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Richard Clark wrote in message ... On Tue, 12 Oct 2004 15:44:02 -0700, "Chuck" wrote: Nonsense! I have made the assertion - and I continue to do so - that minninec and NEC based programs cannot model my design simply from their inability to simulate a virtual bi-directional coaxial phasing/delay line. A "virtual bi-directional coaxial phasing/delay line." That's a good one. Very inventive. Either you're remarkably ignorant, or you've made a failed attempt at being clever... which is it? I didn't make up that silly bafflegab, you did. As those things go, it was pretty good. Your reply is most revealing as to your ignorance in this regard! Hi Chuck, Hi, Richard, It may be regarded as ignorance, It may be regarded as ignorance when one questions a simple term... especially when your claim is unsubstantiated Not in the minds of users, or to those who made confirmation indepently. and demands that your proof is available only through a privileged knowledge. Knowledge comes from experience... anyone can achieve it if they truly had the desire. Getting off one's butt and performing experiments works wonders in this regard... :) However being ignorant is not the same as being stupid. Agreed. The onus is upon you to show (resolve ignorance or exhibit it in your own thinking - there are no third options) how your claim is substantial - testimonial is insufficient. Let me suggest, the onus is on you to prove the claim is without substance since you are the one making the allegation. The design is time tested, and I tire of closed minds. If some folks wish to remain ignorant in this regard, it's their loss, for they only deny themselves a better way. I have more important concerns in my life do deal with now. 73, Chuck, WA7RAI 73's Richard Clark, KB7QHC |
Wes Stewart wrote in message ... [snip] I'm curious. I don't believe that's possible... |
On Wed, 13 Oct 2004 17:14:47 -0700, "Chuck"
wrote: The onus is upon you to show (resolve ignorance or exhibit it in your own thinking - there are no third options) how your claim is substantial - testimonial is insufficient. Let me suggest, the onus is on you to prove the claim is without substance Hi Chuck, That is about as funny as when Art appeared here proclaiming the marvels of his new invention - and then telling us it was our responsibility to prove his claims. Can you guess how many years ago that was? I'm afraid you are in line behind cfa claims, eh claims, fractal claims and the notable efficiency per unit length claims. But as you have more important things to do, one wonders why you spend so much time with these trivial issues? 73's Richard Clark, KB7QHC |
On Wed, 13 Oct 2004 09:37:58 -0400, "J. Mc Laughlin"
wrote: Good reading. 73 Mac N8TT Hi Mac, I stopped after the obvious mis-application of the term end-fire. I am spending 12 hour days in the field registering new voters - 280 today - and this "patent" clearly exhibits the pay-as-you-go mentality of the PTO. In the field of financial planning this would be called churning accounts. 73's Richard Clark, KB7QHC |
Roy Lewallen wrote in message ... ...pirated copy of EZNEC. That is an absolute lie! My disk is an original - with a large, black, bold, italicized EZNEC at the top of its label - and the party from whom I acquired it, gave it to me with your full knowledge and approval. I can only assume this lie is an egregious and deliberate attempt on your part to defame. I will not discuss this further in public. I made Chuck an offer a while back, as follows: That if he has the Raibeam tested at a certified antenna range and the results show a free-space gain of at least 5.5 dBd (7.65 dBi) with simultaneous 25 dB or greater f/b ratio, I'll pay the test fee. This is performance less than he claims and less than he claims his model shows. But so far he hasn't taken me up on the offer. It's rather moot, now that I am no longer in business. However, If it's your desire to spend money to embarrass yourself, I won't argue. There were two reasons why I let your offer slide. First, I was unaware of any testing facilities in my area, and second, I was struggling to meet customer demand and could not justify spending the time to develop a unit for UHF, since it was my understanding that most testing facilities could not accommodate frequencies lower than 100 MHz or so. I've since learned that the US Army testing range at Fort Huachuca in Tucson, AZ is open to civilian testing, and they can accommodate frequencies as low as 50 MHz. My wife will finish her chemotherapy and radiation treatments in March, and since she is quite ill, I cannot foresee my being available until after that time. Allowing say 30 days or so for me to prepare an antenna, I invite you to make the arrangements in Tucson - say April - May, 2005 or so - and I will be more than happy to join you there. Is this agreeable? Chuck, WA7RAI |
Richard Clark wrote in message ... On Wed, 13 Oct 2004 17:14:47 -0700, "Chuck" wrote: The onus is upon you to show (resolve ignorance or exhibit it in your own thinking - there are no third options) how your claim is substantial - testimonial is insufficient. Let me suggest, the onus is on you to prove the claim is without substance Hi Chuck, That is about as funny as when Art appeared here proclaiming the marvels of his new invention - and then telling us it was our responsibility to prove his claims. Can you guess how many years ago that was? Hi Richard, It is my opinion - and only an opinion - that Art's antenna did achieve critical coupling... and perhaps yet another case where the model failed to agree with empirical observations... I'm afraid you are in line behind cfa claims, eh claims, fractal claims and the notable efficiency per unit length claims. But as you have more important things to do, one wonders why you spend so much time with these trivial issues? A few hours a month or less is 'much' time? Surely you jest... :) In any case, since you have no first- hand experience with my design, all you can offer is mere opinion - the antithesis of fact. Since my design can stand on its established record, the onus is on you to provide something of real substance - say, empirical data - to support your opinion. 73, Chuck, WA7RAI 73's Richard Clark, KB7QHC |
Chuck wrote:
Roy Lewallen wrote in message ... ...pirated copy of EZNEC. That is an absolute lie! My disk is an original - with a large, black, bold, italicized EZNEC at the top of its label - and the party from whom I acquired it, gave it to me with your full knowledge and approval. I can only assume this lie is an egregious and deliberate attempt on your part to defame. I will not discuss this further in public. I'll take your word for it, and apologize. You had claimed long ago that the program was given or sold to you, but for reasons of your own you would never tell me from whom. (Although I certainaly approve of such transfers, I never gained knowledge of whom the transfer was from.) In my posting of Sept. 26, 1997 on this newsgroup, I said: I don't generally give support to someone who's not a registered user, but in this case I guess it's necessary. (You still haven't sent me the name of the person who gave you the program, so I can transfer the ownership to you from him.) Because you never furnished that information, I assumed that you had acquired it illicitly. If you'll email me the name or call of the person from which you acquired it and the amount you paid, I'll promptly send you a full refund, in accordance with my guarantee. You're obviously not a satisfied user. I made Chuck an offer a while back, as follows: That if he has the Raibeam tested at a certified antenna range and the results show a free-space gain of at least 5.5 dBd (7.65 dBi) with simultaneous 25 dB or greater f/b ratio, I'll pay the test fee. This is performance less than he claims and less than he claims his model shows. But so far he hasn't taken me up on the offer. It's rather moot, now that I am no longer in business. However, If it's your desire to spend money to embarrass yourself, I won't argue. There were two reasons why I let your offer slide. First, I was unaware of any testing facilities in my area, and second, I was struggling to meet customer demand and could not justify spending the time to develop a unit for UHF, since it was my understanding that most testing facilities could not accommodate frequencies lower than 100 MHz or so. I've since learned that the US Army testing range at Fort Huachuca in Tucson, AZ is open to civilian testing, and they can accommodate frequencies as low as 50 MHz. My wife will finish her chemotherapy and radiation treatments in March, and since she is quite ill, I cannot foresee my being available until after that time. Allowing say 30 days or so for me to prepare an antenna, I invite you to make the arrangements in Tucson - say April - May, 2005 or so - and I will be more than happy to join you there. Is this agreeable? No, you'll have to make the arrangements. Determine the cost of the test. I suggest that we find someone who is willing and we both can trust to whom I'll send the money the test will cost, as proof of my willingness and ability to pay the test fee if the antenna meets the criteria. Let me know when the test is to be done, and I'll come down and observe. The person who pays will have the legal right to make the results public. I agree in advance to do so if I pay; I expect you to do likewise. Roy Lewallen, W7EL |
W7EL wrote:
I made Chuck an offer a while back, as follows: That if he has the Raibeam tested at a certified antenna range and the results show a free-space gain of at least 5.5 dBd (7.65 dBi) with simultaneous 25 dB or greater f/b ratio, I'll pay the test fee. This is performance less than he claims and less than he claims his model shows. But so far he hasn't taken me up on the offer. Ken, K7GCO got bunch of RAIbeams and put them up, wrote glowing review for 73 Mag. He was impressed with the performance and wanted to figure out why is it so. He very carefully inserted dimensions into EZNEC model and could not get agreement. He had to go down to 48. 5 MHz in EZNEC to obtain similar pattern and parameters as real antenna resonant at 51.25 MHz. So, maybe modeling doesn't "see" the dual driven elements and critical coupling well? It is amusing to see the "experts" defending unmistakability of software (loading coil case etc.) Yuri, K3BU.us can we all get alone? |
...pirated copy of EZNEC.
That is an absolute lie! My disk is an original - with a large, black, bold, italicized EZNEC at the top of its label - and the party from whom I acquired it, gave it to me with your full knowledge and approval. I can only assume this lie is an egregious and deliberate attempt on your part to defame. I will not discuss this further in public. I made Chuck an offer a while back, as follows: That if he has the Raibeam tested at a certified antenna range and the results show a free-space gain of at least 5.5 dBd (7.65 dBi) with simultaneous 25 dB or greater f/b ratio, I'll pay the test fee. This is performance less than he claims and less than he claims his model shows. But so far he hasn't taken me up on the offer. It's rather moot, now that I am no longer in business. However, If it's your desire to spend money to embarrass yourself, I won't argue. There were two reasons why I let your offer slide. First, I was unaware of any testing facilities in my area, and second, I was struggling to meet customer demand and could not justify spending the time to develop a unit for UHF, since it was my understanding that most testing facilities could not accommodate frequencies lower than 100 MHz or so. I've since learned that the US Army testing range at Fort Huachuca in Tucson, AZ is open to civilian testing, and they can accommodate frequencies as low as 50 MHz. My wife will finish her chemotherapy and radiation treatments in March, and since she is quite ill, I cannot foresee my being available until after that time. Allowing say 30 days or so for me to prepare an antenna, I invite you to make the arrangements in Tucson - say April - May, 2005 or so - and I will be more than happy to join you there. Is this agreeable? Chuck, WA7RAI Chuck, I am sorry to hear that another individual here is allegedly making false statements. I, personally, wish you well, and I am very sorry to hear about your wife's illness, and wish her a speedy recovery. I appreciate that you are a professional, and as one professional to another, I want to point out that you are an honorable person. I am of the opinion that we should all show you the proper respect. I am sorry if that is not, apparently, being shown by a very few. Sierra Vista is a beautiful place, and the Fort has some cool antenna stuff. They might go down below 50 MHz, BTW. My best wishes to you; been a long time. 73, Chip N1IR |
Yuri Blanarovich wrote:
Ken, K7GCO got bunch of RAIbeams and put them up, wrote glowing review for 73 Mag. He was impressed with the performance and wanted to figure out why is it so. He very carefully inserted dimensions into EZNEC model and could not get agreement. He had to go down to 48. 5 MHz in EZNEC to obtain similar pattern and parameters as real antenna resonant at 51.25 MHz. So, maybe modeling doesn't "see" the dual driven elements and critical coupling well? It is amusing to see the "experts" defending unmistakability of software (loading coil case etc.) I'm sure you're glad, as I am, that Chuck has finally accepted my offer and agreed to have a real, professional test done, after something like 8 years. The results of the test should put to rest any speculation about this issue. I'm looking forward to the test and seeing the test results. I get feedback from some of my professional customers who have the capability to test the antennas they analyze with EZNEC. They report very good agreement between analysis and measurement. Of course, most of them are real pros in both modeling and measurement. Given the choice of believing their results or Ken's and Chuck's, I go for theirs. Even though you might not consider those folks to be "experts", I do. But by all means, let's look at the test results -- unless you believe that "critical coupling" results in radiation that conventional test ranges can't detect but hams can. . . Roy Lewallen, W7EL |
On Thu, 14 Oct 2004 15:33:23 -0700, Roy Lewallen
wrote: |Chuck wrote: | Roy Lewallen wrote in message | ... | |...pirated copy of EZNEC. | | | That is an absolute lie! | | My disk is an original - with a large, black, | bold, italicized EZNEC at the top of its | label - and the party from whom I acquired | it, gave it to me with your full knowledge | and approval. I can only assume this lie is | an egregious and deliberate attempt on | your part to defame. I will not discuss this | further in public. | |I'll take your word for it, and apologize. You had claimed long ago that |the program was given or sold to you, but for reasons of your own you |would never tell me from whom. (Although I certainaly approve of such |transfers, I never gained knowledge of whom the transfer was from.) In |my posting of Sept. 26, 1997 on this newsgroup, I said: | | I don't generally give support to someone who's not a registered user, | but in this case I guess it's necessary. (You still haven't sent me | the name of the person who gave you the program, so I can transfer the | ownership to you from him.) | |Because you never furnished that information, I assumed that you had |acquired it illicitly. | |If you'll email me the name or call of the person from which you |acquired it and the amount you paid, I'll promptly send you a full |refund, in accordance with my guarantee. You're obviously not a |satisfied user. | | | | I made Chuck an offer a while back, as follows: That if he has the | Raibeam tested at a certified antenna range and the results show a | free-space gain of at least 5.5 dBd (7.65 dBi) with simultaneous 25 dB | or greater f/b ratio, I'll pay the test fee. This is performance less | than he claims and less than he claims his model shows. But so far he | hasn't taken me up on the offer. | | | | It's rather moot, now that I am no longer in | business. However, If it's your desire to | spend money to embarrass yourself, I | won't argue. | | There were two reasons why I let your offer | slide. First, I was unaware of any testing | facilities in my area, and second, I was | struggling to meet customer demand and | could not justify spending the time to | develop a unit for UHF, since it was my | understanding that most testing facilities | could not accommodate frequencies lower | than 100 MHz or so. | | I've since learned that the US Army testing | range at Fort Huachuca in Tucson, AZ is | open to civilian testing, and they can | accommodate frequencies as low as 50 | MHz. Fort Huachuca is not located in Tucson, it is located at Sierra Vista, AZ, approximately 90 miles SE of Tucson. Some of the capabilities are listed he http://www.epg.army.mil/Test_Beds/ATF.htm As an aside, I have tested under the ARC range and have been to the top of the "Red Tower" just to look around. Quite a view! I've seen photos of an M1-A1 tank mounted on the positioner of the "Compact" range. Unfortunately, when I was there five years ago, a lot of the equipment associated with the compact range appeared to be in disrepair. I suspect that you will have a hard time getting testing done here as security is a big issue. But I could be wrong. | | My wife will finish her chemotherapy and | radiation treatments in March, and since | she is quite ill, I cannot foresee my being | available until after that time. | | Allowing say 30 days or so for me to | prepare an antenna, I invite you to make | the arrangements in Tucson - say April - | May, 2005 or so - and I will be more | than happy to join you there. | | Is this agreeable? | |No, you'll have to make the arrangements. | |Determine the cost of the test. I suggest that we find someone who is |willing and we both can trust to whom I'll send the money the test will |cost, as proof of my willingness and ability to pay the test fee if the |antenna meets the criteria. Let me know when the test is to be done, and |I'll come down and observe. The person who pays will have the legal |right to make the results public. I agree in advance to do so if I pay; |I expect you to do likewise. | |Roy Lewallen, W7EL |
I get feedback from some of my professional customers who have the capability to test the antennas they analyze with EZNEC. They report very good agreement between analysis and measurement. Of course, most of them are real pros in both modeling and measurement. Given the choice of believing their results or Ken's and Chuck's, I go for theirs. Even though you might not consider those folks to be "experts", I do. Maybe there are cases when things don't play as figured? Maybe would be of interest for software author to find out, and if there is a glichand to find the way to accomodate it? Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it? Experts said one time that she's flat. But by all means, let's look at the test results -- unless you believe that "critical coupling" results in radiation that conventional test ranges can't detect but hams can. . . Roy Lewallen, W7EL Here we go again, W8JI snotty style? I just mentioned what K7GCO found, in hope that it might shine some light at the subject and arouse some curiosity about disagreement. If it is inconvenient, than I am sorry to butt in here. I have no intentions to get engaged in ****ing contest. Right now I am too busy with new ocean front QTH next to 170 acre Rhombic antenna farm, DR1 design and business that brings livelihood. When I get more time, I will get back to work on antennas, setup test range (across salt water bay) and get into paper models vs. real ones. Peace! Yuri, K3BU.us |
Yuri Blanarovich wrote:
Maybe there are cases when things don't play as figured? Maybe would be of interest for software author to find out, and if there is a glichand to find the way to accomodate it? Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it? Experts said one time that she's flat. EZNEC v. 4.0 has a convenient helix creation feature, which allows the user to quickly make a wire model of an inductor. An inductor modeled in this way will show a current distribution very close to that of a real inductor. There are two cautions, however. One is that EZNEC programs prior to v. 4.0.7 had a bug that would create incorrectly sized wire (when creating a helix or loop) if wire diameter was specified as AWG rather than numerical diameter. So be sure to update your program to the latest version by downloading and installing the latest update from http://eznec.com/ez40updates. (You've said you don't read the manual, so you probably aren't aware of these free updates.) The second caution is that turns should ideally be spaced at least several wire diameters apart. I have, however, seen good results with spacings down to one wire diameter. At that spacing, though, EZNEC will overestimate the Q somewhat (that is, underestimate the loss) because it doesn't account for proximity effect. . . . Roy Lewallen, W7EL |
"Roy Lewallen" wrote in message ... Yuri Blanarovich wrote: Ken, K7GCO got bunch of RAIbeams and put them up, wrote glowing review for 73 Mag. He was impressed with the performance and wanted to figure out why is it so. He very carefully inserted dimensions into EZNEC model and could not get agreement. He had to go down to 48. 5 MHz in EZNEC to obtain similar pattern and parameters as real antenna resonant at 51.25 MHz. So, maybe modeling doesn't "see" the dual driven elements and critical coupling well? It is amusing to see the "experts" defending unmistakability of software (loading coil case etc.) I'm sure you're glad, as I am, that Chuck has finally accepted my offer and agreed to have a real, professional test done, after something like 8 years. Where is this "acceptance" stated ? Chuck made a suggestion and then you made a counter suggestion the last time I read the newsgroup ! I think it is to early for you Roy to be "amused" at the technical ability of other hams or experimenters in the hobby. Could you start off being humble regarding efforts of other amateurs ? Art The results of the test should put to rest any speculation about this issue. I'm looking forward to the test and seeing the test results. I get feedback from some of my professional customers who have the capability to test the antennas they analyze with EZNEC. They report very good agreement between analysis and measurement. Of course, most of them are real pros in both modeling and measurement. Given the choice of believing their results or Ken's and Chuck's, I go for theirs. Even though you might not consider those folks to be "experts", I do. But by all means, let's look at the test results -- unless you believe that "critical coupling" results in radiation that conventional test ranges can't detect but hams can. . . Roy Lewallen, W7EL |
On Thu, 14 Oct 2004 14:56:15 -0700, "Chuck"
wrote: the onus is on you to provide something Hi Chuck, Like I said, this has been a hoot. 73's Richard Clark, KB7QHC |
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Richard Clark wrote:
On 15 Oct 2004 01:19:49 GMT, oUsama (Yuri Blanarovich) wrote: Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it? Hi Yuri, From Roy's description, you published at your web site how to do this nearly a year ago. Have you lost that page? 73's Richard Clark, KB7QHC What is a "current drop?" 73, Tom Donaly, KA6RUH |
Yuri Blanarovich, K3BU wrote:
"Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it?" Current drop across a coil is E/Z where Z is complex. If a reflection is involved in the antenna, there are multiple Es involved, perhaps. Growing or shrinking current through a coil, generates a voltage which opposes current in the coil. Because of its opposing direction it is called "counter emf". The change in current in the coil generates the counter emf. A steady d-c current in a coil generates no emf. A given length of wire has much greater counter emf when coiled than when stretched out straight. We say it has more "inductance". It`s because fields from close-wound turns intercouple. With 3 turns closewound in a coil, 3 times the lines of force cut 3 turns, so 9 times the counter emf is generated. As a first approximation, the inductance varies as the square of the number of turns. Opposition of counter emf in a coil delays the rise of current in a coil from the phase of an a-c voltage. In a perfect coil with no resistance, the delay is 90-degrees or 1/4-cycle. Resistance, useful or useless, reducees the current delay. Due only to the L/R ratio, the phase delay imposed by a coil can vary from 90-degrees down to zero. I did a web search on "r.r.a.a" which produced 590 hits. One of these was something posted by Roy Lewallen entitled "Inductor Operation". Roy had measured phase delay in a loading coil. If I understood Roy, he found no phase delay in an antenna loading coil. In my opinion, he should find delay even in a coil feeding a dummy load, especially if the coil is large as compared with the dummy load. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote:
Yuri Blanarovich, K3BU wrote: "Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it?" Current drop across a coil is E/Z where Z is complex. If a reflection is involved in the antenna, there are multiple Es involved, perhaps. Growing or shrinking current through a coil, generates a voltage which opposes current in the coil. Because of its opposing direction it is called "counter emf". The change in current in the coil generates the counter emf. A steady d-c current in a coil generates no emf. A given length of wire has much greater counter emf when coiled than when stretched out straight. We say it has more "inductance". It`s because fields from close-wound turns intercouple. With 3 turns closewound in a coil, 3 times the lines of force cut 3 turns, so 9 times the counter emf is generated. As a first approximation, the inductance varies as the square of the number of turns. Opposition of counter emf in a coil delays the rise of current in a coil from the phase of an a-c voltage. In a perfect coil with no resistance, the delay is 90-degrees or 1/4-cycle. Resistance, useful or useless, reducees the current delay. Due only to the L/R ratio, the phase delay imposed by a coil can vary from 90-degrees down to zero. I did a web search on "r.r.a.a" which produced 590 hits. One of these was something posted by Roy Lewallen entitled "Inductor Operation". Roy had measured phase delay in a loading coil. If I understood Roy, he found no phase delay in an antenna loading coil. In my opinion, he should find delay even in a coil feeding a dummy load, especially if the coil is large as compared with the dummy load. Best regards, Richard Harrison, KB5WZI It might be profitable for you to actually try the measurement. Like Roy, I also find no delay *across* a physically small coil. The coil does cause a delay between current and voltage, and as theory would indicate, that delay (and V/I phase relationship) appears everywhere in the series circuit, rather than locally across the coil. But, as I believe Reg and others have suggested previously, as the coil begins to take on dimensions that are a larger faction of a wavelength, propagation delays begin to produce additional effects, manifested in particular by the standing wave profile. In physically small, inductively large coils, I can find no propagation delay. This is consistent with the report on W8JI's web page. However I think it's reasonable to say that as the coil starts to become physically large, it begins to produce observable delays. These delays appear to be greater than one would expect for a straight conductor of the same length. Perhaps someone here can explain why that might be, but I am as yet unable to. I suspect that it's because as the coupling between turns is reduced, the coil begins to look less like an inductor, and more like a compact length of transmission line arranged in the shape of a helix. 73, Jim AC6XG |
Jim Kelley wrote:
"The coil does cause a delay between current and voltage, and as theory would indicate that delay (and V/I phase relationswhip) appears everywhere in the series circuit." As an example, place a perfect coil and a perfect resistor in a series combination. The voltage drop across the resistor is exactly in-phase with the current throuigh the resistor. It is independent of the phase of the circuit current. The voltage drop across the coil precedes the current through the coil by 90-degrees. The phase of current in the series circuit with respect to the voltage applied to the circuit is determined with vector math. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote:
Yuri Blanarovich, K3BU wrote: "Have you figured out how to model loading coil of particular inductance and physical size to reflect the real current drop across it?" Current drop across a coil is E/Z where Z is complex. If a reflection is involved in the antenna, there are multiple Es involved, perhaps. (the rest snipped) Best regards, Richard Harrison, KB5WZI Richard, there is no such thing as a "current drop." 73, Tom Donaly, KA6RUH |
Tom Donaly, KA6RUH wrote:
"Richard, there is no such thing as a "current drop." This is where i came in almost a year ago. Yuri may havr posted Fig 9-22 from page 9-15 of the 1994 edition of ON4UN`s "Low-Band DXing". There are base loading, center loading, and continuous loading examples of short vertical antennas, and their current distributions. In every case, the currents at the two ends of the coil are different. The impedance of an antenna is a function of position along the antenna. There is radiation from an antenna so not only is the impedance along an antenna a variable, but the the transmit power level power level along an antenna is a variable, too. These variables ensure a difference between the current into and out of a loading coil. Current is high where impedance is low, and current is high where power is high. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote:
Tom Donaly, KA6RUH wrote: "Richard, there is no such thing as a "current drop." This is where i came in almost a year ago. Yuri may havr posted Fig 9-22 from page 9-15 of the 1994 edition of ON4UN`s "Low-Band DXing". There are base loading, center loading, and continuous loading examples of short vertical antennas, and their current distributions. In every case, the currents at the two ends of the coil are different. The impedance of an antenna is a function of position along the antenna. There is radiation from an antenna so not only is the impedance along an antenna a variable, but the the transmit power level power level along an antenna is a variable, too. These variables ensure a difference between the current into and out of a loading coil. Current is high where impedance is low, and current is high where power is high. Best regards, Richard Harrison, KB5WZI Let me repeat, for those who might be tempted to use the term "current drop" in their casual conversation, there is no such thing as a "current drop." There can be variations in current in transmission lines, antennas, etc., but those are not "current drops." I'm surprised at you and Yuri, Richard. You two will have the CBers laughing at us. 73, Tom Donaly, KA6RUH |
Richard Harrison wrote:
Tom Donaly, KA6RUH wrote: "Richard, there is no such thing as a "current drop." This is where i came in almost a year ago. Yuri may havr posted Fig 9-22 from page 9-15 of the 1994 edition of ON4UN`s "Low-Band DXing". There are base loading, center loading, and continuous loading examples of short vertical antennas, and their current distributions. In every case, the currents at the two ends of the coil are different. Unfortunately those diagrams are misleading. They draw a current profile against a scale of electrical height, which makes it look as if there is a significant change in current along the length of the coil. The current profile can only be correctly drawn against a scale of *physical* height. Then the error goes away, and the current is seen to be uniform through the coil. What does change is the shape of the current distribution above and below the coil. All of ON4UN's math is good, and if you follow that instead of the pictures, you will find that the current through the coil is always assumed to be constant. In other words, he assumes an ideal inductor. The text and math shown that ON4UN actually understands the situation perfectly. I don't believe for a moment that he expected those diagrams to be so fundamentally misinterpreted. The impedance of an antenna is a function of position along the antenna. There is radiation from an antenna so not only is the impedance along an antenna a variable, but the the transmit power level power level along an antenna is a variable, too. These variables ensure a difference between the current into and out of a loading coil. No: there is no change in current through a coil that is physically tiny, and doesn't have any capacitive coupling with the rest of the antenna. All the changes occur above and below the coil. Any deviation from equal currents in and out has to be caused by the physical size of any real coil being non-zero. Then, even a physically small coil will behave like a very short section of helical monopole antenna. It is radiating an EM field, so there must also be some variation in current along its length. (The extreme case of a long coil is the fully helical whip, where the antenna and the coil are one and the same.) There is also a lot of loose talk about "phase variation" due to an ideal inductor. This is NOT a phase variation in the current from end to end! What changes is the phase of the voltage between the input and the output. At each end you are measuring the phase of the voltage, *relative* to the phase of the current which does *not* change. Now someone is going to come right back at me, talking about "real life" this and "practical" that. But if someone does not understand how an inductor is even *meant* to behave, all their practical knowledge is built on sand - they may know lots of stuff, but they don't truly understand it. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Now someone is going to come right back at me, talking about "real life" this and "practical" that. But if someone does not understand how an inductor is even *meant* to behave, all their practical knowledge is built on sand - they may know lots of stuff, but they don't truly understand it. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek Here we go again! Where have you been Ian? Applying DC current behaviour in the inductor to standing wave RF current situation in the antenna, Eh? In case you missed previous exchanges http://www.k3bu.us/loadingcoils.htm That is in practice and (right) theory. Cecil showed (hairpinned) model in EZNEC. And that ain't no lie! 73 and keep your readers informed properly :-) Yuri, K3BU.us www.computeradio.us home of "Dream Radio One" |
Yuri Blanarovich wrote:
Now someone is going to come right back at me, talking about "real life" this and "practical" that. But if someone does not understand how an inductor is even *meant* to behave, all their practical knowledge is built on sand - they may know lots of stuff, but they don't truly understand it. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek Here we go again! Where have you been Ian? Applying DC current behaviour in the inductor to standing wave RF current situation in the antenna, Eh? No. Step 1: I am starting from the fundamental AC current behaviour of an ideal inductor. The phases of the voltages at its opposite ends are different; but at every given instant, the currents at its opposite ends are equal and in phase. 2. I am expecting that ideal inductor to behave in exactly the same way when used as a loading device in an antenna - which in fact it does, because exactly the same laws of physics apply. 3. Then I'm in a good place to start to think how that behaviour will change for a real inductor that has both physical size and capacitive coupling to the rest of the antenna. In case you missed previous exchanges http://www.k3bu.us/loadingcoils.htm That is in practice and (right) theory. Cecil showed (hairpinned) model in EZNEC. And that ain't no lie! 73 and keep your readers informed properly :-) Oh, I shall, I shall... I'll begin by pointing out the obvious: an ideal inductor, a honkin' great length of Airdux and a shorted parallel stub are three physically different objects. Each one is a different kind of loading device, with different effects when inserted into an antenna - and none of those loading devices is the same as the length of real antenna that it's claimed to "replace". The flaw in your viewpoint is that you are expecting a loading device to "replace" too many of the properties of a genuine piece of antenna. It actually replaces very few of them, and each different loading device does it in a different way. Cecil's stub behaves exactly as expected - for a stub. But a shorted transmission line is not an inductor - it has some of the properties of an inductor, but not all of them. In particular, the currents at its two terminals can be unequal, because a stub can carry common-mode current and radiate and EM field, which an inductor cannot. Therefore the stub example is irrelevant to a discussion that is trying to compare various inductors. The same is true of different types of inductors. The ideal inductor and the Airdux are both loading devices - they do not completely replace the missing piece of the antenna. They replace it in one respect only (making the feedpoint reactance equal to zero) but all other things about the loaded antenna are *different* from the full-sized antenna. In particular, the current and voltage distributions above and below the load are different from full size, and so of course is the feedpoint resistance. I cannot explain every detail of Barry Boothe's measurements, but I know for certain that the true explanation is the one that obeys all the laws of physics and circuit theory, down to the last detail. What you have, Yuri, is an "explanation" that uses those laws in some parts, but twists or ignores them in others. That cannot possibly be correct. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Roy Lewallen wrote in message ... Chuck wrote: . . . That said, I take exception with your statement regarding the bi-directionality of the simulated coaxial transmission lines in available NEC(n) engines. Their simulations are uni-directional - from the input to the load, but not in reverse. That is patently false, and can be easily demonstrated. The transmission line model in NEC (and EZNEC) is a linear network which is completely bidirectional. Roy, Linear, yes... bi-directional? Not as I see it... and leaves one wondering why NEC3 is available only to government entities and contractors... To confirm your claim, please post a demonstration that confirms energy in the load is flowing into the input. Also, please repost your reply to my post with the header "another lie..." as it did not show up in my newsreader. Thanks, Chuck, WA7RAI |
I cannot explain every detail of Barry Boothe's measurements, but I know for certain that the true explanation is the one that obeys all the laws of physics and circuit theory, down to the last detail. What you have, Yuri, is an "explanation" that uses those laws in some parts, but twists or ignores them in others. That cannot possibly be correct. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek You can't explain reality, but you have good arguments to support your "theory". Now you can plug in solenoid/helix into EZNEC 4.08 and see for yourself what'sup (See my other recent post). We are not claiming that hairpin is exact replacement for lumped inductor, but some properties when inserted into modeling program illustrate better what is really happening (current is NOT equal at both ends of the coil). Take the fricken RF ammeters and stick'em in the coil's ends, you have excellent current probe on your web site. As you can see from W9UCW measurements and my recent example of 10m loaded vertical that there is significant difference in the current across the loading coil (not equal) and lower you go on frequency when antenna gets short relative to wavelength used, the more pronounced the effect is. Significance? As ON4UN points out, efficiency is proportional to the area under the current curve, that is important for loaded antenna designers, and if they understood this, we would not have the flood of "magical" wrongly loaded, shortened antennas (like Vincent/UoRI "patented" crap). Yuri, K3BU.us just another "dumb" ham |
Ian White, G3SEK wrote:
"The phases of the voltages at its (ideal inductor) ends are different, but at every given instant, the currents at its opposite ends are equal and in phase." When an inductor is placed in a too short standing-wave antenna to correct its power factor, the volts, amps, and impedance at every point on the antenna result from superposition. In general, they vary from end to end. The impedance at any point results from a wave traveling from the feedpoint and a reflected wave from the open-circuit at the tip of the antenna. The reflected wave travels back toward the feedpoint. These waves combine to produce a standing-wave pattern on the antenna much as would be produced on a transmission line. In a standing-wave antenna, such as Yuri has used as an example, of a coil loaded vertical, the impedance is high and the current is insignificant at the open-circuit antenna tip. The impedance is low and the current is high back 90-degrees from the antenna tip. One end of the standing-wave, coil-loaded antenna is fed by its capacitance to the outside world. The other end is fed by its connection to the generator. There is no inherent balance in the feed to the antenna or a loading coil contained within the antenna. A balanced feed to an ideal coil may result in the same current into and out, but an unbalanced feed to a coil will likely result in different currents in and out. Certainly the same power in and out of a coil will produce differing volts and amps to comply with differing impedances at the input and output. The extreme example comes from continuous loading. The entire antenna is a solenoid or coil of wire. The impedance at the tip is very high. At its feedpoint, the impedance is low. The current in the coil tapers from one end to the other. Adding conductors to either or both ends of the coil changes the current but does not usually eliminate current taper in the coil. Best regards, Richard Harrison, KB5WZI |
Sorry, Chuck, I can't thing of one reason why I should accommodate you.
Roy Lewallen, W7EL Chuck wrote: Roy, Linear, yes... bi-directional? Not as I see it... and leaves one wondering why NEC3 is available only to government entities and contractors... To confirm your claim, please post a demonstration that confirms energy in the load is flowing into the input. Also, please repost your reply to my post with the header "another lie..." as it did not show up in my newsreader. Thanks, Chuck, WA7RAI |
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You claim to be a science minded person, yet you choose to accept theoretical results over contradicting empirical data, and do so, without even an iota of curiosity. That is not science, it's closed-minded silliness! Equally as silly, is your raising such a stink over 1/3 of a dB... which will prove to be your Waterloo. :) 73, Chuck, WA7RAI I'l second that! Very precisely put :-) Yuri |
Roy Lewallen wrote in message ... Sorry, Chuck, I can't thing of one reason why I should accommodate you. Gee, Roy... does this mean you don't want me to know your reply to my acceptance of your challenge? Having second thoughts about this, perhaps? In any event, there's always Google... aside from that, some good person here will post it, I'm sure. Does this also mean that you cannot back up your bi-directional claims with facts? A pity... Chuck, WA7RAI Roy Lewallen, W7EL Chuck wrote: Roy, Linear, yes... bi-directional? Not as I see it... and leaves one wondering why NEC3 is available only to government entities and contractors... To confirm your claim, please post a demonstration that confirms energy in the load is flowing into the input. Also, please repost your reply to my post with the header "another lie..." as it did not show up in my newsreader. Thanks, Chuck, WA7RAI |
Ian, if I ever understood, I have long ago lost track of the raging arguments and consequences. You are quite correct, of course, in your analysis of what goes on in and around a loading coil. But in the face of such rigid minds and attitudes your attempts to convince people of the errors in their ways by simple logic is doomed to failure. A solenoidal coil of wire, a loading coil of any proprtions, can be considered to be a continuously loaded, fat, relatively short, single wire, transmission line. Because of the inductive loading it will have a much higher Zo than a solid cylinder of the same length and diameter. Its inductance per unit length will be that of the coil. Its capacitance per unit length will be largely unchanged. For close-wound turns tt will be the same as the solid cylinder. For spaced turns capacitance will only be slightly reduced and calculable. Zo = Sqrt(L/C) and R is the wire HF resistance including proximity effect. To simplify, for a first approximation R can be neglected and the line becomes loss-less. If the length of coil is long enough then its radiation resistance Rrad may be high enough to be taken into account alongside R. The propagation velocity V = 1/Sqrt(L*C) from which phase-shift per unit length of coil can be calculated. (Phase shift appears to be a sore point in the arguments) If necessary, attenuation per unit length can be calculated from R+Rrad. The properties of this line, the coil, is now amenable to normal transmission line analysis with a fair degree of accuracy. Accuracy is limited by the accuracy of determining coil dimensions. Such things as the increase in overall diameter by wire diameter matter. Input impedance can be calculated from the terminating impedance. The terminating impedance is the remainder of the antenna (another transmission line) but for the purpose of settling arguments arbitrary values can be chosen. The phase shifts relative to feedpoint at each junction along the loaded antenna can be calculated. Some of my programs use the above-described calculating method. But none of them have relative-phase outputs for the simple reason that nobody has yet found any practical use for such useless data and in any case there's usually not enough space on the screen. All phases are relative. I've a feeling arguments have arisen because of confusion about what phases are relative to. You've been arguing about different things and you can't ALL be that stupid. Unfortunately, communication via newsgroups cannot make use of body-language. ;o) ;o) ---- Reg, G4FGQ |
I wouldn't bother responding, but I'm afraid some readers might be
misled by what's being said here. Chuck wrote: Yes Roy, It has been well established that the available NEC engines model extremely well with conventional designs. That is not the issue. Your innuendo regarding 'professional' customers is silly. In my 67 years, have been Chief Engineer of commercial radio and television stations, as well as having designed commercial radio and television stations, including the first all solar powered commercial (5 KW) FM station in the US. You seem to opine that the ability to make measurement's is limited to a only special few. Since none of your customers are producing critically coupled designs, your arguments in this regard are without merit, and IMO, the intent of this post was a failed attempt to reduce my standing. The statement about professional users wasn't meant to be innuendo or any sort of slight, but simple fact. I was referring to the aerospace companies, government agencies, universities, broadcast consultants, international broadcast companies, space agencies, and the like that routinely use EZNEC, and some of whom continue to buy additional copies of the professional versions. (Surely you regard these as professional users?) And they don't tell me (or hardly anyone else) specifically the kinds of antenna they design. Since your antenna is seemingly the only one which is incapable of being modeled (other than ones which can't be modeled for well known and documented reasons), you alone must have the key to the magic involved. The NEC-2 manual is available from the web. It explains in detail how the network model, which is used for transmission lines, is implemented. Surely someone with your extensive professional background is able to read and understand it. You claim to be a science minded person, yet you choose to accept theoretical results over contradicting empirical data, and do so, without even an iota of curiosity. Ah, here we go again. Someone makes claims that contradict known and widely accepted principles. Then the charge is made that anyone who disbelieves is narrow minded and without curiosity, and challenged to disprove the extraordinary assertions. I have no obligation to once more show the validity of accepted science; the evidence is there in abundance for anyone with curiosity to see. It's up to you to back up your extraordinary claims with evidence. All I've seen from you for evidence is a mention of back-yard measurements. This is hardly enough to convince me or any rational person that established physics is wrong. I've even put my money where my mouth is, and offered to pay for a real, objective test of your antenna. That's all you're going to get. That is not science, it's closed-minded silliness! Equally as silly, is your raising such a stink over 1/3 of a dB... which will prove to be your Waterloo. :) And that isn't even worthy of a response. Roy Lewallen, W7EL |
Chuck wrote:
Linear, yes... bi-directional? Not as I see it... and leaves one wondering why NEC3 is available only to government entities and contractors... . . . It's not clear why you have a problem with NEC-3 when it was superceded long ago by more-advanced NEC-4. NEC-4 can be purchased by nearly anyone, as a little web research would have quickly revealed. Yes, even you can buy NEC-4. But alas, it also doesn't take into account magical phenomena. Roy Lewallen, W7EL |
Ian,
The equivalent shunt self-capacitance of a coil obviously affects the magnitude and phase of the current which flows in it. This particularly applies when a high-value loading coil is near to the top of a vertical antenna which is terminated with a very short rod or whip. (The self-capacitance of an isolated coil is calculable and can be easily checked by using one of these small hand-held antenna analysers to measure a coil's self-resonant frequency extremely accurately.) In the extreme case, when there is no whip, the only capacitance across the coil is its own self-capacitance. Yet to behave as a loading coil and draw current up the antenna below it, it is required to have a low impedance. A circuit analysis becomes quite involved. The coil impedance has to be in the form of a series resonance with the length of antenna wire below it. So we have a series resonance in the presence of the coil's shunt capacitance. From ordinary lumped circuit theory the equivalent coil Q drastically falls, a very large voltage appears across the coil, and a very large circulating current flows around the coil and its own self-capacitance. Efficiency goes for a Burton and with a high power transmitter either the coil melts or collapses due to voltage-breakdown between turns. The moral of this story is never to locate a loading coil near the top of an antenna. It also explains why maximum efficiency usually occurs between half-way and 2/3 of the way up. With an exceptionally good ground maximum efficiency occurs with bottom loading. In which case you don't need a coil in the antenna at all. You can include it in the tuner. To see how radiating efficiency of a short or long vertical changes with coil height and how coil loss increases extremely rapidly as the coil nears the top of the antenna, download in a few seconds program LOADCOIL from website below. Its quite safe to use the program - there's no danger of setting the coil on fire. You can slide the coil up and down the antenna from the keyboard and immediately observe how a variety of parameters change. Also copious notes. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Ian White, G3SEK wrote:
"Step 1: I am starting from the fundamental AC current behaviour of an ideal inductor." Good start, but incomplete. Fundamental a-c does not include a standing-wave wehich causes a variation of voltage, current, and impedance along the length of the inductor whether straight or coiled. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote:
Ian White, G3SEK wrote: "Step 1: I am starting from the fundamental AC current behaviour of an ideal inductor." Good start, but incomplete. Fundamental a-c does not include a standing-wave wehich causes a variation of voltage, current, and impedance along the length of the inductor whether straight or coiled. I was going to get back to you about that (but Life intervened), to say that I agree with your entire analysis of standing waves on antennas... except for that one point. We need to be very clear about the difference between an ideal inductor and any practical inductor. An ideal inductor has only one property: inductance. It does not have length, diameter, self-capacitance, parasitic capacitance or any of the extra properties that a practical coil has. Let's ignore those for the moment, and try to understand how an antenna is loaded by pure inductance alone. The behaviour of loading inductANCE does not not involve any variation in current between one terminal of the inductance and the other. It cannot, because that is not one of the properties of inductance - not ever, in any circumstances. With a pure loading inductance, the current profile on the antenna has to fit the constraint that the current immediately above the inductance must be equal to the current immediately below it. In the real-life case this is not necessarily true - but we need to be absolutely clear that any difference in current between the top and bottom of a practical loading coil has to be due to those "extra" properties mentioned above. It is not due to the inductance alone, because inductance alone doesn't do that. Unless we understand this fundamental point about how an antenna is loaded by pure inductance, we have no hope of understanding how real-life loading coils actually behave. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Ian White, G3SEK wrote:
"The behaviour of loading inductANCE does not involve any variation in current between one terminal of the inductance and the other." Yuri has attached a photo in this thread again of an antenna loading coil in action as a psrt of a too-short vertical antenna. RF ammeters are mounted in series, one at the coil top and one at the coil bottom. The lower ammeter clearly shows more current than the upper. That`s exactly as should be expected. The too-short whip above the coil has an impedance consisting of a high capacitive reactance and a few ohms of radiation resistance. It`s the coil`s job to cancel the capacitive reactance so it doesn`t oppose current into the too-short whip. Pure inductance alone can cancel pure capacitive reaxctance. In an antenna loading coil as used in a "Texas Bug Catcher", the coil resides about in the middle of the antenna. The coil has length and current, the two factors which produce radiation. The Bug Catcher is approximately a 90-degree antenna, including the phase delay in the loading coil/. ON4UN shows in Fig 9-22 on page 9-15 of "Low=Band DXing", a center-loading example which may represent the Bug Catcher The current taper shown by ON4UN is similar to that shown by other authors deliberately and unmistakenly. A pure series inductance invokes a phase lag. This would be 90-degrees in a pure inductance but we always have some resistance which reduces the phase lag to less than 90-degrees. In olden times, chokes were often called "retard coils". Best regards, Richard Harrison, KB5WZI |
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