Topband: Low Dipoles
Well to try and reply to some of the comments . . . (and apologies that I am repeating myself, but clearly some haven't read all my posts on this subject) I'm certainly NOT trying to suggest that a decent Vertical isn't a good DX antenna for 160m. And my own observations certainly show that a decent Vertical is ESSENTIAL to work DX on 80m. To me, that proves that DX Propagation on 80m is almost always quite Low Angle. However, I also believe that most of the "Experts", even those that have written books on the subject, have come down from 80m, and believe that 160m DX Propagation is the same . . . whereas my own experience of working DX on Top band for the past 50 years convinces me that is NOT the case ! I'm pretty sure that it's probably at a kind of Medium Angle most of the time . . . maybe 30 or 40 degrees, due to being reflected between layers, or multi-hop. That's regardless of whether the stations are 3,000 miles, 6,000 miles or 10,000 miles apart. As I have repeatedly stated, I have done hundreds of signal comparisons against various British DXers over the decades with DX Stations, and found that most of the time there is little to choose between my horizontal Half-waves and their Verticals. Maybe it's something unique about this country, the ground, it's position on the globe . . . I really have no explanation. And there's certainly nothing special about my current Dipole. The centre is mounted on a pole on the roof of my house which is 50ft to the top, one end goes to a tree, the other to another building. It's fed with LMR400 and a big choke balun, so no vertical radiation from it. And I have had similar antennas at 6 different QTHs at different ends of England over the past 50 years, all of which have worked much the same. But the whole point is that it's not just these days that I can easily compare my signals against other Gs with DX by using RBN . . . I have done direct comparisons on SSB with hundreds of DX stations for decades. Heck, 25 years ago there was a group of us coming on every morning for months working a bunch of VKs and ZLs on SSB, so it was easy to compare reports. All the other Gs had big verticals with 40+ radials - some had Inverted Ls, a couple had 120ft towers. But they were amazed that I was consistently as good a signal as they were . . . and I was often receiving even better ! And even since starting this discussion on here, I've had lots of direct emails from North American stations telling me that I am consistently as good a signal as the other English DXers (all running Verticals). So perhaps you can understand why I get a little angry when anyone suggests that I am somehow kidding myself, or that the results should be taken with a pinch of salt ! I can't explain why some of you guys get poor DX results using Dipoles . . . I can only recount my own experiences and direct comparisons against people using Verticals. 73 Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
BillyI would guess it's about 50' - 60'.I will measure it when I get a chance. Most of my antennas are to close to each other on a on a slope. You work with what you have. 73 Fred KB4QZH Original message From: Billy Cox Date: 12/18/20 2:46 PM (GMT-05:00) To: Fred Moeves Subject: Re: Topband: Low Dipoles Good Afternoon Fred,Might I ask how close your K9AY loop is to your Inverted L please?Pondering if it is worth doing here, as the spacing will be close.TU!Merry Christmas and Happy New Year,Billy, AA4NU> On 12/18/2020 12:57 PM Fred Moeves wrote:> I really didn't see a big improvement until I went to a inverted L > over a good number of radials.> And the addition of receive antennas.> K9AY loop and Beverages even short Beverages work. _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Hi Roger, Like the others, I never once thought that you were lying. Respectfully, could you please tell us a little more about your dipole, tower, etc.? For example: - How is the dipole oriented? - How is it fed? - Are you near a body of water? - Could there possibly be some vertically-polarized radiation from your installation? - Any other antennas? - I assume that it is a center-fed, λ/2 wire dipole? 73 Mike W0BTU On Thu, Dec 17, 2020, 3:28 PM Roger Kennedy wrote: > > I do take offence at people suggesting that I am somehow lying about the > results I have always had with a 160m Dipole at 50ft ! > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Topband antennas - mine
My 160m antenna history: 1. (1980-1995) from central Ohio loading a 130 ft long qtr wave sloper off a 60 ft tower: Never loaded well, but worked KP4 and a couple others. No Euros or significant DX. ( I was a contester focusing on 10-80m.) So a couple of mults on 160 made me happy. 2. Moved to a deed restricted area in NE Ohio. Played with hidden wire antennas (corner-fed bobtail curtains) for 12-17-20m, in a small backyard adjacent to a golf course with tall trees while the tower and yagis languished in the garage. Started admiring my one tall tree at the rear of the property - a 95 ft tall Buckeye tree. Also saw some similar tall trees along the edge of the golf course. At one point I tried a delta loop between my tree and theirs, just 5 ft from the PL, during the 160m contest. Figured for a couple of days in wintter they wouldnt notice it. Wrong. The day after I put it up, they came knocking, and I had to reel it in. SO I was left with my solitary tree and a weak bow and arrow that could only go up 40 ft. So I went shopping and bought a hunting bow. Practiced shooting a string over the tree and after a few dozen tries, finally gaged the wind properly and made it over the top. But the arrow didnt have enough weight to pull the string down to ground level, so snapped it off and tried again with a small u-bolt clamped across the nose of the arrow. After playing with different weights, I got it over and it slowly came back to earth as I jiggled the string. That was the birth of my first real 160m antenna - a 1/4 wave INV-L. The angle between the wire going up and the wire coming back down was 25 degrees. ( I ran out of property.). I also only had room for two 125 ft radials that ran from the base of the mighty buckeye tree in a generally northerly direction and passed by on either side of the house out towards the front yard, with a couple of bends to keep in on my property.. I added about five other wires of 30-50 ft long to the west, but couldnt do anything much to the south and east due to the close by PL's. When the contest began I warmed up my FT901dm ( 100w) and made a few calls - they all came back pretty quickly! Tried a few CQ's and before long I had major pile ups wanting to work me. I was shocked and happy. So a casual, late entry turned into great fun and 537 qsos. Never heard so many strong sigs on TB before. And I could actually work them quite easily. This was around 2000. And Ive been on 160 ever since. Unfortunately, when we moved to central OH, I couldnt b ring my 95 ft Buckeye tree with me. And homes with large yards and tall trees were impossible to find in our price range. So we settled on a 3 acre lot in the country ( former farm land) with a solitary 30 ft tall walnut tree with enough room to the east, south and west to run the sloper. Apex around 25' up. The rest horizontal back down to 1 ft above ground. I added one ground rod and it loaded up 1:1 Got on 160 and made some contacts. It was working pretty well. I was stunned to work 4X4-LZ-JA that winter with 100w. and five radials. As the years passed, I added a few radials between 30' and 130 ft long depending on the PL. and years later got up to 28 radials before the swr stopped climbing. So I stopped adding them at that point.. Also, over the past ten years that walnut tree grew from 30 to 50 ft tall, so my INV-L is now a 52 ft vertical leg, and 73' or so sloping run down to 15 ft high at the east end. W3HKK now has 9BDXCC and 160m WAS. DXCC = 154 confirmed/179 worked. but the hunt for new ones has slowed down to a trickle. Ive averaged 88-97 DXCC entities worked each year,. for the last five years but not many new ones. Europe is heard almost daily but not much from the Pacific Islands. or Africa with the Covid travel restrictions in force. Maybe next year things will pick up. Perhaps my next antenna improvement might be modifying the sloping wire into a T. I dont think adding more radials would made a major difference in my current INV-L's performance. Thoughts? Bob _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
On 12/18/2020 4:28 AM, Rob Atkinson wrote: I invite you to come to the middle of North America, Nebraska let's say, and set up the exact same antenna in a rural location and report how it performs after a full winter operating season. Or to Northern California, and report on how many EU stations you hear. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Plenty of more experienced operators have already gave their insight. But... here's my 2 cents.. When I started back in the 80s. I first tried Dipole on 160 worked a few local stations out to 200-300 miles. I then tried to load short tower I really didn't know what I was doing so that failed. I then tried a low full wave loop it received well but wasn't any better then the low Dipole. I really didn't see a big improvement until I went to a inverted L over a good number of radials. And the addition of receive antennas. K9AY loop and Beverages even short Beverages work. And a side note just before the weather here in Ky turned bad. I tried a DHDL and could not get it to work. I probably had it to close to my north Beverage. I try again when it warms up. I think you just have to have fun a build a few different antennas and see what works. If I would have had an Elmer back then I might not have tried the Loop or Dipole...Maybe.. Fred KB4QZH On 12/18/2020 10:09 AM, cl...@gm3poi.com wrote: Mike, all antennas work, some better than others, a choice of one maybe not ideal. Without an A/B comparison impossible to judge and I would add if any vertical system is less than a quarter wave high it puts additional pressure on the ground system to be even better. As per Lewis, Brown Epstein. 73 Clive GM3POI -Original Message- From: Topband On Behalf Of Mike Tessmer K9NW Sent: 18 December 2020 14:40 To: topband@contesting.com Subject: Re: Topband: Low Dipoles Sometimes stuff just works. 73, Mike K9NW _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Not so boring report
This morning - the band was in excellent shape from the Pacific Northwest to Europe. I knew things were going to be good when the first signal I heard on the band was from RC3FL and he was 579 at 1337 UTC (a little over two hours before my sunrise). During the next two hours, I was able to put 34 Europeans in my log - including many first time callsigns. This is the best morning opening I have experienced this "cycle" of sunspot minimum. Tree N6TR/7 Manning, OR _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Its a fool's errand to use only antenna modelling software to evaluate the complexity of topband transmitting antenna performance. Why is that? Antenna models do not take into account polarization mismatch loss, a fact of life because the electron gyrofrequency is so close to 160 meters. See K9LA's excellent article: https://k9la.us/Polarization.pdf Antenna models also do not consider the lossy ground reflection in the Fresnel zone in front of the antenna. The Fresnel zone isn't a thin line along the ground in the direction of the distant receiving antenna, rather it has an elliptical shape with significant width. That's why HFTA analysis should always include ray traces at multiple azimuth angles in front of the antenna, unless the reflection zone has uniform terrain, such as several square miles of prairie or seawater. The classic reference on this topic is: https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote139.pdf While the NBS publication primarily addresses horizontally polarized antennas, its general conclusions also apply to topband vertical antennas. More than half of the low angle radiation from a 1/4 wavelength 160 meter vertical is formed in an approximately 500 foot wide zone in the direction of propagation from the transmitting antenna to the intended receiver. The far edge of the Fresnel Zone is several miles away for low angle radiation from a 1/4 wavelength 160 vertical, especially if the vertical is installed on a highly conductive surface such as sea water, salt marsh or wet marshy soil. The far edge of the Fresnel zone is much closer when a 160 meter 1/4 wavelength vertical is installed over poorly conducting dry, chalky or sandy soil. A specific worked example: For a 10 degree elevation angle more than half of the radiation from a 160 meter 1/4 wave vertical is formed in an area approximately 500 feet wide in the desired direction of propagation. The near edge of the reflection zone is approximately 3000 feet in front of the vertical and the far edge is about three miles from the the vertical Its obvious that an extensive radial system has no affect at all of the efficiency of the ground reflection in the Fresnel Zone. Radials affect only the efficiency of the antenna itself. 73 Frank W3LPL - Original Message - From: "K4SAV" To: topband@contesting.com Sent: Friday, December 18, 2020 4:48:20 PM Subject: Re: Topband: Low Dipoles On 12/18/2020 10:18 AM, Mike Waters wrote: > A few words of wisdom about 160m antennas from W8JI, ON4UN and others... > > https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html After you read W8JI's comments, put these two antennas on EZNEC. It will say the dipole smokes the vertical at all elevation angles. I trust W8JI's information because of his experience and his attention to detail when running tests like this. NEC is not telling you the whole story. Jerry, K4SAV _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
On 12/18/2020 10:18 AM, Mike Waters wrote: A few words of wisdom about 160m antennas from W8JI, ON4UN and others... https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html After you read W8JI's comments, put these two antennas on EZNEC. It will say the dipole smokes the vertical at all elevation angles. I trust W8JI's information because of his experience and his attention to detail when running tests like this. NEC is not telling you the whole story. Jerry, K4SAV _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Well said, Clive! :-) On Fri, Dec 18, 2020, 9:10 AM wrote: > All antennas work, some better than others, a choice of one maybe not > ideal. > * Without an A/B comparison impossible to judge* and I would add if any > vertical system is less than a quarter wave high it puts additional > pressure > on the ground system to be even better. As per Lewis, Brown Epstein. 73 > Clive GM3POI 73, Mike W0BTU _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
A few words of wisdom about 160m antennas from W8JI, ON4UN and others... https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html 73 Mike W0BTU _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
I read a comment some while ago that our impressions of what is required for our low bands is distorted by the original works done in the 30s for medium wave broadcast transmitters in USA, in that, broadcast needs are different because they are servicing a "local" population and thus need a high "local" field intensity in day time at least and want to *avoid* dx. So, the short vertical and massive ground systems are de rigueur for those transmitters. In those days it was probably most popular for folks receiving MW broadcasts to use a low horizontal wire. What would be interesting in this discussion would be recorded occasions when a low dipole is used at each end of the QSO. David G3UNA/G6CP _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Mike, all antennas work, some better than others, a choice of one maybe not ideal. Without an A/B comparison impossible to judge and I would add if any vertical system is less than a quarter wave high it puts additional pressure on the ground system to be even better. As per Lewis, Brown Epstein. 73 Clive GM3POI -Original Message- From: Topband On Behalf Of Mike Tessmer K9NW Sent: 18 December 2020 14:40 To: topband@contesting.com Subject: Re: Topband: Low Dipoles Sometimes stuff just works. 73, Mike K9NW _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
Sometimes stuff just works. 73, Mike K9NW _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Low Dipoles
PleaseNebraska would be too easy as the propagation is quite good there. Try central Minnesota and trust me the only EU stations worked will be just a few in mid to late December. This is 50 years of me operating from Minnesota speaking with a rather good 160 transmit antenna. Thank you Rob for the reality check. Merry Xmas Mark K0KX On Fri, Dec 18, 2020 at 6:28 AM Rob Atkinson wrote: > > I do take offence at people suggesting that I am somehow lying about the > > results I have always had with a 160m Dipole at 50ft ! > > I don't think anyone believes you are lying, but perhaps instead, that > you seem to imply that your experience can be generalized and that you > are therefore, misguided. This is because your results run counter to > decades of experience and observations by countless others when it > comes to antennas and 160 meters. I invite you to come to the middle > of North America, Nebraska let's say, and set up the exact same > antenna in a rural location and report how it performs after a full > winter operating season. > > Merry Xmas > Rob > K5UJ > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Low Dipoles
> I do take offence at people suggesting that I am somehow lying about the > results I have always had with a 160m Dipole at 50ft ! I don't think anyone believes you are lying, but perhaps instead, that you seem to imply that your experience can be generalized and that you are therefore, misguided. This is because your results run counter to decades of experience and observations by countless others when it comes to antennas and 160 meters. I invite you to come to the middle of North America, Nebraska let's say, and set up the exact same antenna in a rural location and report how it performs after a full winter operating season. Merry Xmas Rob K5UJ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
