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#1
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Howdy NGers,
I was curious about another "miracle" short vertical, being subject of great interest, patent by Robert Vincent and Physics dept. of University of Rhode Island. I got up at 4 am, drove to Boxboro ARRL convention and eager to see what are we missing. Not much! Giveaway was opening statement something like: how to make shortened antenna with more gain (compare to what? I guess light bulb :-) In the "theoretical" portion of the presentation audience was told that current across the helical coil decreases away from the feed point, while across loading coil it stays constant. Due overcrowding of "inventor" I did not persist in breaking through and asking for enlightenment. Author claims more gain (familiar), better bandwidth (doesn't get it why) and small size (of course). Showing measured graphs with current and phase distribution along the radiator. Works very well! (Many stations worked.) He showed how to measure current at the antenna using ferrite pickup transformer way up the antenna and cables to the instrument (handsomely detuning and distorting the measurements). I suspect that "broad bandwidth", (SWR 2:1) was achieved thanks to losses in the coils and dielectric, as "confirmed" by his statement that coils were fried when power was applied. What is it? Basically helically wound coil starting from the base, about half way up the radiator, then piece of straight tubing, than loading coil, then tubing and in some case top hat (works better :-). Matching to 50 ohms is done by picking tap at the base, few coil turns up. That is 3D version. He showed some "2D" versions, having "coils" made of basically coil formed as hairpin loops instead of classic solenoid, also the loading coil. So kind of 2D - 3D antenna :-) I wanted to make a bet that my single loading coil loaded vertical would cream the "miracle", but there were so many worshippers paying compliments to the inventor, that I resigned not to stay for the second hour of lecture how to build it. I saw no trace of any modeling, just experiments using wrong tools. So brace yourselves for another "miracle" in the arsenal of very small and more efficient antennas. It should be a hit with CBers and other suckered users. So that's it (oh, no chokes in the feedlines), I hope U of RI is proud of this breakthrough, I can sleep well now. Back to DR1. Yuri, K3BU with more info that could have saved lotsa experimenting at http://www.k3bu.us/loadingcoils.htm |
#3
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m
Does it also plug into the house wiring for improved TV reception? Gotta love junk-science! Howard Not sure, but it is apparently very easy to scale up or down by simply reducing/enlarging it on the copier by factor x. No kidding! Apparently works well into the UHF bands :-) Who needs EZnec. Can you picture all them wizards joining forces for FracEHDLMCFA gizmo? Yuri |
#4
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Yuri Blanarovich wrote:
In the "theoretical" portion of the presentation audience was told that current across the helical coil decreases away from the feed point, while across loading coil it stays constant. I've often wondered at exactly what crossover point a helical coil turns into a loading coil. If one adds a one inch stinger to a helical coil, does that turn it into a loading coil? How about a one foot stinger? Is a one foot long loading coil not a helical coil? Does a one foot long loading coil really have less phase shift than a one foot long piece of wire? On a center-loaded mobile antenna, how can the ARCCOS of the current at the feedpoint be zero degrees and the ARCCOS of the current at the tip be 90 degrees without there being 90 degrees between the feedpoint and the tip? (When are you going to invite everyone over to Bar-B-Q that sacred cow?) -- 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! =----- |
#5
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![]() I've often wondered at exactly what crossover point a helical coil turns into a loading coil. If one adds a one inch stinger to a helical coil, does that turn it into a loading coil? How about a one foot stinger? Is a one foot long loading coil not a helical coil? Does a one foot long loading coil really have less phase shift than a one foot long piece of wire? On a center-loaded mobile antenna, how can the ARCCOS of the current at the feedpoint be zero degrees and the ARCCOS of the current at the tip be 90 degrees without there being 90 degrees between the feedpoint and the tip? (When are you going to invite everyone over to Bar-B-Q that sacred cow?) -- 73, Cecil http://www.qsl.net/w5dxp We have to wait for the patent 'splaining the "miracle". One thing I "discovered" that winding the wire either as a coil or simply taping it to the wood or plastic dielectric detunes the heck of it (losses, making it look more "broadband"). I taped the wire of quarter wave vertical to the bamboo pole, and it was way off resonance. When I put plexiglass spacers, insulators, bingo, right on frequency. Coil is a coil and in the antenna circuit it behaves that way. One thing is comapring quarter wave electrical length (loaded) radiator to quarter wave monopole, another thing is making it electrically longer, loading it and then comparing to quarter wave radiator. From presentation it was hard to judge what exactly was DLM electrically equivalet to. We might have clinic on verticals over "perfect" salty water soon, we are closing on waterfront property near the Ocean Gate old AT&T huge Rhombic antenna farm and looking for some juicy coiled sausage to BBQ. I think that hanging cow bell and flourescent light on the DLM would make it one class better, maybe 120% efficient antenna :-) What will they think of next? 73 Yuri, K3BU.us |
#6
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Yuri, your criticism is perfectly sound.
To sum up, the key to antenna radiating efficiency is SIMPLICITY. The more simple the construction of an antenna the more efficient it will be. It is intuitivly obvious. Every complication is sure to introduce loss. --- Reg |
#7
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Reg Edwards wrote:
The more simple the construction of an antenna the more efficient it will be. An isotropic is pretty simple but I don't know how to feed it. :-) -----= 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! =----- |
#8
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![]() "Cecil Moore" wrote in message ... Reg Edwards wrote: The more simple the construction of an antenna the more efficient it will be. An isotropic is pretty simple but I don't know how to feed it. :-) From the inside. Ed wb6wsn |
#9
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I wish someone WOULD come up with a 10-ft vertical for 80 meters with the
same gain and bandwidth as a simple dipole "Yuri Blanarovich" wrote in message ... Howdy NGers, I was curious about another "miracle" short vertical, being subject of great interest, patent by Robert Vincent and Physics dept. of University of Rhode Island. I got up at 4 am, drove to Boxboro ARRL convention and eager to see what are we missing. Not much! Giveaway was opening statement something like: how to make shortened antenna with more gain (compare to what? I guess light bulb :-) In the "theoretical" portion of the presentation audience was told that current across the helical coil decreases away from the feed point, while across loading coil it stays constant. Due overcrowding of "inventor" I did not persist in breaking through and asking for enlightenment. Author claims more gain (familiar), better bandwidth (doesn't get it why) and small size (of course). Showing measured graphs with current and phase distribution along the radiator. Works very well! (Many stations worked.) He showed how to measure current at the antenna using ferrite pickup transformer way up the antenna and cables to the instrument (handsomely detuning and distorting the measurements). I suspect that "broad bandwidth", (SWR 2:1) was achieved thanks to losses in the coils and dielectric, as "confirmed" by his statement that coils were fried when power was applied. What is it? Basically helically wound coil starting from the base, about half way up the radiator, then piece of straight tubing, than loading coil, then tubing and in some case top hat (works better :-). Matching to 50 ohms is done by picking tap at the base, few coil turns up. That is 3D version. He showed some "2D" versions, having "coils" made of basically coil formed as hairpin loops instead of classic solenoid, also the loading coil. So kind of 2D - 3D antenna :-) I wanted to make a bet that my single loading coil loaded vertical would cream the "miracle", but there were so many worshippers paying compliments to the inventor, that I resigned not to stay for the second hour of lecture how to build it. I saw no trace of any modeling, just experiments using wrong tools. So brace yourselves for another "miracle" in the arsenal of very small and more efficient antennas. It should be a hit with CBers and other suckered users. So that's it (oh, no chokes in the feedlines), I hope U of RI is proud of this breakthrough, I can sleep well now. Back to DR1. Yuri, K3BU with more info that could have saved lotsa experimenting at http://www.k3bu.us/loadingcoils.htm --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.732 / Virus Database: 486 - Release Date: 7/30/2004 |
#10
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Hal Rosser wrote:
I wish someone WOULD come up with a 10-ft vertical for 80 meters with the same gain and bandwidth as a simple dipole Heck Hal, a 66 ft. vertical for 80m doesn't even have the same gain as a dipole. -----= 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! =----- |
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