Re: Topband: 2 wl loop, worth the effort? (Rob Atkinson)
I put up an 1100 foot horizontal loop about 6 years ago here in Fort Collins, CO. out in the clear in my back field held up by four 70 foot utility poles spaced about 280 feet apart. Fed by about 220 feet of 450 ohm window line, back to a Palstar BT-1500A true balanced tuner. The loop wire is about 65 feet off the ground I also have a full size vertical for 80M and an inverted L for 160 over a bed of 55 radials 90 feet long fed with 200 feet LMR400. See my QRZ page. There are times when the loop is better or worse than the verticals for 80 or 160 but the comments I have heard seem to go (partially) against what I have experienced with my loop. One example: When FT5ZM was on the air, that DX-pedition is about as far away from my QTH as possible, yet I heard them for between 12-20 minutes every morning and worked them on 160M CW when they were FOUR S units out of the noise (on the 1100 foot loop), speaker copy, no headphones needed! The loop in this case was two S units better than my inverted L and quieter. So, take that as my real world (not computer modeled, not guessed at because I don't have one) experience. Is there some magic at my QTH? No, I don't think so. But as many details I could attend to were done correctly. Is the loop worth the effort? Only you can choose for yourself. My effort was quite a bit of work with huge and heavy utility poles, drilling big holes, putting in 1 ton of concrete per pole, the pulley system to raise and lower the corners, the numerous times I have repaired the feedline connection (we have lots of wind here, up to 100 mph) and all the little details that go along with it. Was it worth it for me? Heck yes. I use it on 160-30M and have verticals for each of those bands as well for when the signal angle and direction or multiple lobes of the loop better suits one antenna over another. 73, Dan W7RF On 12/2/2015 5:54 PM, topband-requ...@contesting.com wrote: 2 wl loop, worth the effort? (Rob Atkinson) _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
I should have written "10 dB or more _additional_ noise." This is a serious problem and is on the radar of the medium wave broadcast industry as well: http://www.radioworld.com/article/afcce-symposium-examines-am-broadcast-band-woes/273098 One other typo: "101 radials, many > 50 feet" should have been 101 radials, many < 50 feet. 73 Rob K5UJ On Thu, Dec 3, 2015 at 6:01 AM, TRM wrote: > 10 dB or more of noise ? Mein Gott ! > > Oh for such a quiet QTH ! > > > 73 - Mort, G2JL _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
10 dB or more of noise ? Mein Gott ! Oh for such a quiet QTH ! 73 - Mort, G2JL _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
I apologize if I ticked anyone off; I'm just trying to help hams understand what is needed to get out. This is not directed at any one person. The topic came up and I have an opinion based on experience with what works and what doesn't. If you put up a cloud burner one or more of three things happen: 1. Some guy who can't hear you comes on what sounds like a clear frequency and calls CQ on top of you. If you are okay with that then no problem. But with the elevated noise floor, it is more and more important to do what you can to be audible. The kinds of setups that were FB 50 years ago often don't make the nut now because in many locations 10 dB or more of noise has to be overcome. Hams in other than rural QTHs simply cannot eliminate all of the noise sources. They can null some out but they can not get the noise floor back to like it was in 1970. That ship has sailed. Another characteristic of medium wave is long deep QSB fades. That has to be overcome with power and a good antenna. 2. You hear a big signal and call. No answer, or "Sri OM vy poor copy try later es 73" because there is not reciprocity between tx and rx with a single antenna on medium wave like there is on HF. 3. You may swear up and down you only want to work locals with your cloud burner but I'd be rich if I had a buck for every ham who calls me from 500 miles away with a "local" antenna. I would like to have a QSO but spending an hour digging out a signal is not my idea of a good time. But, an inverted L has some cloud burner property owing to part of the antenna being horizontal. You can have your cake and eat it too. By the way, I am on a 50 x 100 foot lot in a small city. Antennas are inverted L with 101 radials, many > 50 feet long and an InLogis Pixel Loop antenna. 73 Rob K5UJ _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
You said "Compared to a vertical, there could be 10-30 dB difference in favor of a low dipole (less than 150 ft high) within a few hundred miles.", and I was pretty much trying to make the same point but indirectly since I don't have a dipole on 160 meters. The original poster mentioned relatively short distance work on 160 meters, and that is why I mentioned that a true vertical may not actually be his best choice (he might actually go backwards in performance if he is trying to work stations in adjacent states as an example). I've done hundreds or thousands of tests. I was test crazy when I moved here. Within around 100-200 miles, at night, the verticals and a dipole up about 1/2 wave are really dead compared to a "low" dipole. That problem rapidly vanishes with increased distance, and during daytime skip zone of the high dipole moves in closer. From my house the skip zone of a 280 ft high dipole is about 10-50 miles. The vertical never really has a skip zone in the daytime. Groundwave fills it in. I initially thought a low dipole (or a high dipole) was worth it, but I outgrew that. I just live with the weaker signal in the skip zone. The vertical does so much better at most distances most of the time it is just not worth worrying about. If I wanted to work 50-200 miles, I'd probably just use a low dipole. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Thanks for all the replies, guess the consensus is it is not worth the effort to put up a 2wl loop over a 1wl. I know several mentioned verticals but I really was interested in the loop option. This is for QSO's with stations 500-600 miles from me, currently they report that my signal is strong and very consistent with the 25' high dipole believe it or not. But the dipole is fed with coax and has a limited bandwidth. I am switching to ladder line and was thinking the loop may be the next evolution. I also could move the dipole back to get it up to about 50' and feed it with ladder line as an option. My height is limited to what I have for trees. No tower planned for the new QTH since we are in hurricane/coastal storm country. As far as a receive only antenna that is in the plans soon. Gary Mitchelson NC3Z/4 Pamlico County, NC FM15 On 01-Dec-15 22:00, NC3Z Gary wrote: > I have been contemplating a sky loop to replace my coax 160/80M fan > dipole. The loop would be fed with ladder line so I could use it on 160-40M. > > It would take a bit more effort clearing an area to get up 2wl of wire > but it could be done. Is the effort worth it over a 1wl loop? An > additional issue is I can only get it up about 50'. > > Right now the dipole is at 25' and works very well with the hams I daily > keep in touch with in the 500-600 mile range, but is limited in it's > bandwidth. > > > Gary Mitchelson > NC3Z/4 Pamlico County, NC FM15 > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Hi Tom, You said "Compared to a vertical, there could be 10-30 dB difference in favor of a low dipole (less than 150 ft high) within a few hundred miles.", and I was pretty much trying to make the same point but indirectly since I don't have a dipole on 160 meters. The original poster mentioned relatively short distance work on 160 meters, and that is why I mentioned that a true vertical may not actually be his best choice (he might actually go backwards in performance if he is trying to work stations in adjacent states as an example). Don (wd8dsb) On Wed, Dec 2, 2015 at 3:04 PM, Tom W8JI wrote: > You are misinterpreting the model data by looking at the shape of the >> pattern rather than the relative strength of the pattern at angles of >> interest. Example -- the so-called "take off angle" simply shows the >> vertical angle where the signal is the strongest. FAR more important to >> look at the field strength at various angles as the height is varied. >> > > Many people talk about and look at TOA, and it causes them to pick > antennas that are actually worse just because the TOA is at the correct > angle. :) > > If you look at a low dipole, it has just about the same gain as a low > loop. Being a loop helps moderate impedance on harmonics, but not much else. > > I have 300 ft of height here. For the most part, a vertical did as well or > better than a dipole at any height and distance. The exceptions were at > sunrise or in magnetic storms, or within 50-200 miles (where a dipole below > 150 feet works much better). Compared to a vertical, there could be 10-30 > dB difference in favor of a low dipole (less than 150 ft high) within a few > hundred miles. > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Kevin - I'm in a more tenuous position with Rob than you!!! I operate QRP on 160 you can bet if Rob gets wind of that he'll think I'm REALLY peeing in his Wheaties, 'eh 71.5/72 de Jim R. K9JWV From: Topband on behalf of kol...@rcn.com Sent: Wednesday, December 2, 2015 11:48 AM To: Rob Atkinson Cc: topband@contesting.com Subject: Re: Topband: 2 wl loop, worth the effort? Well Rob, if you read Gary's email, you will find that he is interested in communicating "...with the hams I daily keep in touch with in the 500-600 mile range." The loop may be a great antenna for this but not, as you say, so much for DXing. But there is, in my view, a deeper issue here. I t's the "it's just that I get tired of piss weak signals on 160 from hams who seem to think they have an exemption from Mother Nature" theorem. For many of us, compromise is built in to our situation, we are not being obstinate just to pee you off. In my case, I have a 110 X 50 foot property in a residential neighborhood and I am limited to a "T" transmit antenna (40 ft up, 92 ft flattop) and a K9AY RX array in a somewhat noisy neighborhood. So no, I don't hear or TX like those with a more favorable QTH, but I enjoy 160 meters, I have fun and do the best I can with what I have. So if I occasionally call out of time (I try not to) because I don't have the "ears" you do, don't take it personally... 73 Kevin K3OX - Original Message - From: "Rob Atkinson" To: topband@contesting.com Sent: Wednesday, December 2, 2015 12:53:39 PM Subject: Topband: 2 wl loop, worth the effort? Hi Gary, It would make a nice receiving antenna. Let's start with a question: Would you put up a loop for 20 meters that is 6 feet off the ground? Height for horizontal antennas must always be thought of in terms of _wavelength_. There is only one effective transmitting antenna for medium wave, assuming you do not have 200 foot tall supports for stringing up a horizontal wire antenna, and that is some sort of monopole over a good ground system. Period. And good ground system means a lot of radials. A lot. Not 10 or 20. You don't get to cheat on the laws of physics. You have to bite the bullet and do the work. The excited vertical part has options. T, inverted L, or an insulated tower are all fine provided the vertical part is at least 50 feet tall (more is better). Don't take this personally--it's just that I get tired of piss weak signals on 160 from hams who seem to think they have an exemption from Mother Nature. A dead giveaway that a ham is using a low dipole, 20 feet or so, is rapid deep QSB. Even 50 feet is too low. Inverted Vs are worse. the effective height is halfway between the apex height and the height of the ends. A big horizontal loop on transmit does nothing for you but cause more of your RF to get lost to ground coupling. 73 Rob K5UJ _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Try putting a closed reflector wire under a 1 WL horizontal loop. Lay it on the ground or bury. Use insulated wire and size per typical loops…~+5% at design frequency. Experiment by listening to weak signals while opening and closing the ends of the reflector. At our latitude (64N) loops (and Inv-L’s) work well if a full size vert is unavailable. Some have suggested it’s due to our tilted Ionosphere. That’s been my experience on 40-160. 73, Gary NL7Y _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Forget I said all that. I looked at the model and found some possible mistakes. And I don't have any more time now to fix it. 73, Mike www.w0btu.com On Wed, Dec 2, 2015 at 2:35 PM, Mike Waters wrote: > > I have an EZNEC model of a low loop, if someone wants it. > > > On Wed, Dec 2, 2015 at 2:25 PM, Mike Waters wrote: > >> Model a low 1-wl loop, and you'll see why it was quieter. >> >> 1. There's not quite as much low-angle response. Most local noise comes >> from very low angles. >> 2. More ground loss. >> >> 73, Mike >> www.w0btu.com >> >> On Wed, Dec 2, 2015 at 2:07 PM, wrote: >> >>> two years of playing on 160 the 1 wave length loop was quieter but didnt >>> have the coverage of the dipole, >>> >> >> > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
I should have added that in some types of weather, a dipole may have more corona (which makes noise) off the ends than a loop. I have an EZNEC model of a low loop, if someone wants it. 73, Mike www.w0btu.com On Wed, Dec 2, 2015 at 2:25 PM, Mike Waters wrote: > Model a low 1-wl loop, and you'll see why it was quieter. > > 1. There's not quite as much low-angle response. Most local noise comes > from very low angles. > 2. More ground loss. > > 73, Mike > www.w0btu.com > > On Wed, Dec 2, 2015 at 2:07 PM, wrote: > >> two years of playing on 160 the 1 wave length loop was quieter but didnt >> have the coverage of the dipole, >> > > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Model a low 1-wl loop, and you'll see why it was quieter. 1. There's not quite as much low-angle response. Most local noise comes from very low angles. 2. More ground loss. 73, Mike www.w0btu.com On Wed, Dec 2, 2015 at 2:07 PM, wrote: > two years of playing on 160 the 1 wave length loop was quieter but didnt > have the coverage of the dipole, > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
For what its worth Id stick with the dipoles at that height. I tried 1,2 and 3 wave length loops at ~110 ft (vs dipole at 110 ft) and "on the average" the dipole worked the best. This is completely unscientific but two years of playing on 160 the 1 wave length loop was quieter but didnt have the coverage of the dipole, 2 wave length was the worst (noisier that the one wave length and didnt hear as well) the 3 wave length was only up a short time due to a snow storm but it didnt seem to perform any better than the 1 wave length. If I remember correctly odd wave length loops tend to model better than even wavelength loops.?? K7MS/Lake Tahoe On Tue, 12/1/15, NC3Z Gary wrote: Subject: Topband: 2 wl loop, worth the effort? To: "topband@contesting.com" Date: Tuesday, December 1, 2015, 7:00 PM I have been contemplating a sky loop to replace my coax 160/80M fan dipole. The loop would be fed with ladder line so I could use it on 160-40M. It would take a bit more effort clearing an area to get up 2wl of wire but it could be done. Is the effort worth it over a 1wl loop? An additional issue is I can only get it up about 50'. Right now the dipole is at 25' and works very well with the hams I daily keep in touch with in the 500-600 mile range, but is limited in it's bandwidth. Gary Mitchelson NC3Z/4 Pamlico County, NC FM15 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
160m is a band for vertical polarization. www.w0btu.com/160_meters.html I am a happy user of an inverted-L hung from a tree. Those that don't have room for resonant elevated radials like mine can use K2AV's compact counterpoise, or lay as much wire on the ground as your space permits. www.w0uce.net/K2AVantennas.html 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
You are misinterpreting the model data by looking at the shape of the pattern rather than the relative strength of the pattern at angles of interest. Example -- the so-called "take off angle" simply shows the vertical angle where the signal is the strongest. FAR more important to look at the field strength at various angles as the height is varied. Many people talk about and look at TOA, and it causes them to pick antennas that are actually worse just because the TOA is at the correct angle. :) If you look at a low dipole, it has just about the same gain as a low loop. Being a loop helps moderate impedance on harmonics, but not much else. I have 300 ft of height here. For the most part, a vertical did as well or better than a dipole at any height and distance. The exceptions were at sunrise or in magnetic storms, or within 50-200 miles (where a dipole below 150 feet works much better). Compared to a vertical, there could be 10-30 dB difference in favor of a low dipole (less than 150 ft high) within a few hundred miles. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
On Wed,12/2/2015 11:02 AM, Don Kirk wrote: Therefore while I don't disagree that a vertical on 160 meters is a great antenna especially for DX work, for working stations in close it sometimes can be a disadvantage. Based on modeling it looks like a dipole only 15 feet off the ground on 160 meters would perform much better than my vertical for signals arriving at very high angles (as an example). You are misinterpreting the model data by looking at the shape of the pattern rather than the relative strength of the pattern at angles of interest. Example -- the so-called "take off angle" simply shows the vertical angle where the signal is the strongest. FAR more important to look at the field strength at various angles as the height is varied. I did exactly that in an extensive modeling study comparing vertical and horizontal antennas of various heights. While I concentrated my work on 80M and 40M, the results are directly applicable to 160M if heights in feet are doubled from the 80M plots. http://k9yc.com/VertOrHorizontal-Slides.pdf Bottom line -- for 160M, we mere mortals simply can't get a horizontal antenna too high for local QSOs, and higher is better, at least up to 200 ft. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Hi Rob (and gang), I would like to make one point that should be considered in this discussion. A true vertical which is what I use (not an inverted L) on 160 meters is sometimes horrible on 160 meters for skywave that originates from close in (200 miles or less as an example). During contests I sometimes can't hear a station calling me on my vertical since it's deaf to NVIS signals (signals arriving at a very high angle), but when I switch to one of my pennants suddenly I'm hearing the station 18dB to 38 dB over my noise floor (really an amazing phenomena). The pennant RX antenna gain is only 5 dB down on NVIS (for signals arriving directly overhead) compared with the max gain of the pennant which is at 31 degrees above the horizon. In comparison my 68 foot base loaded vertical has a gain of -20 dB or worse for NVIS at an angle 85 degrees or higher above the horizon compared to its max gain at 22 degrees. Therefore while I don't disagree that a vertical on 160 meters is a great antenna especially for DX work, for working stations in close it sometimes can be a disadvantage. Based on modeling it looks like a dipole only 15 feet off the ground on 160 meters would perform much better than my vertical for signals arriving at very high angles (as an example). Therefore depending on Gary's goal, a true vertical on 160 meters may or may not be in his best interest (but an inverted L might be). Just one of the many things to consider. 73, Don (wd8dsb) On Wed, Dec 2, 2015 at 12:53 PM, Rob Atkinson wrote: > Hi Gary, It would make a nice receiving antenna. > > Let's start with a question: Would you put up a loop for 20 meters > that is 6 feet off the ground? Height for horizontal antennas must > always be thought of in terms of _wavelength_. There is only one > effective transmitting antenna for medium wave, assuming you do not > have 200 foot tall supports for stringing up a horizontal wire > antenna, and that is some sort of monopole over a good ground system. > Period. And good ground system means a lot of radials. A lot. Not > 10 or 20. You don't get to cheat on the laws of physics. You have to > bite the bullet and do the work. The excited vertical part has > options. T, inverted L, or an insulated tower are all fine provided > the vertical part is at least 50 feet tall (more is better). > > Don't take this personally--it's just that I get tired of piss weak > signals on 160 from hams who seem to think they have an exemption from > Mother Nature. A dead giveaway that a ham is using a low dipole, 20 > feet or so, is rapid deep QSB. Even 50 feet is too low. Inverted Vs > are worse. the effective height is halfway between the apex height > and the height of the ends. A big horizontal loop on transmit does > nothing for you but cause more of your RF to get lost to ground > coupling. > > 73 > > Rob > K5UJ > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 2 wl loop, worth the effort?
Well Rob, if you read Gary's email, you will find that he is interested in communicating "...with the hams I daily keep in touch with in the 500-600 mile range." The loop may be a great antenna for this but not, as you say, so much for DXing. But there is, in my view, a deeper issue here. I t's the "it's just that I get tired of piss weak signals on 160 from hams who seem to think they have an exemption from Mother Nature" theorem. For many of us, compromise is built in to our situation, we are not being obstinate just to pee you off. In my case, I have a 110 X 50 foot property in a residential neighborhood and I am limited to a "T" transmit antenna (40 ft up, 92 ft flattop) and a K9AY RX array in a somewhat noisy neighborhood. So no, I don't hear or TX like those with a more favorable QTH, but I enjoy 160 meters, I have fun and do the best I can with what I have. So if I occasionally call out of time (I try not to) because I don't have the "ears" you do, don't take it personally... 73 Kevin K3OX - Original Message - From: "Rob Atkinson" To: topband@contesting.com Sent: Wednesday, December 2, 2015 12:53:39 PM Subject: Topband: 2 wl loop, worth the effort? Hi Gary, It would make a nice receiving antenna. Let's start with a question: Would you put up a loop for 20 meters that is 6 feet off the ground? Height for horizontal antennas must always be thought of in terms of _wavelength_. There is only one effective transmitting antenna for medium wave, assuming you do not have 200 foot tall supports for stringing up a horizontal wire antenna, and that is some sort of monopole over a good ground system. Period. And good ground system means a lot of radials. A lot. Not 10 or 20. You don't get to cheat on the laws of physics. You have to bite the bullet and do the work. The excited vertical part has options. T, inverted L, or an insulated tower are all fine provided the vertical part is at least 50 feet tall (more is better). Don't take this personally--it's just that I get tired of piss weak signals on 160 from hams who seem to think they have an exemption from Mother Nature. A dead giveaway that a ham is using a low dipole, 20 feet or so, is rapid deep QSB. Even 50 feet is too low. Inverted Vs are worse. the effective height is halfway between the apex height and the height of the ends. A big horizontal loop on transmit does nothing for you but cause more of your RF to get lost to ground coupling. 73 Rob K5UJ _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
