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Coils, why?
Why not:
___ ___ | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___| |___| etc. A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Regards, JS P.S. Excuse the bad ascii graphics ... |
Coils, why?
On Dec 2, 7:09 pm, John Smith wrote:
Why not: ___ ___ | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___| |___| etc. A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Regards, JS P.S. Excuse the bad ascii graphics ... Not a very efficient "coil." Consider what the magnetic fields are from each wire segment. A flat _spiral_ is sometimes used, e.g. by etching it into a PCB, though they are generally not as good as traditional helical or toroidal coils. A stub of transmission line less than a quarter wave long and shorted at the far end looks inductive, too, but at HF it's a pretty inefficient way to get inductance. They're much more useful at UHF and above. |
Coils, why?
K7ITM wrote:
On Dec 2, 7:09 pm, John Smith wrote: Why not: ___ ___ | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___| |___| etc. A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Regards, JS P.S. Excuse the bad ascii graphics ... Not a very efficient "coil." Consider what the magnetic fields are from each wire segment. A flat _spiral_ is sometimes used, e.g. by etching it into a PCB, though they are generally not as good as traditional helical or toroidal coils. A stub of transmission line less than a quarter wave long and shorted at the far end looks inductive, too, but at HF it's a pretty inefficient way to get inductance. They're much more useful at UHF and above. Interesting response. The "major efficiency" you are stating is? 1) Inductance per length of conductor? 2) Space required for inductor? 3) Losses? 4) Other? Regards, JS |
Coils, why?
John Smith wrote:
"The "major efficiency" you are stating is?" Q is the usual statement of inductor efficiency. Libear loading has its advocates. My edition of John Devoldere, ON4UN`s "Low-Band DXing" is from 1994. On page 9-36 is Fig 9-46, Two-Band (80 and 160-m) vertical system using linear loading to bring the antenna to resonance on 160 meters. Best regards, Richard Harrison, KB5WZI |
Coils, why?
Richard Harrison wrote:
John Smith wrote: "The "major efficiency" you are stating is?" Q is the usual statement of inductor efficiency. Libear loading has its advocates. My edition of John Devoldere, ON4UN`s "Low-Band DXing" is from 1994. On page 9-36 is Fig 9-46, Two-Band (80 and 160-m) vertical system using linear loading to bring the antenna to resonance on 160 meters. Best regards, Richard Harrison, KB5WZI Thanks Richard, I will see if I can locate an issue that old. Regards, JS |
Coils, why?
John Smith wrote:
Poor old W8JI has taken quite a beating, it is best to realize if mistakes are made, so should it be, we are only human. However, this individual has prepared some nice pages, he has a nice way of writing which are easy to logically follow. Newbies, if they stumble upon his pages, must surely benefit tremendously. Now, as I have stated, I have no real horse in the particular argument which dominates this group--I simply wish to recognise his good work and give him proper credit. If unknowingly slight men of good intentions we may lose them--NOT a good thing ... http://www.w8ji.com/loading_inductors.htm Warm regards to all, JS |
Coils, why?
"John Smith" wrote in message ... Why not: ___ ___ | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___| |___| etc. A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Regards, JS P.S. Excuse the bad ascii graphics ... I tried Linear Loading with a 10-meter Mobile antenna - just to try it out. If I recall, the performance was about the same as a coil-loaded antenna. The reason I like coils is that they fit nicely inside (or outside) a piece of PVC pipe, and makes antenna-making easier. W4PMJ |
Coils, why?
John Smith wrote:
A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Looks like linear loading to me. -- 73, Cecil http://www.w5dxp.com |
Coils, why?
Cecil Moore wrote:
John Smith wrote: A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Looks like linear loading to me. Hmmm ... So are the Tune and Load knobs on my linear! :-D Regards, JS |
Coils, why?
Cecil Moore wrote:
John Smith wrote: A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Looks like linear loading to me. All joking aside, the point is, a helical/circular coil is not a magical arrangement ... but then, you already knew that. I have constructed shortened antennas using pvc pipe with sets of parallel holes drilled on each side and the conductor "laced" through the pipe and forming "loops" on each side of the antenna--if nothing else, the visual of them provoked responses ... I now use such an arrangement on the bottom helical of my Vincent 20m (modified gamma.) Regards, JS |
Coils, why?
Owen wrote:
"Not to imply that Efficiency = Q." It does. Q = energy stored per cycle / energy lost per cycle. Q = XsubL / R Efficiency = output / input. Output is the energy given back by the coil when its field collapses. Input is the energy required to charge the inductor`s field plus the energy required to supply the losses. Net output is equivalent to coil reactance and net input is equivalent to the effective series resistance loss. Therefo Q = Efficiency. Best regards, Richard Harrison, KB5WZI |
Coils, why?
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Coils, why?
"John Smith" wrote in message ... John Smith wrote: Poor old W8JI has taken quite a beating, it is best to realize if mistakes are made, so should it be, we are only human. He is not poor and not that old. He does not take the "beating" for no reason, but in response to some of his extreme statements or fallacies that he proclaims as a gospel on his web site and on the reflectors. If he was more human, he would realize some of the mistakes in his thinking/knowledge/proselytizing, correct them and GIVE a credit where it's due. However, this individual has prepared some nice pages, he has a nice way of writing which are easy to logically follow. Newbies, if they stumble upon his pages, must surely benefit tremendously. That is nice and to many useful (better source is ARRL Handbook), but included in that are some errors and misinformation trumpeted as a gospel according to W8JI which does not serve the ham community well. He is doing his web "service" not from purely ham philanthropic reasons, but making business and monetary gains via "W8JI Engineering" and lately "DX Engineering" products and promotion. (Using "Engineering" label without having engineering degree, college degree or being member for engineers association, required by most states.) Now, as I have stated, I have no real horse in the particular argument which dominates this group--I simply wish to recognize his good work and give him proper credit. If unknowingly slight men of good intentions we may lose them--NOT a good thing ... I have a horse in some of the arguments, because when I saw some fallacies being propagated or when I was attacked by him for some of my statements about my findings and him trying to play in public forum as "all-knowing guru" to this "know-nothing" real engineer (with some awarded design experience and bunch of world records), I simply don't take the crap and react. Just a brief unpsychological profile of W8JI: he never admits to be wrong, he jumps on "dummies" from his high horse, if he finds he might have been wrong, he will never admit it, but obfuscates the issue, fogs it with smoke and mirrors, goes quiet for a while and later emerges as a guru appropriating the critic's idea and proclaiming it as new gospel on his pages. He likes to criticize the other sources as misleading, while himself has a plenty of it on his pages. Been there about 5 times and I would be critical about his "gospel". (And you don't not know about some of the stuff and backstabbing that goes on off the web pages.) http://www.w8ji.com/loading_inductors.htm Prime example of another "wrongo". The main problem with loading stubs in antenna situations is that they have RF current flowing on the loading wires, which interact (cancellation) with the element they are "serving" especially when folded back or forward on the element (3 wires interacting). The best way, if must to use loading stubs, is to have them to go 90 degrees off the element. The coil does not have that effect, there is just drop of current across the coil, while rest of the current along the element is not disturbed. This effect is magnified when using in arrays, which was verified in real life by W6?? when they replaced loading stubs with coils and saw dramatic improvement in the 3 el. KLM 80 m beam - better gain and remarkable improvement in the pattern, F/B. Warm regards to all, That too, from snowy NE! JS 73 Yuri, K3BU.us |
Coils, why?
Hal Rosser wrote:
I tried Linear Loading with a 10-meter Mobile antenna - just to try it out. If I recall, the performance was about the same as a coil-loaded antenna. The reason I like coils is that they fit nicely inside (or outside) a piece of PVC pipe, and makes antenna-making easier. 3D coils are superior to 2D linear loading schemes. So far, no linear loading scheme can equal the performance of a high-Q coil with its extra dimensional advantage. -- 73, Cecil http://www.w5dxp.com |
Coils, why?
Richard Harrison wrote:
... Best regards, Richard Harrison, KB5WZI Richard: I'll break down and be honest, I cannot "dust you off." However, how much "Q" is there in a straight wire radiator? And, in "linear loading" that much of an "hinderence?" You know, I have no horse here either--come to think of it! Warm regards, JS |
Coils, why?
Owen wrote:
"So, you are saying that if a coil has a Q of 500, its efficiency is 500, and that there is more output (power) than input (power)?" Don`t I wish! Our energy problems would be solved. Owen caught me not thinking everything through and making a bone-headed mistake. I`ll take some time to rethink the relation between Q and efficiency. Best regards, Richard Harrison, KB5WZI |
Coils, why?
Yuri Blanarovich wrote:
... 73 Yuri, K3BU.us Yuri, I don't know if we are dealing with cultural differences or not, but damn dude, you are TOO BIG OF A WASTE OF MY TIME ... PLONK BIG TIME! Now .... Warm regards, JS P.S. But still, plonk! |
Coils, why?
John Smith wrote:
Why not: ___ ___ | | | | | | | | | | | | | | | | | | | | | | | | | | | | ___| |___| etc. A "flattened" coil, first time I see one used is Vincents' DLM, anyone? Regards, JS P.S. Excuse the bad ascii graphics ... Hmm... Obviously, I have missed something in my "education." In a front end tuner, sometimes, hi-Q is MOST desirable ... In my antennas, a Q of 20 to 50 is ok, heck 100 is ok ... I don't see the point above that ... Regards, JS |
Coils, why?
John Smith wrote:
... Hmm... Obviously, I have missed something in my "education." In a front end tuner, sometimes, hi-Q is MOST desirable ... In my antennas, a Q of 20 to 50 is ok, heck 100 is ok ... I don't see the point above that ... Regards, JS Well, too fast there, in traps, a hi-Q is desired by me, but heck, 200 is OK! JS |
Coils, why?
Yuri Blanarovich wrote:
... 73 Yuri, K3BU.us Oh yeah, I trust you are here legally, right? Would hate to call immigration on "another one!" chuckle JS |
Coils, why?
John Smith wrote:
"However, how much "Q" is there in a straight wire radiator?" That`s easy. Arnold B. Bailey has already done all the work for us in "Antennas and Other Receiving Antennas", but it depends on how fat the wire is. For a thin-wire dipole, the 3 dB down bandwidth is 34%, so F2-F1/Fo=0.34. For Bailey`s 200 MHz antenna, BW = F/Q and Q = 200/68= 2.94. Best Regards, Richard Harrison, KB5WZI |
Coils, why?
Richard Harrison wrote:
... For a thin-wire dipole, the 3 dB down bandwidth is 34%, so F2-F1/Fo=0.34. For Bailey`s 200 MHz antenna, BW = F/Q and Q = 200/68= 2.94. Best Regards, Richard Harrison, KB5WZI Thanks Richard, good math! So many won't take the time ... Warm regards, JS |
Coils, why?
"John Smith" wrote in message ... Yuri Blanarovich wrote: ... 73 Yuri, K3BU.us Oh yeah, I trust you are here legally, right? Would hate to call immigration on "another one!" chuckle JS Your "brilliance" is blinding! I admire Cecil for having patience to engage with such brilliant minds. :-) Time to grow up from diapers? Yuri |
Coils, why?
Yuri Blanarovich wrote:
... Your "brilliance" is blinding! I admire Cecil for having patience to engage with such brilliant minds. :-) Time to grow up from diapers? Yuri Ahhh, that just felt good ... JS |
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