or does not make. |Regards, |Wes | |Hi Wes, | |The difference in your examination satisfyingly amounts to: |1.) the absence of ego towering over the problem; |1a.) the corresponding lack of sneer review that | reduces the argument to "you won't change my mind"; |2.) the presence of clear unequivocal study of the problem; |3.) less than 1dB. Thanks! Wes |
Wes wrote,
Message-id: www.qsl.net/n7ws Follow the links. Very good, but what is "current moment?" 73, Tom Donaly, KA6RUH |
It's more of a math term than an antenna term. I believe this refers to the
'method of moments' used to calculate the far field. Take the currents in all the little sections of the antenna and sum the contributions of each for the total field...like what happens in real life. Steve N. "Tdonaly" wrote in message ... Wes wrote, Message-id: www.qsl.net/n7ws Follow the links. Very good, but what is "current moment?" 73, Tom Donaly, KA6RUH |
Steve wrote,
It's more of a math term than an antenna term. I believe this refers to the 'method of moments' used to calculate the far field. Take the currents in all the little sections of the antenna and sum the contributions of each for the total field...like what happens in real life. Steve N. Thanks Steve. The way the fellow used it it sounded like a single quantity the square of which was proportional to the radiation resistance. People who write articles for journals sometimes get a bit fanciful in their terminology. 73, Tom Donaly, KA6RUH |
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Richard wrote,
Hi Fellows, I dunno. When I read it, it looked like a reference to graphical analysis or the projection of a point that represents a mean within a surface area (which, again, harkens back to the "sinusoidal" current distribution curve). 73's Richard Clark, KB7QHC Hi Richard, it would be interesting, and very useful, too, if it were possible to characterize radiation resistance this way. I was hoping Wes would enlighten us. 73, Tom Donaly, KA6RUH |
Wes wrote, On 28 Jan 2004 06:32:47 GMT, (Tdonaly) wrote: |Richard wrote, | |Hi Fellows, | |I dunno. When I read it, it looked like a reference to graphical |analysis or the projection of a point that represents a mean within a |surface area (which, again, harkens back to the "sinusoidal" current |distribution curve). | |73's |Richard Clark, KB7QHC | | |Hi Richard, | it would be interesting, and very useful, too, if it were |possible to characterize radiation resistance this way. I was hoping |Wes would enlighten us. Let's let Hansen do that. http://www.qsl.net/n7ws/HansenPaper.pdf O.k., so he is writing about a moment method analysis. I hope Yuri and Cecil read this along with your results, Wes. Cecil can't possibly argue with this... I take that back, Cecil could argue with the Devil about how hot hell should be, so maybe this won't stop him after all. 73, Tom Donaly, KA6RUH |
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Cecil and Yuri have been uncharacteristically silent, at least about this thread since I started it. Frankly I expected some flak. Regards, Wes Howdy anteneers, I have been characteristically absent from the freezing NE, enjoying Bahama Mammas near Nassau, shaking off cold or flu, operating as C6AYB in CQ 160m contest (beat world Low Power world record) with IC706 and piece of wire in the form of Half Sloper from the balcony down to a palm tree and getting some badly needed tan for my sickly pale complexion. Sorry for missing some of the coil battles. As far as flak, I glanced over the mentioned paper and deducted that relates to some calculated "facts" rather than measured. So far I have concluded that we have reached point of (dis)agreement between two sides, and as I mentioned, there is not much point in arguing. W8JI tried to prove his "truth," only to measure differences in coil current (not showing details about the setup) and while insisting he is right, proving that he is wrong. As I mentioned, weather permitting, I will do more measurements, describe them in an article. In the mean time, if anyone else made the measurements, please describe them along with the description of setup (length of radiator parts, placements of coil, frequencies, etc.) Otherwise, you have to patient until I get around doing it, I have life and priorities outside of NG. I started reading Marc Seifer book "Wizard" - The life and times of Nikola Tesla, fascinating insight and chronology of this greatest engineering genius and the hurdles he had to overcome from the flat earth society. 73 Yuri, K3BU |
Tdonaly wrote:
O.k., so he is writing about a moment method analysis. I hope Yuri and Cecil read this along with your results, Wes. Cecil can't possibly argue with this... I take that back, Cecil could argue with the Devil about how hot hell should be, so maybe this won't stop him after all. I will argue about any software package that doesn't agree with reality. If the moment method assumes coils with no distributed capacitance, it is wrong in certain cases. Will the moment method simulate the 180 degree phase shift in Kraus' self-resonant loading coils? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Wes Stewart wrote:
Cecil and Yuri have been uncharacteristically silent, at least about this thread since I started it. Frankly I expected some flak. I haven't been paying attention. What's the bottom line? Another software package that assumes current travels through a coil at faster than the speed of light? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil wrote,
Tdonaly wrote: O.k., so he is writing about a moment method analysis. I hope Yuri and Cecil read this along with your results, Wes. Cecil can't possibly argue with this... I take that back, Cecil could argue with the Devil about how hot hell should be, so maybe this won't stop him after all. I will argue about any software package that doesn't agree with reality. If the moment method assumes coils with no distributed capacitance, it is wrong in certain cases. Will the moment method simulate the 180 degree phase shift in Kraus' self-resonant loading coils? -- 73, Cecil http://www.qsl.net/w5dxp Have you ever actually made one of these magical coils, Cecil? If you have, will you tell me how to do it? Did you read Wes' material? 73, Tom Donaly, KA6RUH |
Tdonaly wrote:
Have you ever actually made one of these magical coils, Cecil? If you have, will you tell me how to do it? It ain't rocket science, Tom, and it ain't magic. Do you understand self- resonance? Every coil is self-resonant on some frequency. Build the antenna for whatever that frequency is. My Diamond 440 MHz mobile antenna uses a phase reversing coil to phase a 1/4WL element with the 1/2WL element directly above yielding a fair amount of gain over a single 1/4WL element. Did you read Wes' material? That .pdf file locks up my computer during downloading. I may need an upgrade to my Adobe Acrobat reader. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil wrote,
Wes Stewart wrote: Cecil and Yuri have been uncharacteristically silent, at least about this thread since I started it. Frankly I expected some flak. I haven't been paying attention. What's the bottom line? Another software package that assumes current travels through a coil at faster than the speed of light? -- 73, Cecil http://www.qsl.net/w5dxp How fast does light travel in copper, Cecil? 73, Tom Donaly, KA6RUH |
On Wed, 28 Jan 2004 22:06:11 -0600, Cecil Moore
wrote: |Tdonaly wrote: | O.k., so he is writing about a moment method analysis. I hope Yuri and | Cecil read this along with your results, Wes. Cecil can't possibly argue | with this... I take that back, Cecil could argue with the Devil about how | hot hell should be, so maybe this won't stop him after all. | |I will argue about any software package that doesn't agree with reality. So "reality" exists when the software gives you the answer you expect: http://www.qsl.net/w5dxp/current.htm but is useless otherwise? You trust it to analyze linear conductors and inductive stubs that have inductance and capacitance per unit length but conclude that it is flawed when the conductor is coiled up a bit. Interesting. |If the moment method assumes coils with no distributed capacitance, Did you bother to read Rhea's paper? http://www.eagleware.com/pdf/apps/20...ngSolenoid.pdf | it |is wrong in certain cases. Will the moment method simulate the 180 degree |phase shift in Kraus' self-resonant loading coils? |
So "reality" exists when the software gives you the answer you expect:
http://www.qsl.net/w5dxp/current.htm but is useless otherwise? Maybe more like answer that reflects reality? You trust it to analyze linear conductors and inductive stubs that have inductance and capacitance per unit length but conclude that it is flawed when the conductor is coiled up a bit. Interesting. Isn't it interesting that loading stubs and coils, having the same inductance do the same amount of shortening of the wip, same effect, but when modeling programs model it, they show different current distribution? Funny logic? What about coax choke used at the antenna feedpoint? Have not heard "reason" for different RF current at both ends. It chokes, doesn't it? Huh? Yuri |
Wes Stewart wrote:
wrote: |I will argue about any software package that doesn't agree with reality. So "reality" exists when the software gives you the answer you expect: Come on, Wes. Reality exists when the software *accurately* models inductance, capacitance, and resistance. Software packages that assume zero distributed capacitance in a real-world coil are simply inaccurate for certain applications. For instance, Kraus' phase-reversing coil cannot be modeled in EZNEC, at least not as a single coil in a straight forward manner. Do you have any suggestions about using EZNEC (or other MOM software) to model the phased array antenna described by Kraus on page 824 of _Antennas_for_all_Applications, 3rd edition, which uses two phase-reversing coils? So the question still stands. Can you model Kraus' phase-reversing coil using the method of moments? If so, and the coil is not perfectly tuned and perfectly installed, you will have current flowing into both ends of the coil at the same time. I am not a MOM expert, so I don't know the answer. EZNEC seems to model phase-reversing stubs just fine. You trust it to analyze linear conductors and inductive stubs that have inductance and capacitance per unit length but conclude that it is flawed when the conductor is coiled up a bit. Interesting. EZNEC seems to model inductive stubs just fine so I have no reason to distrust it. EZNEC fails to give the same results for an inductive stub Vs a lumped inductive reactance because it doesn't model real-world coils. It will not model Kraus' phase-reversing coil and gives erroneous results when an antenna using phase-reversing coils is modeled. I have the EZNEC files that demonstrate that fact if you would like to have them. Did you bother to read Rhea's paper? http://www.eagleware.com/pdf/apps/20...ngSolenoid.pdf This is the first I have heard of it. I will read it this afternoon at work. I can't download .pdf files at home. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
On 29 Jan 2004 13:38:56 GMT, oUsama (Yuri Blanarovich)
wrote: |So "reality" exists when the software gives you the answer you expect: |http://www.qsl.net/w5dxp/current.htm |but is useless otherwise? | |Maybe more like answer that reflects reality? | |You trust it to analyze linear conductors |and inductive stubs that have inductance and capacitance per unit |length but conclude that it is flawed when the conductor is coiled up |a bit. Interesting. | |Isn't it interesting that loading stubs and coils, having the same inductance |do the same amount of shortening of the wip, same effect, but when modeling |programs model it, they show different current distribution? Funny logic? | | |What about coax choke used at the antenna feedpoint? Have not heard "reason" |for different RF current at both ends. It chokes, doesn't it? Huh? Sorry, I've taken all of the jabs at this tarbaby that I care to. I spent a lot of time preparing the paper that I published and it "reflects reality" as I see it, until proven otherwise. I would think that the pair of you would give a Howard Dean, Yeeeeaaaaa! yell and claim that my findings proved your point that the current is different at the two ends of the loading coil. Go figure. Wes |
On Wed, 28 Jan 2004 22:08:40 -0600, Cecil Moore
wrote: I haven't been paying attention. Obviously Danny, K6MHE |
Wes Stewart wrote:
Sorry, I've taken all of the jabs at this tarbaby that I care to. I spent a lot of time preparing the paper that I published and it "reflects reality" as I see it, until proven otherwise. What is the name of your paper, Wes? I don't remember you mentioning it before. All I have seen from your postings is ..pdf files of the work of others. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Dan Richardson wrote:
wrote: I haven't been paying attention. Obviously The original posting made no assertions and was simply a URL which didn't respond when I tried to access it. The subsequent postings seemed to be concerned with radiation resistance so I didn't even read them. How does radiation resistance affect the loading coil discussion? It has already been proven that EZNEC's lumped circuit model doesn't work for Kraus' real world loading coils. What else is there to say? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
On Thu, 29 Jan 2004 10:00:38 -0600, Cecil Moore
wrote: |Wes Stewart wrote: | Sorry, I've taken all of the jabs at this tarbaby that I care to. I | spent a lot of time preparing the paper that I published and it | "reflects reality" as I see it, until proven otherwise. | |What is the name of your paper, Wes? I don't remember you |mentioning it before. All I have seen from your postings is |.pdf files of the work of others. I began this thread with a pointer to: http://www.qsl.net/n7ws/Loaded%20antennas.htm |
Wes Stewart wrote:
I began this thread with a pointer to: http://www.qsl.net/n7ws/Loaded%20antennas.htm Sorry, that page wouldn't load on my computer at the time so I never read it. I will read it this afternoon. In the meantime, is there anything in the paper that will defeat the following argument? Consider a mobile helical antenna for 75m. Will anyone assert that the current at the bottom of the antenna is equal to the current at the tip of the antenna? Add a one foot stinger and reduce the length of the helical until it is again resonant. Will anyone assert that the current into the antenna is equal to the current into the stinger? Make the stinger two feet and resonate the antenna. Will anyone assert that the current into the antenna is equal to the current into the stinger? Keep up this iteration until the current into the coil is equal to the current out of the coil. At exactly what length of coil does the current taper magically disappear? -- 73, Cecil, W5DXP |
Cecil wrote,
Tdonaly wrote: Have you ever actually made one of these magical coils, Cecil? If you have, will you tell me how to do it? It ain't rocket science, Tom, and it ain't magic. Do you understand self- resonance? Every coil is self-resonant on some frequency. Build the antenna for whatever that frequency is. My Diamond 440 MHz mobile antenna uses a phase reversing coil to phase a 1/4WL element with the 1/2WL element directly above yielding a fair amount of gain over a single 1/4WL element. Did you read Wes' material? That .pdf file locks up my computer during downloading. I may need an upgrade to my Adobe Acrobat reader. -- 73, Cecil http://www.qsl.net/w5dxp So any coil that is self-resonant at the antenna's frequency will do? 73, Tom Donaly, KA6RUH |
Cecil wrote,
EZNEC seems to model inductive stubs just fine so I have no reason to distrust it. EZNEC fails to give the same results for an inductive stub Vs a lumped inductive reactance because it doesn't model real-world coils. It will not model Kraus' phase-reversing coil and gives erroneous results when an antenna using phase-reversing coils is modeled. I have the EZNEC files that demonstrate that fact if you would like to have them. Cecil, you can't even give a coherent explanation of how or why Kraus "phase reversing coil" works, or how it relates to Wes' work. I would expect any coil would work between two half-wave dipoles, but maybe not at the frequencies you expect, and certainly not just because Kraus said so. 73, Tom Donaly, KA6RUH |
Wes Stewart wrote:
On Thu, 29 Jan 2004 10:00:38 -0600, Cecil Moore wrote: |Wes Stewart wrote: | Sorry, I've taken all of the jabs at this tarbaby that I care to. I | spent a lot of time preparing the paper that I published and it | "reflects reality" as I see it, until proven otherwise. | |What is the name of your paper, Wes? I don't remember you |mentioning it before. All I have seen from your postings is |.pdf files of the work of others. I began this thread with a pointer to: http://www.qsl.net/n7ws/Loaded%20antennas.htm A quick scan of your article produces nothing new. I have already stated multiple times that the magnitude of the current into a coil and the magnitude of the current out of the coil can have any relationship. The magnitude of the current into the coil can be equal, less than, or greater than the current out of the coil depending upon where it is installed in the antenna system. If the coil is installed at a current maximum point, a current maximum will occur in the coil. That's a no-brainer. Exactly what is it that you think you have proven? -- 73, Cecil, W5DXP |
Tdonaly wrote:
Cecil wrote, EZNEC seems to model inductive stubs just fine so I have no reason to distrust it. EZNEC fails to give the same results for an inductive stub Vs a lumped inductive reactance because it doesn't model real-world coils. It will not model Kraus' phase-reversing coil and gives erroneous results when an antenna using phase-reversing coils is modeled. I have the EZNEC files that demonstrate that fact if you would like to have them. Cecil, you can't even give a coherent explanation of how or why Kraus "phase reversing coil" works, or how it relates to Wes' work. I would expect any coil would work between two half-wave dipoles, but maybe not at the frequencies you expect, and certainly not just because Kraus said so. According to Kraus, his phase-reversing coil can be thought of as 1/2WL of wire coiled into an inductance. Ideally, that makes the phase of the current the same on both sides of the coil instead of opposite as it would be if the coil was not there. Tom, do you understand self-resonance? The coil between the two half-wave elements must be self-resonant at the frequency for which the elements are 1/2WL. A 1/2WL stub performs that function perfectly according to EZNEC. But there is *NO* value of inductive reactance in EZNEC that will produce the same effect as that stub. Would you like a copy of those EZNEC files? Would you like for me to post them on my web page? -- 73, Cecil, W5DXP |
On Thu, 29 Jan 2004 12:52:25 -0600, Cecil Moore
wrote: |Wes Stewart wrote: | | On Thu, 29 Jan 2004 10:00:38 -0600, Cecil Moore | wrote: | | |Wes Stewart wrote: | | Sorry, I've taken all of the jabs at this tarbaby that I care to. I | | spent a lot of time preparing the paper that I published and it | | "reflects reality" as I see it, until proven otherwise. | | | |What is the name of your paper, Wes? I don't remember you | |mentioning it before. All I have seen from your postings is | |.pdf files of the work of others. | | I began this thread with a pointer to: | http://www.qsl.net/n7ws/Loaded%20antennas.htm | |A quick scan of your article produces nothing new. Fine. Then this thread is closed. |
Wes Stewart wrote:
wrote: |A quick scan of your article produces nothing new. Fine. Then this thread is closed. It would be nice to know what you think I have said that you are arguing against. It is no surprise that a current maximum point can be located inside a coil. That's probably why W8JI got equal magnitudes of currents at each end of his coil during one of his experiments. Adjust your model until maximum current occurs at the feedpoint and then take a look at the currents in and out of the coil. -- 73, Cecil, W5DXP |
Cecil wrote,
Dan Richardson wrote: wrote: I haven't been paying attention. Obviously The original posting made no assertions and was simply a URL which didn't respond when I tried to access it. The subsequent postings seemed to be concerned with radiation resistance so I didn't even read them. How does radiation resistance affect the loading coil discussion? It has already been proven that EZNEC's lumped circuit model doesn't work for Kraus' real world loading coils. What else is there to say? -- 73, Cecil http://www.qsl.net/w5dxp A lot. Besides, it hasn't been proven, at least not by you, that Kraus' loading coils work the way you seem to think they do. 73, Tom Donaly, KA6RUH |
Cecil wrote,
Wes Stewart wrote: wrote: |A quick scan of your article produces nothing new. Fine. Then this thread is closed. It would be nice to know what you think I have said that you are arguing against. It is no surprise that a current maximum point can be located inside a coil. That's probably why W8JI got equal magnitudes of currents at each end of his coil during one of his experiments. Adjust your model until maximum current occurs at the feedpoint and then take a look at the currents in and out of the coil. -- 73, Cecil, W5DXP I don't think anyone is going to fall for your attempt to make another 500 post rant, Cecil. Adjust the model yourself, if you think that's what it will show, and put the results on your website. 73, Tom Donaly, KA6RUH |
What the whole damn lot of you have forgotten is the electromagnetic
coupling which occurs between the antenna wire sections on either side of the phasing coils, especially when the adjacent wire sections are supposed to be in anti-phase with each other. |
Cecil wrote,
According to Kraus, his phase-reversing coil can be thought of as 1/2WL of wire coiled into an inductance. Ideally, that makes the phase of the current the same on both sides of the coil instead of opposite as it would be if the coil was not there. Tom, do you understand self-resonance? The coil between the two half-wave elements must be self-resonant at the frequency for which the elements are 1/2WL. A 1/2WL stub performs that function perfectly according to EZNEC. But there is *NO* value of inductive reactance in EZNEC that will produce the same effect as that stub. Would you like a copy of those EZNEC files? Would you like for me to post them on my web page? -- 73, Cecil, W5DXP If Kraus really believes that, he's as ignorant as you are. A stub is not the same as a lumped-component tank circuit. Do the math. By the way, Cecil, I'm surprised at you. Have you tried *EVERY* value of inductive reactance in EZNEC? I suspect, though, that the reason there is no value of inductive reactance that will do what a stub does at the frequency of interest is that it's impossible due to the principle of conservation of charge. If you can figure out why I think that is true, then you get a star by your name. 73, Tom Donaly, KA6RUH (PS Take your antenna, with its coil, apart, measure the resonant frequency of each part, and get back to us with your results.) |
Tdonaly wrote:
Besides, it hasn't been proven, at least not by you, that Kraus' loading coils work the way you seem to think they do. Kraus' phase-reversing coils work the way he says they do. A high impedance trap blocks current if it is looking into a low impedance because it is a high impedance. But if it is looking into a high impedance, like a 1/2WL element, it simply reverses the phase of the current, like a quarter-wave shorted series stub. Would you like me to send you the EZNEC files that demonstrate the phase reversal using stubs or multiple sources? -- 73, Cecil, W5DXP |
Tdonaly wrote:
Adjust the model yourself, if you think that's what it will show, and put the results on your website. Unfortunately, I don't have the modeling software that Wes is using. And I have already demonstrated the effect using inductive loading stubs modeled with EZNEC. Reg has already said that real-world coils with Ls, Cs, & Rs, can be treated as transmission lines. Rhea's paper on a new solenoid model agrees with Reg. Have you ever seen a transmission line less than 1/2WL long where the current-in is equal to the current-out when there are standing waves present? Even in a transmission line without reflections, the current-in is never equal to the current-out in magnitude and phase except for lossless lines at the N*wavelength points. Most of this stuff is common sense for anyone who thinks that reality should dictate the model, not vice versa. Einstein once said that all our models are flawed. -- 73, Cecil, W5DXP |
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