Re: Topband: EZNEC Ground Errors
It's interesting how people's experiences differ, and how their perceptions of how something actually works, and how a computer model calculates how it should work. I have used MMANA-GAL to model designs, and it certainly helps to quantify my measurements, and is a good start. "Your Mileage May Vary" is a great disclaimer, after a system is described! Also interesting is how DXing experiences vary from place to place, for example Roger's situation where he has a high density of activity to his east at medium range in Europe making difficulties, when he's looking for other medium to longer range DX in NA to his west. Those in USA east have a high density of local stations making it difficult to work DX. In VK/ZL most of our wanted DX is quite long range, with very few locals. Consequently, our receiving requirements differ. My first DXing on 160 m was with a 160 m long doublet antenna, up about 20 m supported by trees. That whetted my appetite for the band, and so I constructed a top loaded vertical, over elevated radials. That worked, and I made DXCC. Next, the elevated radials went (then kept falling down anyway!) and I made the effort to bury 2000 metres of wire in 60 x 33 m radials. That appears to work, but I have no way of objectively comparing the elevated radial system to the buried radial system. But one aim of the buried radials, was to have a non-resonant ground radial field, as I also run 80 m over it. Next is to put up a 37 m high tower, so I have close to a quarter wave on 160 m. That is my project for the Christmas break. I'm hoping to have that up and running before the end of the summer DX in the mornings to EU. 73, Luke VK3HJ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: EZNEC Ground Errors
Oh that's something else I forgot to mention . . . A couple of years ago I built a 160m Receiving Loop, which is Vertically polarised. It behaves very differently to my Dipole, I can see huge differences on European signals, depending on how far away they are, and the Propagation at the time. However . . . on DX there is usually no difference between the two antennas (although the QSB is often "out of phase") . . . which again makes me think DX Signals are arriving at a Medium Angle, rather than a High or Low angle. (If they were Low angle they would definitely be stronger on the Loop). And again, this is NOT at Grey Line times . . . it's pretty much all the time, both on TX and Rx. Years ago, when conditions were always much better, I used spend dozens of hours on SSB getting comparison reports from stations right across America with my good friend Mike G3SED. We lived quite close to each other at the time, he had a 100 ft vertical (with 60 radials), I had a Half Wave Dipole. When we were running the same power, most of the time our reports were the same ! These days I have set up RBN to show ALL G stations CW reports from any American station . . . and again I notice that my signals are generally on a par with all the Gs running verticals. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: EZNEC Ground Errors
For a literal "pair of radio wave glasses": Given the vertical gain of a practical 160 dipole is pretty much cloud burner and a decent 160 vertical is pretty much low angle, IF you know the actual real gain patterns, then it is possible to compare signal amplitudes (probably real time considering QSB) and deduce approximate arrival angles. At least one analysis of 80m arrival angles on the West Coast from EU was derived this way. Grant KZ1W On 12/11/2020 06:38, Artek Manuals wrote: OR The propagation mode on 160 is not what we have popularly come to "Accept". There is a growing body of evidence that particularly at gray line that signals often arrive at a higher angles. This is often attributed to "ducting" . Maybe a lot more of 160 intercontinental propagation is due ducting rather than the more commonly thought of low angle earth to F layer hop/multi-hop stuff seen at higher frequencies? Where do i get a pair of those glasses that lets me look at radio waves so I actually see them arrive Dave NR1DX On 12/11/2020 8:58 AM, Roger Kennedy wrote: Guy I have ALWAYS thought that the various Computer-based modelling of Ground and its effect on Antennas is WAY off . . . And surely the errors are MOST significant on 160m, not just because Antennas are near the ground (in wavelength terms) . . . but also because even the ground 130 ft deep is still going to have an effect . . . and there is no way EZNEC can possibly take that into account, even if you KNEW what was underneath your topsoil ! In my particular case it's not the effect on Verticals on 160m that interest me . . . it's the effect on a Low Dipole. Any DX stations I work on 160m will confirm I put out a pretty respectable signal . . . my signal reports around the world and more recently I am able to compare my RBN Reports across NA and they tend to be very similar to the other British DXers. However, most people are surprised to discover that for the last 50 years I have always used a Horizontal Half Wave dipole on 160m, at around 50ft. BUT I believe that EZNEC plots showing that most of the RF is just very High Angle is WRONG . . . that's because in practice the Ground underneath it is rubbish . . . so the Dipole's effective height above Ground is much higher. And in fact, it seems that most people who have Dipoles on 160m mounted over or near a very comprehensive Radial system DO get poor results using them for DX . . . but that goes to confirm my theory (which is all based on my actual experience on Top Band) Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: EZNEC Ground Errors
I have two receiving antennas on 160: an 8-circle vertical array and a low dipole up 10 feet. I have been noticing that in the first part of the evening, the dipole often hears Europe as well as, or nearly as well as, the 8-circle. This appears to indicate that the signals are arriving at relatively high angles. This might also explain why a transmit dipole at a moderate height can work well for DX. Other times, the dipole is way down from the 8-circle, and I would expect a vertical transmit antenna to do better. Occasionally in the mornings, around SR, the dipole also hears the DX as well as or sometimes better than the 8-circle. 73, John W1FV -Original Message- From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf Of Artek Manuals Sent: Friday, December 11, 2020 9:39 AM To: topband@contesting.com Subject: Re: Topband: EZNEC Ground Errors OR The propagation mode on 160 is not what we have popularly come to "Accept". There is a growing body of evidence that particularly at gray line that signals often arrive at a higher angles. This is often attributed to "ducting" . Maybe a lot more of 160 intercontinental propagation is due ducting rather than the more commonly thought of low angle earth to F layer hop/multi-hop stuff seen at higher frequencies? Where do i get a pair of those glasses that lets me look at radio waves so I actually see them arrive Dave NR1DX On 12/11/2020 8:58 AM, Roger Kennedy wrote: > Guy I have ALWAYS thought that the various Computer-based modelling of > Ground and its effect on Antennas is WAY off . . . > > And surely the errors are MOST significant on 160m, not just because > Antennas are near the ground (in wavelength terms) . . . but also because > even the ground 130 ft deep is still going to have an effect . . . and there > is no way EZNEC can possibly take that into account, even if you KNEW what > was underneath your topsoil ! > > In my particular case it's not the effect on Verticals on 160m that interest > me . . . it's the effect on a Low Dipole. > > Any DX stations I work on 160m will confirm I put out a pretty respectable > signal . . . my signal reports around the world and more recently I am able > to compare my RBN Reports across NA and they tend to be very similar to the > other British DXers. > > However, most people are surprised to discover that for the last 50 years I > have always used a Horizontal Half Wave dipole on 160m, at around 50ft. > > BUT I believe that EZNEC plots showing that most of the RF is just very High > Angle is WRONG . . . that's because in practice the Ground underneath it is > rubbish . . . so the Dipole's effective height above Ground is much higher. > > And in fact, it seems that most people who have Dipoles on 160m mounted over > or near a very comprehensive Radial system DO get poor results using them > for DX . . . but that goes to confirm my theory (which is all based on my > actual experience on Top Band) > > Roger G3YRO > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: EZNEC Ground Errors
Well I agree with that too Dave . . . To me, it's a kind of "Urban Myth" that 160m DX is all Low Angle propagation. Sure, on 80m it nearly ALWAYS is . . . You MUST have a Vertical to work DX well on 80, a Dipole is rubbish (even though my 80m dipole is effectively twice as high as my Top Band one) I actually think that many "experts" PRESUMED that because that is the case on 80m (and on 40m), it MUST be so on 160m too. But I know that simply isn't the case, from 50 years of my own experience DX-ing on 160m. And not just at Grey Line either . . . for example, I find my best reports from NA these days are currently between 0100 and 0300Z . . . that is way after your Sunset, and long before our Sunrise. So in practice, I have come to the conclusion that it must be a combination of the two . . . 160m DX isn't very low angle (must be ducting or multi-hop) . . . and a low dipole on 160m isn't just high angle. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: EZNEC Ground Errors
OR The propagation mode on 160 is not what we have popularly come to "Accept". There is a growing body of evidence that particularly at gray line that signals often arrive at a higher angles. This is often attributed to "ducting" . Maybe a lot more of 160 intercontinental propagation is due ducting rather than the more commonly thought of low angle earth to F layer hop/multi-hop stuff seen at higher frequencies? Where do i get a pair of those glasses that lets me look at radio waves so I actually see them arrive Dave NR1DX On 12/11/2020 8:58 AM, Roger Kennedy wrote: Guy I have ALWAYS thought that the various Computer-based modelling of Ground and its effect on Antennas is WAY off . . . And surely the errors are MOST significant on 160m, not just because Antennas are near the ground (in wavelength terms) . . . but also because even the ground 130 ft deep is still going to have an effect . . . and there is no way EZNEC can possibly take that into account, even if you KNEW what was underneath your topsoil ! In my particular case it's not the effect on Verticals on 160m that interest me . . . it's the effect on a Low Dipole. Any DX stations I work on 160m will confirm I put out a pretty respectable signal . . . my signal reports around the world and more recently I am able to compare my RBN Reports across NA and they tend to be very similar to the other British DXers. However, most people are surprised to discover that for the last 50 years I have always used a Horizontal Half Wave dipole on 160m, at around 50ft. BUT I believe that EZNEC plots showing that most of the RF is just very High Angle is WRONG . . . that's because in practice the Ground underneath it is rubbish . . . so the Dipole's effective height above Ground is much higher. And in fact, it seems that most people who have Dipoles on 160m mounted over or near a very comprehensive Radial system DO get poor results using them for DX . . . but that goes to confirm my theory (which is all based on my actual experience on Top Band) Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: EZNEC Ground Errors
Guy I have ALWAYS thought that the various Computer-based modelling of Ground and its effect on Antennas is WAY off . . . And surely the errors are MOST significant on 160m, not just because Antennas are near the ground (in wavelength terms) . . . but also because even the ground 130 ft deep is still going to have an effect . . . and there is no way EZNEC can possibly take that into account, even if you KNEW what was underneath your topsoil ! In my particular case it's not the effect on Verticals on 160m that interest me . . . it's the effect on a Low Dipole. Any DX stations I work on 160m will confirm I put out a pretty respectable signal . . . my signal reports around the world and more recently I am able to compare my RBN Reports across NA and they tend to be very similar to the other British DXers. However, most people are surprised to discover that for the last 50 years I have always used a Horizontal Half Wave dipole on 160m, at around 50ft. BUT I believe that EZNEC plots showing that most of the RF is just very High Angle is WRONG . . . that's because in practice the Ground underneath it is rubbish . . . so the Dipole's effective height above Ground is much higher. And in fact, it seems that most people who have Dipoles on 160m mounted over or near a very comprehensive Radial system DO get poor results using them for DX . . . but that goes to confirm my theory (which is all based on my actual experience on Top Band) Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
