Re: Topband: Fw: GAP VERTICAL QUESTION
On 12/15/2012 7:59 AM, DAVID CUTHBERT wrote: Mike that QTH looks alot like the Great Salt Lake of Utah where I have operated a few 160 meter 'tests running a balloon vertical. Dave WX7G I learned about this QTH from Earl K6SE (SK). The terrain to the north isn't so great (high mountains), but toward CONUS is literally miles of salty lake bed. Also, it was pretty wet the year I was there (2006) which I am sure didn't hurt matters. I am glad I wasn't using a balloon antenna, however, because the winds got so bad Saturday night of the contest it broke one of the ridge poles on my little operating tent. The wind then had that broken side of the tent pinning me against the operating table :-) 73, Mike W4EF... ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Mike that QTH looks alot like the Great Salt Lake of Utah where I have operated a few 160 meter 'tests running a balloon vertical. Dave WX7G On Fri, Dec 14, 2012 at 9:52 AM, Michael Tope w...@dellroy.com wrote: On 12/13/2012 3:14 PM, Tom W8JI wrote: Somehow they thought moving the feedpoint eliminated the need for radials with an electrically short antenna, when the real mechanism was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 wave above ground and it only got a tiny bit weaker. The groundplane still had 8 radials, but they were hundreds of feet in the air. There was some more stuff about offsetting the feedpoint in that handout, but nothing that remotely applied to a fractional wavelength vertical just sitting on the dirt with a few radials laying directly on the lawn. They got rid of lossy traps and loading coils by using even lossier coax and some folded wires for a loading system. This is all why, as frequency increases and the current and voltage moves up the antenna, the GAP on most bands isn't terribly bad. This also why it is a real dog of an antenna on 160 and 80, where it is very short electrically, has no ground system, has an exceptionally poor loading method, and where it folds the radiator back and forth which suppresses radiation resistance. This is why a ten foot mobile antenna can tie it or beat it on 160, and why it is reasonably on par with anything else on most bands above 80 meters. 73 Tom I got hold of a brand new voyager about 7 years ago. The first thing I did was throw away all that yellow coax stuffed inside the bottom half. The fiberglass GAP for the elevated feed point makes a nice insulator for a center loading coil. Then I added some top hat wires with dimensions per WX7G's recommendation and fed the antenna from the bottom as a standard ground mounted vertical with a bunch of radials. For 80 meters, I put a short yard arm at the top with a pulley and hung a wire in parallel with the aluminum radiator. For only being 45ft tall this antenna has worked surprisingly well. I've since lengthened it to 56ft and added an additional parallel wire for 40 meters. I use an Ameritron RCS-4 remote switch at the base to select between 160 or 80/40 (the 80 and 40 meter vertical wires are tied together). I use a 50 to 12.5 ohms Unun on the 160 side to raise the feedpoint Z up to 50 ohms. With all these modifications done in haste before various contests it aint pretty to look at, but it does seem to hold its own against folks with shunt-fed towers and inverted-Ls (at least the ones who don't use overly active antenna tuners :-) ). Here are some pictures of it when I took a trip to one of the dry lake beds north of here: http://www.dellroy.com/W4EF's-**Ham-Radio-Page/CQ160/2006.htmhttp://www.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm 73, Mike W4EF... __**_ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Wow, Dave! That sounds great!! Could you support a vertical 1/2 wave for 160 with a balloon? You could end -feed it at the base through a 1/4 wave of 450 ohm ladder line and it would be a FEARSOME 160 antenna! And the whole radial issue goes away!! I've operated a vertical 1/2 wave for 40m this way with GREAT success! Even added a reflector and director to make a full-size vertical 3-element yagi for 3Y0 and SE Asia on the evening 150 degree LP - Great DX antenna! Worked Bouvet first call in a HUGE east coast evening pile-up! :-) Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of DAVID CUTHBERT Sent: Saturday, December 15, 2012 10:59 AM To: Michael Tope Cc: topband@contesting.com Subject: Re: Topband: Fw: GAP VERTICAL QUESTION Mike that QTH looks alot like the Great Salt Lake of Utah where I have operated a few 160 meter 'tests running a balloon vertical. Dave WX7G On Fri, Dec 14, 2012 at 9:52 AM, Michael Tope w...@dellroy.com wrote: On 12/13/2012 3:14 PM, Tom W8JI wrote: Somehow they thought moving the feedpoint eliminated the need for radials with an electrically short antenna, when the real mechanism was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 wave above ground and it only got a tiny bit weaker. The groundplane still had 8 radials, but they were hundreds of feet in the air. There was some more stuff about offsetting the feedpoint in that handout, but nothing that remotely applied to a fractional wavelength vertical just sitting on the dirt with a few radials laying directly on the lawn. They got rid of lossy traps and loading coils by using even lossier coax and some folded wires for a loading system. This is all why, as frequency increases and the current and voltage moves up the antenna, the GAP on most bands isn't terribly bad. This also why it is a real dog of an antenna on 160 and 80, where it is very short electrically, has no ground system, has an exceptionally poor loading method, and where it folds the radiator back and forth which suppresses radiation resistance. This is why a ten foot mobile antenna can tie it or beat it on 160, and why it is reasonably on par with anything else on most bands above 80 meters. 73 Tom I got hold of a brand new voyager about 7 years ago. The first thing I did was throw away all that yellow coax stuffed inside the bottom half. The fiberglass GAP for the elevated feed point makes a nice insulator for a center loading coil. Then I added some top hat wires with dimensions per WX7G's recommendation and fed the antenna from the bottom as a standard ground mounted vertical with a bunch of radials. For 80 meters, I put a short yard arm at the top with a pulley and hung a wire in parallel with the aluminum radiator. For only being 45ft tall this antenna has worked surprisingly well. I've since lengthened it to 56ft and added an additional parallel wire for 40 meters. I use an Ameritron RCS-4 remote switch at the base to select between 160 or 80/40 (the 80 and 40 meter vertical wires are tied together). I use a 50 to 12.5 ohms Unun on the 160 side to raise the feedpoint Z up to 50 ohms. With all these modifications done in haste before various contests it aint pretty to look at, but it does seem to hold its own against folks with shunt-fed towers and inverted-Ls (at least the ones who don't use overly active antenna tuners :-) ). Here are some pictures of it when I took a trip to one of the dry lake beds north of here: http://www.dellroy.com/W4EF's-**Ham-Radio-Page/CQ160/2006.htmhttp://w ww.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm 73, Mike W4EF... __**_ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
On 12/13/2012 3:14 PM, Tom W8JI wrote: Somehow they thought moving the feedpoint eliminated the need for radials with an electrically short antenna, when the real mechanism was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 wave above ground and it only got a tiny bit weaker. The groundplane still had 8 radials, but they were hundreds of feet in the air. There was some more stuff about offsetting the feedpoint in that handout, but nothing that remotely applied to a fractional wavelength vertical just sitting on the dirt with a few radials laying directly on the lawn. They got rid of lossy traps and loading coils by using even lossier coax and some folded wires for a loading system. This is all why, as frequency increases and the current and voltage moves up the antenna, the GAP on most bands isn't terribly bad. This also why it is a real dog of an antenna on 160 and 80, where it is very short electrically, has no ground system, has an exceptionally poor loading method, and where it folds the radiator back and forth which suppresses radiation resistance. This is why a ten foot mobile antenna can tie it or beat it on 160, and why it is reasonably on par with anything else on most bands above 80 meters. 73 Tom I got hold of a brand new voyager about 7 years ago. The first thing I did was throw away all that yellow coax stuffed inside the bottom half. The fiberglass GAP for the elevated feed point makes a nice insulator for a center loading coil. Then I added some top hat wires with dimensions per WX7G's recommendation and fed the antenna from the bottom as a standard ground mounted vertical with a bunch of radials. For 80 meters, I put a short yard arm at the top with a pulley and hung a wire in parallel with the aluminum radiator. For only being 45ft tall this antenna has worked surprisingly well. I've since lengthened it to 56ft and added an additional parallel wire for 40 meters. I use an Ameritron RCS-4 remote switch at the base to select between 160 or 80/40 (the 80 and 40 meter vertical wires are tied together). I use a 50 to 12.5 ohms Unun on the 160 side to raise the feedpoint Z up to 50 ohms. With all these modifications done in haste before various contests it aint pretty to look at, but it does seem to hold its own against folks with shunt-fed towers and inverted-Ls (at least the ones who don't use overly active antenna tuners :-) ). Here are some pictures of it when I took a trip to one of the dry lake beds north of here: http://www.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm 73, Mike W4EF... ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
This is ~true only for a far field analysis (as defined by NEC software) for a vertical monopole -- which includes the propagation losses present in the radiated fields from that monopole, over an infinite, FLAT, real-earth ground plane. However that is not reality. I think what is going here is we have a bunch of anecdotal results based on one unknown compromised system compared to another compromised system when dozens of things are changed, and we are trying to generate physics to support one thing as being the cause. I am 100% sure, based on dozens of comparisons with three stations located not too far from me, that it is pretty difficult to make an antenna of reasonable size and construction -20dB based on ground system shortfalls. Some of this has gone beyond reasonable or logical, and is poisoning our knowledge base. In Toledo, a good friend lived on a small city lot behind a restaurant. His backyard, the only place for an antenna, was just a few feet deep and maybe 100 feet long. He tied in everything he could; heating ducts, plumbing, short radials, a short chain link fence. He was consistently, over many years, within a few dB of my full size quarter wave in an ideal soil and ground system. This was night after night, DX or local, over and over again. Another fellow in a neighborhood had a short TV tower with inverted L, and his radials ran to a sidewalk maybe ten or fifteen feet away. He had radials crossing the ceiling of his basement. His signal was the same way. Another station, W8KWN, just had driven rods. NONE of these stations were even close to 20 dB down. It was more like 5 dB to maybe a just little more at times, and a little less at times. The driven rods were the worse system, but even they were not -20 dB. Now there was one station who had bad luck. He had bigger back yard, and it was just full of wires and antennas. He had all these bamboo supports and quads and other things, a yard full of stuff. His signal was so weak he actually would swear and cuss at the other guys and accuse them of illegal power because his antennas were so good in his own mind that there was not way these other guys would beat him so badly unless they were cheating. No amount of conversation could convince him he had the problem. In my experience, it is more about having a neat, clean, uncluttered installation and not doing things grossly wrong, like using coaxial stubs for loading inductance or packing 900 pounds of antennas into a two pound back yard area, than any sort of grounding issue. The only -10 dB or -20 dB things I ever see are people who jam too much in small area, or have some other serious system error they created but just cannot see. My ten foot tall mobile antenna with a pickup truck for a ground is about 20 dB down from my TX antenna. If someone else has that issue with a 50 foot tall inverted L, they better look at something other than a compromised ground system. They have a more serious issue. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
I have already spoken extensively that your assertion is not proved, NOR is the counter-assertion proved. I have no intentions of adding to that. I am not persuaded either way, though BOTH sides of that question have attractive points. I am waiting for something new to emerge, like helicopter measurements out 50 km from operational ceiling down to the ground. Since the near field NEC4 predicts the notchless 3 or 4 km helicopter measured data, we have to get it out where the NEC process predicts the notch and measure it there. That will settle it. If it maintains down to the ground, then we can beat the LLNL people to death with it and they will have to fix NEC. Otherwise, we don't know. To the point in question, you are asserting that if the notch under the typical far field elevation plot was filled in, THAT would account for the 4 dB? I give you that the loss would lessen if the gain at the ground was equal to say 15 degrees and smooth going up, but the integration of the spherical far field data asserts that OVER HALF THE POWER is going to loss. The only way you get that back is to put it over sea water. Anyone experiencing the marvelous increase in vertical performance at the edge of/over sea water will tell you emphatically that you DO get it over sea water and you decidedly DO NOT get that over inland dirt. Frankly the difference seems a lot more than the difference in the plots. Filling up 20 degrees out of 360 will won't get you back to only 3 dB down. The original question still stands. It is not related to your assumption, or not. Anyone wants to tackle the idea that the far field plot of NEC4 is off by 4 dB, in order to keep from acknowledging heavy foreground induced ground loss, have at it. It should be interesting. 73, Guy. On Thu, Dec 13, 2012 at 7:06 AM, Richard Fry r...@adams.net wrote: Guy Olinger wrote: You can model a near perfect commercial grade radial field, with a radial system apparent series resistance of a few tenths of an ohm, and NEC4 will still come back with an overall loss of 3 to 4 dB. This is ~true only for a far field analysis (as defined by NEC software) for a vertical monopole -- which includes the propagation losses present in the radiated fields from that monopole, over an infinite, FLAT, real-earth ground plane. ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
So here's a question. I have a vertical mounted on a cliff side that performs incredibly. My amateur's approach to figuring out why is that I modeled it in EZNEC as being elevated 400 feet. That shows it performing nearly as well as if it were on a tiny island in the great ocean. Is it correct that an elevated feed point greatly reduces the ground losses? On Dec 13, 2012, at 12:35 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: I have already spoken extensively that your assertion is not proved, NOR is the counter-assertion proved. I have no intentions of adding to that. I am not persuaded either way, though BOTH sides of that question have attractive points. I am waiting for something new to emerge, like helicopter measurements out 50 km from operational ceiling down to the ground. Since the near field NEC4 predicts the notchless 3 or 4 km helicopter measured data, we have to get it out where the NEC process predicts the notch and measure it there. That will settle it. If it maintains down to the ground, then we can beat the LLNL people to death with it and they will have to fix NEC. Otherwise, we don't know. To the point in question, you are asserting that if the notch under the typical far field elevation plot was filled in, THAT would account for the 4 dB? I give you that the loss would lessen if the gain at the ground was equal to say 15 degrees and smooth going up, but the integration of the spherical far field data asserts that OVER HALF THE POWER is going to loss. The only way you get that back is to put it over sea water. Anyone experiencing the marvelous increase in vertical performance at the edge of/over sea water will tell you emphatically that you DO get it over sea water and you decidedly DO NOT get that over inland dirt. Frankly the difference seems a lot more than the difference in the plots. Filling up 20 degrees out of 360 will won't get you back to only 3 dB down. The original question still stands. It is not related to your assumption, or not. Anyone wants to tackle the idea that the far field plot of NEC4 is off by 4 dB, in order to keep from acknowledging heavy foreground induced ground loss, have at it. It should be interesting. 73, Guy. On Thu, Dec 13, 2012 at 7:06 AM, Richard Fry r...@adams.net wrote: Guy Olinger wrote: You can model a near perfect commercial grade radial field, with a radial system apparent series resistance of a few tenths of an ohm, and NEC4 will still come back with an overall loss of 3 to 4 dB. This is ~true only for a far field analysis (as defined by NEC software) for a vertical monopole -- which includes the propagation losses present in the radiated fields from that monopole, over an infinite, FLAT, real-earth ground plane. ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
So here's a question. I have a vertical mounted on a cliff side that performs incredibly. My amateur's approach to figuring out why is that I modeled it in EZNEC as being elevated 400 feet. That shows it performing nearly as well as if it were on a tiny island in the great ocean. Is it correct that an elevated feed point greatly reduces the ground losses? That makes sense because the VOLTAGE and CURRENT of the antenna, each of which cause loss problems, are remote from earth in the model. If BOTH the electric and magnetic fields do not have significant intensity in lossy earth, there isn't as much loss. However, the idea behind the GAP antenna falls quickly apart because they did not move the antenna away from earth. They simply moved the feedpoint around. We can move the feedpoint around in a short vertical until we are bleeding from the fingers, and loss remains the same. The only way loss changes is if we move the voltage and current up away from earth. I'm not sure what GAP's policy is now, but when questioned years ago about how the magic elevated feedpoint with the yellow lightning bolt worked, they handed out a paper about a very tall broadcast tower. They said the paper shows how an elevated feedpoint reduces loss. The paper actually said nothing of the sort. The paper said a halfwave tall AM broadcast tower, operating on the low end of the AM broadcast band, had just very slightly less field strength when it was converted from an end fed half wave with 120 radials to a groundplane with eight radials 1/4 wave above ground. Somehow they thought moving the feedpoint eliminated the need for radials with an electrically short antenna, when the real mechanism was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 wave above ground and it only got a tiny bit weaker. The groundplane still had 8 radials, but they were hundreds of feet in the air. There was some more stuff about offsetting the feedpoint in that handout, but nothing that remotely applied to a fractional wavelength vertical just sitting on the dirt with a few radials laying directly on the lawn. They got rid of lossy traps and loading coils by using even lossier coax and some folded wires for a loading system. This is all why, as frequency increases and the current and voltage moves up the antenna, the GAP on most bands isn't terribly bad. This also why it is a real dog of an antenna on 160 and 80, where it is very short electrically, has no ground system, has an exceptionally poor loading method, and where it folds the radiator back and forth which suppresses radiation resistance. This is why a ten foot mobile antenna can tie it or beat it on 160, and why it is reasonably on par with anything else on most bands above 80 meters. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Short version: *** WARNING: Most locations do not have the fortunate circumstances to support sparse or miscellaneous radial systems without exaggerated loss, and the builder with constrained circumstances should attempt counterpoise solutions designed specifically for those circumstances. Long version: I think the main point is being missed here. First of all RBN is showing changes well in excess of 6 dB with the removal of loss by replacing a faint radial system with an FCP. Remember that an FCP HAS NO GAIN. It only reduces loss. If the signal went up ten dB, it's because 10 dB of loss was removed from the system. Doesn't matter if we don't know how to calculate it with our stuff. IF it was a complex change, involving changing the wire overhead (other than adding the FCP and moving the feed to 8 feet in the air), or moving the location of the antenna, then the answer clearly cannot be cleanly attributed to any one issue. Some reported changes added together MULTIPLE loss remediations plus improvements to the radiator and produced what can only be termed stark improvements in overall performance. A few of these are easily in excess of 20 dB because of everything that was done at the same time. I certainly do not count those as pure ground loss improvements. But neither is there any reason to throw away reported results, calling them anecdotal with a condescending tone of voice as if that were some kind of disease. Anytime one can clean up that much cr*p at one time, one deserves congratulations, not being hounded on the reflector, as has happened to some. Nor should starting out with a cr*ppy situation disqualify the report, or make its numbers poison. *I* would fairly agree with a 6 dB limit to the possible change, in situations that were absent a long list of troublesome loss contributors linked to ground coupling. I would agree, given such pristine conditions as I would expect to measure on your cleared out, flat, expansive, lovely rural acres of electrically unpolluted farm land. Nor would I disagree that there are some with severely restricted radials on small lots that get away with it to some degree, simply due to serendipitous or deliberately cleaned-up backyard circumstances. WX7G I believe has done that and is getting away with it using NINETY 12 to 24' radials. But we should note there are many situations where there is not enough space or the circumstances to attempt WX7G's successful enough limited method. What is going wrong is that current ADVICE is telling people that ANY radials, and even merely a ground rod, will NEVER exceed six dB down from full size. And with that guidance, they are putting down faint imitations of a commercial radial field, expecting with a 1500 watt amp they will be equal to you, if they could only get you to reduce power to 375 watts. There should be SOMEBODY out there like that, as in the story you tell. There is a law of averages. But there are many, many more who have drunk the koolaid, followed the advice, and had very disappointing results. Some here maintain that disappointing can't be measured in dB, therefore doesn't count, and should be ignored, poisons the database. Disappointing is abstract or conjectural unless it has happened to oneself. Then one bristles when accused of purveying disinformation. Once someone's backyard has stuff from the list of troublesome loss contributors, the chances of being penalized ONLY six dB with a faint radial imitation are getting slim. The loss contributors include dirt quality from the poorer end of the spectrum, particularly in urban circumstances, or where the land has been leveled out for construction with dirt or even rubble useless for anything else and merely coated with enough good dirt to support grass. They include conductors in the ground, or any conductor close to antenna or radials that couples dirt, the list goes on. Getting the bottom of the vertical up 8 feet to an FCP decreases coupling to all that stuff. Faint radial systems on/in the dirt do not shield an antenna from heavily coupling earth made of whatever in the immediate region underneath the feed. Since an FCP provides no shielding of ground, as there is with a proper radial installation, there is a last dB or two of ground loss from the vertical conductor that it cannot mitigate. So if as you put forth, the depth of that trouble can ONLY be 6 dB, then the absolute mitigation of loss from an FCP would be 4 dB, at best 5. However, RBN changes are 7, 10, 12, 15 and some larger which I keep in the reserved for watching column. 7 to 10 is common. This far exceeds the 4 or 5 db, meaning that back yards are COMMONLY nastily lossier than the ideal. Since I can run models that give ridiculous loss figures approaching 20 dB over average ground that is perfectly homogenous without any of the nasties around, there is nothing to keep me from simply hearing people's stories just as they tell it, with no reason to
Topband: Fw: GAP VERTICAL QUESTION
My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do that .. private emails are ok..especially it the topic gets out of hand and we get a large volume of comments (Tree please dont shoot me before Christmas my wife will miss me.) ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do that .. private emails are ok..especially it the topic gets out of hand and we get a large volume of comments (Tree please dont shoot me before Christmas my wife will miss me.) ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.comwrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do that .. private emails are ok..especially it the topic gets out of hand and we get a large volume of comments (Tree please dont shoot me before Christmas my wife will miss me.) ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
The question is not How would you set up a contest station?… it is What is practical to keep on air in a Senior Living situation? Now if you have a bunch of grand kids you can talk into installing radials all the better. Or if you have a fence along which you could install an elevated counterpoise all the better. But my central contention is that wire is going to outperform a GAP below 40 meters. On Dec 12, 2012, at 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do that .. private emails are ok..especially it the topic gets out of hand and
Re: Topband: Fw: GAP VERTICAL QUESTION
20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do that .. private emails are ok..especially it the topic gets out of hand and we get a large volume of comments (Tree please dont shoot me before Christmas my wife will miss me.)
Re: Topband: Fw: GAP VERTICAL QUESTION
Correction, 100X the loss. The deal difference between a single ground rod and a BC station ground will be about 6 dB. Dave WX7G On Dec 12, 2012 1:13 PM, DAVID CUTHBERT telegraph...@gmail.com wrote: 20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX for the rest of the bands. So my question is does anyone have actual experience with these antennas (especially the voyager) as compared to other antennas for a specific frequency.? Now guys .. I know you cant really compare a 6 element beam to a vertical of this kind but I am talking about a comparison that is realistic.. like how does it hear, tune, match get out compared to something like another vertical or a dipole up some reasonable distance. I sure hope this has not opend another can of worms.. some how I seem to do
Re: Topband: Fw: GAP VERTICAL QUESTION
FWIW, at one point on a 5 acre remote parcel I had a GAP Voyager, GAP Titan, 80/160 parallel Inv-L over 120/125' radials, a 160M Inv-V, a F-12 C-4SXL beam at 54', and homemade vertical fan dipoles for 10-40M. Tall 70-85' trees that later burned in a forest fire held up the wires. The GAPS were just that...always at the bottom of the RF food chain. The vertical dipoles were down in strength from the F-12 beam some, yet I heard and worked everything the beam did when compared. They are a good alternative to a vert on the same band if supports are available. I had verts for 40 and 20 over a dense radial field (~60), but removed them when the vertical dipoles prevailed. The Inv-L worked all bands 10-160, with varying results depending on the other antennas and signal direction/time of day. I fed it with both coax plus RF chokes at both ends of the run, and twin-lead over the few years it was up. It was a full size vert on 80 due to a second wire parallel to the 160 L fed at the same point. The twin-lead fed Inv-V did the same for all bands, and had good gain on 10-40 off the ends. The Inv-L usually beat the Inv-V at the same height (~80') on 80-160. In my experience an Inv-L for 160 would be a good choice if one could only have one wire. Tuning is critical for multi-band ops. During this experiment I also had a 2-el horizontal loop for 80 at 55', which was excellent for NVIS and out to ~2500 miles from KL7, and a 1000' horizontal loop at 50-80', which was not worth the effort to build. Today, only the 80 loop and F-12 beam remain at that location. 73, Gary NL7Y ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. 1% efficiency, and 99% of power dissipated in the earth with a small ground system on an inverted L antenna? I don't think that is very likely without a feedpoint in the hundreds or thousands of ohms. Even a single ground rod is likely around 50-100 ohms, and would produce signals much stronger than that. There are ways to create modest feed impedances with extreme loss. Researchers at GAP, through great effort, have found a way to combine terrible efficiency with a reasonable feedpoint impedance. Based on measurements, the GAP is somewhere around 1% efficiency on 160 and around 3% efficiency on 80 meters. Most of this loss is because the loading system (at least in large part) uses a coaxial stub, which has a Q low in the double digits, and has higher voltage applied at a poor ground system. I'm also sure much of the loss is caused by folding of current back and forth, cancelling radiation and driving radiation resistance through the floor. The bulk of the feed impedance on low bands is dissipative. It is a very high angle radiator on ten meters, but is OK on most other bands. This is quite an achievement, giving low SWR and mobile-antenna performance without actually using an antenna 8 feet long, and without a physical resistor. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) It is a half wave on 80. with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. Four short radials on an L are really not that bad compared to an antenna engineered to have very low radiation resistance and very high internal loss. I know or knew people who were quite successful with small grounds on inverted L's. An old friend (now SK) in Toledo had an inverted L on a small city lot, probably no more than ten feet deep from the house to the fence, and he was consistently within a few dB of my full size 160 vertical in a swampy area. His only long radial ran parallel to the L and underneath the L. His radials were buried to hide them, and his L was right against his ranch style house. Other people had similar antennas. One fellow had nothing but ground rods, he had no radials at all, except the wires that connected the rods. His signal was certainly less than my 1/4 wave tower with a large radial system in wet black sandy loam, but it was probably not more than 5-10 dB less. Another station was always within an S unit on any report anywhere, even Australia, and he was on a corner city lot with less than 20 feet to the sidewalks for radials and a 30-35 ft high inverted L. My conclusion is it takes great effort, or significant incredible failure, to manage to be 10-20 dB down. I really get quite a chuckle out of anecdotal day-and-night performance reports, when I think back at some of the absolutely rubbish that ran neck and neck with a quarter wave vertical in black wet swamp soil. I wonder more about how poor the one antenna was than how good the second one was. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Not all loss is visible as series resistance in the counterpoise system, which is the tack you are taking. Note that a dummy load is 50 ohms, and does not radiate worth a hoot. It takes modeling to identify some situations. One of my favorites in NEC4 results in a max gain of -18 dBi or so. This is compared to a commercial BC 1/4 wave of plus 1.2 dBi in the same ground. The reason for the extreme loss is completely counter-intuitive. We have a lot of mental simplification devices for thinking about antennas. In the end you need something to add up all the induced currents, all the losses On Wed, Dec 12, 2012 at 3:13 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: 20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I have become very skeptical about claims and the other BS put out by most companies ( maybe it is a function of age I dunno) so I wonder if these antennas really work.? The two antennas that I am interested are the Voyager DX for 160/80/40? and the Eagle DX
Re: Topband: Fw: GAP VERTICAL QUESTION
Guy, you make it sound like magic. See the IEEE paper RADIATION EFFICIENCY AND INPUT IMPEDANCE OF MONOPOLE ELEMENTS WITH RADIAL-WIRE GROUND PLANES IN PROXIMITY TO EARTH Dave WX7G On Dec 12, 2012 3:13 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: Not all loss is visible as series resistance in the counterpoise system, which is the tack you are taking. Note that a dummy load is 50 ohms, and does not radiate worth a hoot. It takes modeling to identify some situations. One of my favorites in NEC4 results in a max gain of -18 dBi or so. This is compared to a commercial BC 1/4 wave of plus 1.2 dBi in the same ground. The reason for the extreme loss is completely counter-intuitive. We have a lot of mental simplification devices for thinking about antennas. In the end you need something to add up all the induced currents, all the losses On Wed, Dec 12, 2012 at 3:13 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: 20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes, I know , some of that high band gain is horizontally polarized, but that's not all bad. Just get the vertical portion 33 feet or so and you'll be happy as Larry. The article shows that an extensive radial field may not be necessary. And a wire is a lot less visible than a big hunk of aluminum. Without trees, just top load a 43 foot (or possibly even shorter) vertical. The top loading could be a T just as easily as an L. People can argue that one all day. On Dec 12, 2012, at 11:30 AM, k6xt k...@arrl.net wrote: My first antenna, still in use, on moving to CO is a GAP Titan, advertised to load up 80 thru 10 including WARC bands. The Titan is a bit shorter than Voyager, 28 feet or something like it. The advertising is correct, it loads up 180 thru 10. But wait. Is it effective on all those bands? No. On 80 its a dummy load. On 40 it works extremely well after I added a one foot extension to the bottom wire that encircles the antenna. In some cases it is the equal of my shorty HyGain 40 at 70 ft - which probably says more about the HyGain than the GAP. For the rest its better on the traditional bands than the WARC bands. It worked a lot of DX for me for the couple years it was my only antenna. Carrying my experience to the few feet taller Voyager, and from what I've been told by Voyager users, the ant will meet its spec which is to load up on the low bands. Expectation wise I'd expect it to be like the Titan. It loads up but is otherwise a dummy load. Maybe with a batch of radials it could be made to work as well as any other extremely short vertical or GP. Not to say there's anything wrong with GAP. My brother had up an R7 which he rated about like the GAP on bands both cover. Those multiband halfwave short verticals work but you get what you pay for. 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ARRL, GMCC, CW OPS, NAQCC ARRL TA On 12/12/2012 10:00 AM, topband-requ...@contesting.com wrote: With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue this wonderful hobby.? I have heard some good things about the GAP series of antennas but the company says they do not need radials on most of them and that worries me.? Over the years I
Re: Topband: Fw: GAP VERTICAL QUESTION
Well, Tom I operate from a small city lot, although I do have some tall trees! I've done OK on 160 and 80 with a 160 inverted L and full size 80m GP - both with elevated resonant radials. (The 160 radials did meander a bit) I've worked some really good DX on 160 - VK6, 3B8, JA and 3Y0 etc. - and some deep Russians. Biggest problem for me, in the city was not being heard, it was HEARING! Once I put up a terminated loop Kaz antenna, with a preamp for receiving. All that changed - a LOT! I believe that guys are missing a good bet by not trying the elevated resonant radials under their 160 and 80m antennas -even if they have to meander a bit. In my experience,the main challenge on 160 is HEARING! Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Wednesday, December 12, 2012 4:25 PM To: Guy Olinger K2AV; Ashton Lee Cc: k...@arrl.net; topband@contesting.com Subject: Re: Topband: Fw: GAP VERTICAL QUESTION With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. 1% efficiency, and 99% of power dissipated in the earth with a small ground system on an inverted L antenna? I don't think that is very likely without a feedpoint in the hundreds or thousands of ohms. Even a single ground rod is likely around 50-100 ohms, and would produce signals much stronger than that. There are ways to create modest feed impedances with extreme loss. Researchers at GAP, through great effort, have found a way to combine terrible efficiency with a reasonable feedpoint impedance. Based on measurements, the GAP is somewhere around 1% efficiency on 160 and around 3% efficiency on 80 meters. Most of this loss is because the loading system (at least in large part) uses a coaxial stub, which has a Q low in the double digits, and has higher voltage applied at a poor ground system. I'm also sure much of the loss is caused by folding of current back and forth, cancelling radiation and driving radiation resistance through the floor. The bulk of the feed impedance on low bands is dissipative. It is a very high angle radiator on ten meters, but is OK on most other bands. This is quite an achievement, giving low SWR and mobile-antenna performance without actually using an antenna 8 feet long, and without a physical resistor. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) It is a half wave on 80. with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. Four short radials on an L are really not that bad compared to an antenna engineered to have very low radiation resistance and very high internal loss. I know or knew people who were quite successful with small grounds on inverted L's. An old friend (now SK) in Toledo had an inverted L on a small city lot, probably no more than ten feet deep from the house to the fence, and he was consistently within a few dB of my full size 160 vertical in a swampy area. His only long radial ran parallel to the L and underneath the L. His radials were buried to hide them, and his L was right against his ranch style house. Other people had similar antennas. One fellow had nothing but ground rods, he had no radials at all, except the wires that connected the rods. His signal was certainly less than my 1/4 wave tower with a large radial system in wet black sandy loam, but it was probably not more than 5-10 dB less. Another station was always within an S unit on any report anywhere, even Australia, and he was on a corner city lot with less than 20 feet to the sidewalks for radials and a 30-35 ft high inverted L. My conclusion is it takes great effort, or significant incredible failure, to manage to be 10-20 dB down. I really get quite a chuckle out of anecdotal day-and-night performance reports, when I think back at some of the absolutely rubbish that ran neck and neck with a quarter wave vertical in black wet swamp soil. I wonder more about how poor the one antenna was than how good the second one was. 73 Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Personally, I use an 80 M loop - I like it especially for stateside contest like Sweep or FD. Nice solid signal on 40M and 80M. It does much better than the Titan. But the Titan is much less maintenance and I don't have to put it up and rebuild it each year. With two hurricanes, no guying and no maintenance work at all, the antenna stays up, good SWR and I can make the occasional contact. Will I ever be the big dog - nope. I had a much better station in the mid-west, but we all make compromises,. -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Gary and Kathleen Pearse Sent: Wednesday, December 12, 2012 3:44 PM To: topband List Subject: Re: Topband: Fw: GAP VERTICAL QUESTION FWIW, at one point on a 5 acre remote parcel I had a GAP Voyager, GAP Titan, 80/160 parallel Inv-L over 120/125' radials, a 160M Inv-V, a F-12 C-4SXL beam at 54', and homemade vertical fan dipoles for 10-40M. Tall 70-85' trees that later burned in a forest fire held up the wires. The GAPS were just that...always at the bottom of the RF food chain. The vertical dipoles were down in strength from the F-12 beam some, yet I heard and worked everything the beam did when compared. They are a good alternative to a vert on the same band if supports are available. I had verts for 40 and 20 over a dense radial field (~60), but removed them when the vertical dipoles prevailed. The Inv-L worked all bands 10-160, with varying results depending on the other antennas and signal direction/time of day. I fed it with both coax plus RF chokes at both ends of the run, and twin-lead over the few years it was up. It was a full size vert on 80 due to a second wire parallel to the 160 L fed at the same point. The twin-lead fed Inv-V did the same for all bands, and had good gain on 10-40 off the ends. The Inv-L usually beat the Inv-V at the same height (~80') on 80-160. In my experience an Inv-L for 160 would be a good choice if one could only have one wire. Tuning is critical for multi-band ops. During this experiment I also had a 2-el horizontal loop for 80 at 55', which was excellent for NVIS and out to ~2500 miles from KL7, and a 1000' horizontal loop at 50-80', which was not worth the effort to build. Today, only the 80 loop and F-12 beam remain at that location. 73, Gary NL7Y ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
[I may have sent an incomplete version of something on this topic. Apologies] 6 dB would be someone's calculation based on currents. The sometimes abysmal performance of a ground rod based vertical system cannot be explained by 6 dB. Cutting my amp from 1500w to 375watts just doesn't get bad enough. Not close. Part of the problem is that we figure all the current in the vertical is free and clear to useful radiation and is not affected by the RF appearance of the ground. You can model a near perfect commercial grade radial field, with a radial system apparent series resistance of a few tenths of an ohm, and NEC4 will still come back with an overall loss of 3 to 4 dB. There is no book-keeping of that loss in the 34 ohm vertical radiator in series with the near zero resistance of the radials, as people typically talk about it. If I run my EZNEC Pro NEC4 3D all points azimuth and elevation run for a gold standard commercial installation, 120 1/4 wave buried radials in average ground, at the bottom of the main window I will get a rather typical 3.9 dB overall loss. IF we have to understand loss as only book-kept in the feed resistance numbers, one would have to APPORTION the 34 ohms resistance to account for the loss. That would be 47 percent in the pattern and 53 percent lost somewhere, by some means, 16 ohms apportioned out to the pattern with 18 ohms of loss somewhere, but not in the radials and not in the vertical wire. Great radials. Top of the line radials. BUT there is still some mechanism draining off 53 percent of the power. The math in NEC 4 is doing and sensing something that explains loss not book-kept in our all-loss-is-shown-in-the-feed Z mental picture. Where's the loss, loss that does not change the feed Z as it comes and goes. How does it work? Can this non-Z-changing loss increase without the commercial radials and a wire fed right at the ground? One could picture my installing a really good antenna at a place looking at a fairly distant horizon. However, I could have trucks and bulldozers built a 1000 foot high dirt wall encircling my place a mile away, and my feed Z would not change. The wall would just soak up RF that otherwise would be out doing wonderful things at low angles. How much additional does unshielded dirt underneath a naked vertical soak up in terms of dB that does not alter the feed Z? Persons unnamed in 1995 recommended two 1/4 wave radials on the ground. I remember that K4CIA from the other side of town, running QRP on his well constructed 160 vertical could often beat me out running 100 watts. What I had was like running QRP on a good antenna. We don't know everything. And there are a lot of people that have awful results with hack job radials. We need to quit recommending hack jobs until we know exactly why they do or do not work, and can explain a FAR greater percentage of the anecdotal material than we can now, and can explain how in some scenarios how we can get results that ARE plainly down 20. If we're not careful, at some point we can be blowing off the essential majority story because we just don't want to listen. 73, Guy On Wed, Dec 12, 2012 at 3:17 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: Correction, 100X the loss. The deal difference between a single ground rod and a BC station ground will be about 6 dB. Dave WX7G On Dec 12, 2012 1:13 PM, DAVID CUTHBERT telegraph...@gmail.com wrote: 20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current max AWAY from the feed point. A quarter wave L on 160 MUST deal with the counterpoise loss issues, one way or another. 73, Guy On Wed, Dec 12, 2012 at 2:07 PM, Ashton Lee ashton.r@hotmail.com wrote: This wonderful article written by L.B.Cebic W4RNL sure can make you a believer in a simple wire inverted L. It is the last antenna discussed. http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf A $3 wire pulled up into a tree will beat just about any commercial antenna… because it is longer. So on low bands it has increased band width and efficiency, and on higher bands it has gain. Yes,
Re: Topband: Fw: GAP VERTICAL QUESTION
On 2012-12-12, at 6:28 PM, Scott MacKenzie wrote: Personally, I use an 80 M loop - I like it especially for stateside contest like Sweep or FD. Nice solid signal on 40M and 80M. By far, the absolute BEST DX antenna that I've ever had the pleasure of using for the low bands is the inverted Bobtail array (40-meters): no radial fields required, super-easy to feed, all-wire construction, bi-directional, stealthy, and---for me, at least---a real band opener on both direct, and long path, circuits... I only wish that I had the wherewithal here to put one up for Topband! I guess it could be done by bending the three vertical elements alright, but I'd still have trouble here attaining even a 60' elevation...(sigh!). ~73~ de Eddy VE3CUI - VE3XZ ___ Topband reflector - topband@contesting.com
Re: Topband: Fw: GAP VERTICAL QUESTION
Guy, here is where I believe your mysterious extra loss in NEC is coming from. You are reading the average gain loss. NEC calculates that by integrating the power at infinity and dividing by the power into the antenna. This accounts for the far-far field ground losses that vertically polarized radiation encounters. But, this is not how we report the radiation efficiency of a vertical. That is defined as the radiated energy in the far field (but not too far) divided by the power into the antenna. Dave WX7G On Wed, Dec 12, 2012 at 4:34 PM, Guy Olinger K2AV olin...@bellsouth.netwrote: [I may have sent an incomplete version of something on this topic. Apologies] 6 dB would be someone's calculation based on currents. The sometimes abysmal performance of a ground rod based vertical system cannot be explained by 6 dB. Cutting my amp from 1500w to 375watts just doesn't get bad enough. Not close. Part of the problem is that we figure all the current in the vertical is free and clear to useful radiation and is not affected by the RF appearance of the ground. You can model a near perfect commercial grade radial field, with a radial system apparent series resistance of a few tenths of an ohm, and NEC4 will still come back with an overall loss of 3 to 4 dB. There is no book-keeping of that loss in the 34 ohm vertical radiator in series with the near zero resistance of the radials, as people typically talk about it. If I run my EZNEC Pro NEC4 3D all points azimuth and elevation run for a gold standard commercial installation, 120 1/4 wave buried radials in average ground, at the bottom of the main window I will get a rather typical 3.9 dB overall loss. IF we have to understand loss as only book-kept in the feed resistance numbers, one would have to APPORTION the 34 ohms resistance to account for the loss. That would be 47 percent in the pattern and 53 percent lost somewhere, by some means, 16 ohms apportioned out to the pattern with 18 ohms of loss somewhere, but not in the radials and not in the vertical wire. Great radials. Top of the line radials. BUT there is still some mechanism draining off 53 percent of the power. The math in NEC 4 is doing and sensing something that explains loss not book-kept in our all-loss-is-shown-in-the-feed Z mental picture. Where's the loss, loss that does not change the feed Z as it comes and goes. How does it work? Can this non-Z-changing loss increase without the commercial radials and a wire fed right at the ground? One could picture my installing a really good antenna at a place looking at a fairly distant horizon. However, I could have trucks and bulldozers built a 1000 foot high dirt wall encircling my place a mile away, and my feed Z would not change. The wall would just soak up RF that otherwise would be out doing wonderful things at low angles. How much additional does unshielded dirt underneath a naked vertical soak up in terms of dB that does not alter the feed Z? Persons unnamed in 1995 recommended two 1/4 wave radials on the ground. I remember that K4CIA from the other side of town, running QRP on his well constructed 160 vertical could often beat me out running 100 watts. What I had was like running QRP on a good antenna. We don't know everything. And there are a lot of people that have awful results with hack job radials. We need to quit recommending hack jobs until we know exactly why they do or do not work, and can explain a FAR greater percentage of the anecdotal material than we can now, and can explain how in some scenarios how we can get results that ARE plainly down 20. If we're not careful, at some point we can be blowing off the essential majority story because we just don't want to listen. 73, Guy On Wed, Dec 12, 2012 at 3:17 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: Correction, 100X the loss. The deal difference between a single ground rod and a BC station ground will be about 6 dB. Dave WX7G On Dec 12, 2012 1:13 PM, DAVID CUTHBERT telegraph...@gmail.com wrote: 20 dB implies that the ground system loss is 10X the inverted-L radiation resistance. This would result in an input resistance of 250 ohms and a minimum VSWR if 5:1. I don't think that is what the real deal will deliver, do you? Dave WX7G On Dec 12, 2012 12:54 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: With the following caveat: The very sparse and short buried radial systems he is showing are FAR more lossy in practice than shown in his gain tables. Four twenty foot buried radials beneath a 1/4 wave L on 160, could place you down 20 dB. You really can't do that as your 160 meter counter poise and expect decent results. You can end feed the same wire on 80/40/30 meters (full wave worth of wire in the L on 80m) with four buried 20 foot radials and it will be an excellent antenna. This is due to the high Z feed at the ground with current
Re: Topband: Fw: GAP VERTICAL QUESTION
Interspersed. On Wed, Dec 12, 2012 at 7:10 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: Guy, here is where I believe your mysterious extra loss in NEC is coming from. You are reading the average gain loss. NEC calculates that by integrating the power at infinity and dividing by the power into the antenna. This accounts for the far-far field ground losses that vertically polarized radiation encounters. Yes, indeed. But where do those ground losses ACTUALLY start? Why is it that what you call far far ground losses can vary by raising very low feed points small amounts above ground that could not possibly be pattern changing in the distance? What you call far far losses start at the BASE of the antenna IF the lossy dielectric of the earth is NOT effectively shielded by an opposite and equal counter-field supplied by dense radials (why proper radials are best). This is a kind of loss that Roy Lewallen terms underestimated in NEC4. If one understands that the losses to ground in the distance start at the end of a dense radial field, and beyond that point manage to lose 3.9 dB for a 1/4 wave system, then what happens to the level of loss when the radius or density of the shielding effect is reduced. What if the shielding extent and density is reduced to NOTHING by use of a ground rod as a counterpoise? When all of this was being shaken out, nobody with money was carefully calculating the Sommerfield ground estimation method for a BC tower connected to a ground rod, or ten foot radials. Gotta remember all that stuff was NOT written for hams, NOT written for us and our faint imitations of proper commercial solutions. NEC is just not calibrated for a lot of the stuff that we try over really dreadful dirt. We're just hoping that the extrapolation down into too-small attempts holds. The extrapolation seems to have some severe problems. But, this is not how we report the radiation efficiency of a vertical. That is defined as the radiated energy in the far field (but not too far) divided by the power into the antenna. Doesn't a term such as radiated energy in the near far field have to run in lock step via formula with the EZNEC loss figure? Using mV/m figures at a mile or a kilometer is FAR, isn't it? And if it doesn't track, is the term worth anything for real application? The range of the integration is the same for both processes, and with one degree points in EZNEC the difference should be way down in the decimal points. And are you saying that the 3.9 dB out there isn't actually lost, that it's really there somehow because its not seen in something called radiation efficiency? The experience says that the loss is there, and the bulk of anecdotal material says the loss can be worse than calculated. I'm just saying that we mark as risky, possibly really bad, anything not reasonably close to full size, dense and uniform all around, or not specifically designed to operate without commercial radials with specific attention to minimization of ground induction from counterpoise and vertical radiators. Faint imitations of radials are going to cost us loss, and the really unfortunate ones can send us down toward 20 dB. The sooner we figure out exactly why the better. Denial doesn't cut it anymore. RBN is double blind. RBN is essentially verifying the anecdotes rather than contradicting them. 73, Guy. Dave WX7G On Wed, Dec 12, 2012 at 4:34 PM, Guy Olinger K2AV olin...@bellsouth.netwrote: [I may have sent an incomplete version of something on this topic. Apologies] 6 dB would be someone's calculation based on currents. The sometimes abysmal performance of a ground rod based vertical system cannot be explained by 6 dB. Cutting my amp from 1500w to 375watts just doesn't get bad enough. Not close. Part of the problem is that we figure all the current in the vertical is free and clear to useful radiation and is not affected by the RF appearance of the ground. You can model a near perfect commercial grade radial field, with a radial system apparent series resistance of a few tenths of an ohm, and NEC4 will still come back with an overall loss of 3 to 4 dB. There is no book-keeping of that loss in the 34 ohm vertical radiator in series with the near zero resistance of the radials, as people typically talk about it. If I run my EZNEC Pro NEC4 3D all points azimuth and elevation run for a gold standard commercial installation, 120 1/4 wave buried radials in average ground, at the bottom of the main window I will get a rather typical 3.9 dB overall loss. IF we have to understand loss as only book-kept in the feed resistance numbers, one would have to APPORTION the 34 ohms resistance to account for the loss. That would be 47 percent in the pattern and 53 percent lost somewhere, by some means, 16 ohms apportioned out to the pattern with 18 ohms of loss somewhere, but not in the radials and not in the vertical wire. Great radials. Top of
Topband: Fw: GAP VERTICAL QUESTION
The GAP Voyager is not much better than a dummy load on 160m. On 80m and 40m it received fairly well compared to my other 80 and 40 antennas. Doug Original Message- With the prospect of downsizing and moving into senior housing in the future I am starting to look at vertical antennas that will allow me to continue A friend of mine had a GAPvertical which covered 160. It did not get out at all. Not as good as a dummy load! Price W0RI ___ Topband reflector - topband@contesting.com
