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80m Vertical over lossy soil
Following is a posting similar to what I made on QRZ.com in reply to a guy who
was asking what kind of antenna to use out west in the mountains surrounded by tall pines. It summarizes my recent experiences with a vertical on 80 m here in central New Jersey: Often you will hear the advice "Use a vertical. You will get the low angle of radiation which you need for DX." Be very careful. Although this statement may be true, you could still be disappointed, especially if you are surrounded by trees, and being in the mountains, might have poor soil, which is necessary for good vertical performance. I speak from experience. I have been building and improving my 80 meter vertical recently, with disappointing results. It is a full size quarter wave wire vertical, hung from a rope that goes from my 72 ft tower to a tree. I have 18 radials, 60 feet long. Now that is a pretty good vertical, with no loading coils, with not very much that can be done to improve it except maybe double the number of radials. I am located in central New Jersey on sandy soil. I have used this antenna for the past several weeks, mostly checking it out on DX. In no case has the vertical beaten out the inverted vee at 60 feet. In nearly every case the antennas are virtually identical. Even on DX to VK6 during CQWW this vertical should be kicking major butt, but it is not. Ok, so a few days ago I modelled both antennas with 4NEC2, and I made sure to include the appropriate parameters in the model for my soil conditions (poor). And I overlaid both antenna patterns on the same chart. Voila! There it is, the inverted vee beats the vertical at all angles above 10 degrees, and is equal below 10 degrees. The moral of the story, be careful about making assumptions regarding antenna performance without having an A-B switch! And maybe the other lesson to be learned is how meaningful the antenna modeling programs are. So my conclusion is that even though the vertical might have the low angle pattern, the losses in the soil do not allow the advantages to be realized. Phased arrays of similar antennas over lossy soil may show the nice pattern and f/b but the absolute value of gain expected may not be realized. 73 Rick K2XT |
80m Vertical over lossy soil
"Rick" wrote in message ... Following is a posting similar to what I made on QRZ.com in reply to a guy who was asking what kind of antenna to use out west in the mountains surrounded by tall pines. It summarizes my recent experiences with a vertical on 80 m here in central New Jersey: Often you will hear the advice "Use a vertical. You will get the low angle of radiation which you need for DX." Be very careful. Although this statement may be true, you could still be disappointed, especially if you are surrounded by trees, and being in the mountains, might have poor soil, which is necessary for good vertical performance. I speak from experience. I have been building and improving my 80 meter vertical recently, with disappointing results. It is a full size quarter wave wire vertical, hung from a rope that goes from my 72 ft tower to a tree. I have 18 radials, 60 feet long. Now that is a pretty good vertical, with no loading coils, with not very much that can be done to improve it except maybe double the number of radials. I am located in central New Jersey on sandy soil. I have used this antenna for the past several weeks, mostly checking it out on DX. In no case has the vertical beaten out the inverted vee at 60 feet. In nearly every case the antennas are virtually identical. Even on DX to VK6 during CQWW this vertical should be kicking major butt, but it is not. Ok, so a few days ago I modelled both antennas with 4NEC2, and I made sure to include the appropriate parameters in the model for my soil conditions (poor). And I overlaid both antenna patterns on the same chart. Voila! There it is, the inverted vee beats the vertical at all angles above 10 degrees, and is equal below 10 degrees. The moral of the story, be careful about making assumptions regarding antenna performance without having an A-B switch! And maybe the other lesson to be learned is how meaningful the antenna modeling programs are. So my conclusion is that even though the vertical might have the low angle pattern, the losses in the soil do not allow the advantages to be realized. Phased arrays of similar antennas over lossy soil may show the nice pattern and f/b but the absolute value of gain expected may not be realized. 73 Rick K2XT It would be interesting to see what 4NEC does if you raise the feedpoint, and centers of the radials, about 10 feet. Tam/WB2TT |
80m Vertical over lossy soil
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80m Vertical over lossy soil
On Nov 6, 4:27 pm, (Rick) wrote:
So my conclusion is that even though the vertical might have the low angle pattern, the losses in the soil do not allow the advantages to be realized. Phased arrays of similar antennas over lossy soil may show the nice pattern and f/b but the absolute value of gain expected may not be realized. 73 Rick K2XT I saw pretty much the same thing. If you want truly top notch performance ground mounted, you have to lay out the wire. Well, unless you are at the beach or something.. :/ I ran mostly 40m using full size verticals, and even with 32 full length radials, I saw mediocre results at best. And I'm on a high rated ground as far as conductivity. When I elevated the antenna to 36 ft at the base is when I finally saw decent performance. Of course, it's not going to be easy to run a full size elevated ground plane on 80m.. :( The only way you are going to see the performance you should is by coughing up more wire. :( But according to some I read, 60 will do the trick rather than having to do the full blown 120.. Not a whole lot of difference between the two in theory. Even elevated at 1/8 wave, a ground plane needs appx sixty radials to equal a ground plane at 1/2 wave , using four radials. And about 120 may well be needed if you really want to equal the losses of the high ground plane. Ground clutter can be another problem, although usually not huge. But, it's just another reason why I prefer an elevated vertical if at all possible. As far as the modeling, I have to adjust the programs to "very good" ground to have it equal what I see in the real world at this QTH. If they are set to default "average" ground, the verticals get shortchanged. :( But on the other hand, maybe that just tells me the ground here is better than average, which actually it is... :/ I'm on the gulf coast, and most of the area rates a "30" on the conductivity maps. Thats no sure thing though.. Even though the ground is decent here, I never had better than mediocre results using a ground mounted vertical with 32 full length radials. I had very good results with the 36 ft high ground plane though. Was like day and night.. MK |
80m Vertical over lossy soil
You are simply comparing two verticals. I don't see why you say that. One is mounted on the ground with 16 radials, the other is simply 2 pcs of wire up 60 feet, with 120 degree included angle in my example, although I can change the angle just by typing over top of the 120 I can make it anything I want. My point was, a lot of people think that if they put up a vertical, even taking care to put a good radial field under it, and they get a low angle of radiation, they have the ultimate single element DX antenna. In fact, when you take losses into consideration a simple inverted vee beats it at all angle over 10 degrees and equals it below 10 degrees. I think that is a pretty significant statement. Rick K2XT |
80m Vertical over lossy soil
Rick wrote:
. . .The moral of the story, be careful about making assumptions regarding antenna performance without having an A-B switch! . . I'd like to add, use receiving signal strength for comparison. I have a friend who occasionally entertains himself by asking for comparative reports for two antennas. The differences are sometimes striking, especially if the two antennas are described as being very different. But in reality they're the same antenna. There are at least two other good reasons for using received signals for comparison. First, you can average out the effects of QSB, which can be tens of dB, and can be different or even opposite for two different antennas. And second, you can, with a step attenuator or an S-meter calibrated with a step attenuator, accurately tell just how great the difference is. If someone else truthfully reports a two S unit difference, you don't have any way to know whether it's 4 dB or 12. Roy Lewallen, W7EL |
80m Vertical over lossy soil
Rick wrote:
In fact, when you take losses into consideration a simple inverted vee beats it at all angle over 10 degrees and equals it below 10 degrees. The average gain of a 1/4WL vertical monopole with ground-mounted radials is in the ballpark of 0 dB in all directions. The average gain of a horizontal 1/2WL dipole is in the ballpark of 6 dB in two directions. It is extremely difficult, if not impossible, for a vertical monopole to achieve 6 dB gain in any direction. It is extremely difficult, if not impossible, for a horizontal dipole to achieve 0 dB gain in all directions. Comparing omnidirectional antennas to directional antennas is like comparing apples and oranges. Decide which characteristics are desirable and erect whatever antenna works best for you. Hint#1: A five-element Yagi makes a lousy net control antenna. Hint#2: A monopole with 120 radials has a lousy front-to-back ratio. -- 73, Cecil http://www.w5dxp.com |
80m Vertical over lossy soil
On Nov 6, 6:05 pm, (Rick) wrote:
My point was, a lot of people think that if they put up a vertical, even taking care to put a good radial field under it, and they get a low angle of radiation, they have the ultimate single element DX antenna. In fact, when you take losses into consideration a simple inverted vee beats it at all angle over 10 degrees and equals it below 10 degrees. I think that is a pretty significant statement. Rick K2XT The only thing is 16 radials is not really what I'd call a good radial field. After what I saw here, I don't even consider 32 radials as a very good radial field.. But when I elevated the antenna I did the see good DX performance. It greatly lowers the ground losses to the point just a few radials will do the job. It smoked my dipole on long paths. And as Roy says, I use mainly the receiver to check, and also I do use an A/B switch.. But I also got plenty of checks on my signal, and of course they matched the margins I saw on receive. My dipole was not at 60 ft, but at 36 ft. But to VK land the GP always beat the dipole by 4 S units. And I really doubt raising my dipole to 60 ft would have been enough to even the score. In theory, the ground losses of my GP at 36 ft with four radials should have been appx equal to a ground mount with 60 radials. This on top of the decent ground conditions. But I also have the advantage of having a clear shot at the horizon with no clutter in the way. I know the ground/space wave greatly increased when I elevated the vertical. I could work ground wave on 40m about 90-100 miles or so. Nearly half way from Houston to San Antonio. I'd be lucky to do 20 on the dipole. But another thing... And this may surprise you.. My 40m mobile antenna is better than my 36 ft high dipole at night if the path is over 800-1000 miles.. Tested it many times to make sure it wasn't a fluke. I don't know how it would fare on 80m to dx vs the dipole.. Never really tested it. I really don't work that much dx on 80m for some reason.. I'm usually working NVIS.. MK |
80m Vertical over lossy soil
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80m Vertical over lossy soil
On Wed, 7 Nov 2007 00:51:07 -0500, "Stefan Wolfe"
wrote: A third antenna, not discussed here, would be a real 1/4 W monopole that is truely connected to earth ground and uses no radial conductive elements. Here, the monopole functions as a dipole but 1/2 of the radiation pattern exists as a mathematical image reflecting against true ground (not a good conductor of electrons like radials, merely a zero voltage reference point). This confused example attempts to pull together disparate characteristics for using ground/radials by extending the problematic metaphor of an antenna image. It takes very little effort to answer all objections raised by this confusion, but it takes very much effort to implement the solution to this confusion that is the answer = push the radials out to the radio horizon. Anyway, the confused example has no bearing on my preceding responses; the two, the vertical and the vee (as described) are poor performers below 10 degrees. 73's Richard Clark, KB7QHC |
80m Vertical over lossy soil
Stefan Wolfe wrote:
. . . A third antenna, not discussed here, would be a real 1/4 W monopole that is truely connected to earth ground and uses no radial conductive elements. Here, the monopole functions as a dipole but 1/2 of the radiation pattern exists as a mathematical image reflecting against true ground (not a good conductor of electrons like radials, merely a zero voltage reference point). Although the mathematical image seems to only exist in theory, the observed physical effects of RF transmission follows the rules of energy conservation and the antenna transmits real RF that can be measured as if it were a true vertical dipole antenna. Now you have seen the real evidence that the host is the true body of Jesus Christ! ...the radials were simply a false religion. The phantom/true earth side of the dipole in the 1/4W monopole ground plane similuates a real metal conductor, mathematically and physically. The only advantage here is that the grounded monopole is 1/2 the height of the full metal conductor dipole. Unfortunately the Earth is largely covered with dirt. It's unclear to me how you "truely connect" to it. Radials provide the lowest loss "connection", but you seem to know of a better way. Please describe it for us. Even if you could make a zero-loss connection to ground (and a large radial field comes close enough for nearly all practical purposes), that dirt still doesn't provide the "mathematical image" of a perfect ground plane. The net effect of the ground's finite conductivity is that the low angle part of the radiation is absorbed in the dirt, heating the earthworms and resulting in a radiation pattern that doesn't resemble a free-space dipole (or monopole over a perfect ground) very closely at all. These effects can be clearly seen with any modern modeling program including the free EZNEC demo. Example file Vert1.ez uses a "MININEC-type" ground which does provide a zero resistance "connection" to ground, something you can approach but not completely accomplish in practice. Compare the pattern of this model to the same one with a perfect ground (superimpose the two on the 2D plot so they're drawn to the same scale) to see how poor an approximation dirt is to a perfect image plane. Interestingly, whereas radials simulate (very inefficiently) a true ground system, a true ground system simulates that which the radial system cannot achieve very well, but both attempt to acheive the same end. One is ground, the other is more like a counterpoise or misplaced antenna element for a balanced antenna. I don't understand that at all. But as you pointed out a while back, I'm a ham with an American Extra Class license, so I know I can't be expected to understand anything very complicated. (Worse yet, I took the exam 44 years ago, so 9/10 of what I knew then is obsolete, and I've forgotten the rest.) Roy Lewallen, W7EL |
80m Vertical over lossy soil
"Cecil Moore" wrote
The average gain of a 1/4WL vertical monopole with ground-mounted radials is in the ballpark of 0 dB in all directions. It is extremely difficult, if not impossible, for a vertical monopole to achieve 6 dB gain in any direction. ____________ Zero or six decibels with respect to what reference, Cecil? If that reference is an isotropic radiator, then note that a typical 1/4-wave monopole and buried radial ground system used by commercial, non-directional AM broadcast stations has an h-plane gain of about 5 dBi. This value has been confirmed by thousands of groundwave field strength measurements of such systems going back 70+ years. Also note that the gain of this monopole over a perfect, infinite ground plane would be only 5.15 dBi, so a broadcast radiator is quite good indeed. And -- a gain of more than 6 dBi is produced by broadcast monopoles whose height exceeds 1/4-wave sufficiently. For example, the h-plane gain of a 1/2-wave broadcast monopole system is about 6.6 dBi (6.8 dBi over a perfect ground plane). RF |
80m Vertical over lossy soil
Stefan, do you have those religious fantasies often? You know we do have drugs now, that cure those.... Drugs are preferred over the old tried and true cure, which involved piles of dry wood, pubertal girls, and combustion... Anyway; Hey I enjoyed your discussion... Now back to the task at hand... Rick, to improve DX performance on a quarter wave vertical over a reasonable radial field I have to go to a dipole at 100 feet, or to one of the high inverted vees, 120 & 150 feet.. While I no longer have a horizontal antenna below 100 feet for 80, when I did the quarter wave vertical shone on DX compared to the lower horizontal antennas.. Secondly, 18 radials just will not do it when you care to send the very best hallmark... An absolute minimum of 30 is needed, and for long dx 50+ is going to be neeeded... By the time you have the radial count up to the 50-60 range you have pretty well maxed out any major improvements until you surpass a 100... Now, there are those who like elevated radials Christman and those who hate em Rauch.. I have to say that my personal experiences on 160 is that 10 or 12, 1/4 wave and tuned, elevated radials works - but they are a pain to keep in the air (in the woods), and tuned, and working... I worked Heard Island with the elevated array on 160... My current 160 ground mounted vertical array has well over a hundred radials of varying lengths and seems to work (G3 from the black RF hole of Michigan on 100 watts while the amp was warming up two nights ago, so it plays reasonably well) Now a dipole or vee at 130 feet is simply not going to work on 160, period... Oh yeah, you can wow the guys at 700 miles with your NVIS signal, but you will get trampled in a dx pileup... So bottom line, even on 80, is that you need to either go to an elevated array as others suggested, or you need to improve your ground radial count - at which point the vertical will shine over a low vee at 1000 + miles... Roy, similarily in my profession; I know that half of everything they taught me is wrong, they just won't tell me which half! cheers |
80m Vertical over lossy soil
Richard Fry wrote:
"Cecil Moore" wrote The average gain of a 1/4WL vertical monopole with ground-mounted radials is in the ballpark of 0 dB in all directions. It is extremely difficult, if not impossible, for a vertical monopole to achieve 6 dB gain in any direction. Zero or six decibels with respect to what reference, Cecil? Sorry, I had a senior moment - should have been dBi. If that reference is an isotropic radiator, then note that a typical 1/4-wave monopole and buried radial ground system used by commercial, non-directional AM broadcast stations has an h-plane gain of about 5 dBi. This value has been confirmed by thousands of groundwave field strength measurements of such systems going back 70+ years. Also note that the gain of this monopole over a perfect, infinite ground plane would be only 5.15 dBi, so a broadcast radiator is quite good indeed. I was speaking of the typical ham radio 1/4WL monopole. EZNEC's VERT1.EZ is an example of such an antenna with a maximum gain of about 0 dBi. The point was that the average 1/4WL amateur monopole doesn't equal the maximum gain of an average 1/2WL dipole, much less the gain of a more directional antenna. -- 73, Cecil http://www.w5dxp.com |
80m Vertical over lossy soil
"Roy Lewallen" wrote
Even if you could make a zero-loss connection to ground (and a large radial field comes close enough for nearly all practical purposes), that dirt still doesn't provide the "mathematical image" of a perfect ground plane. ___________ Expanding on this for S. Wolfe, even if a point connection having zero resistance to earth potential existed at/near the base of a vertical monopole, a monopole using that ground reference would be a poor radiator. This is because the r-f ground currents that need to flow back into the antenna system first would need to travel through the lossy earth from distances up to 1/2 wavelength from the monopole, to reach that perfect ground connection. The function of the buried radials is to provide a low-resistance path for those ground currents, which means that they have to be collected as closely as possible to their sources in the earth (eg, within a disc having a radius of 1/2-wavelength around the monopole). A benchmark field study in 1937 by Brown, Lewis and Epstein of RCA showed that about 120 buried radials each at least 1/4-wave long enable a groundwave field to be radiated by a monopole that is within a few percent of that over a perfect ground plane. Ground conductivity at their test site was no better than 4 mS/m. Their test frequency was 3 MHz. RF |
80m Vertical over lossy soil
"Cecil Moore" wrote
I was speaking of the typical ham radio 1/4WL monopole. EZNEC's VERT1.EZ is an example of such an antenna with a maximum gain of about 0 dBi. And NEC shows that such maximum gain occurs at some angle above the horizontal plane, maybe 20 degrees? NEC also shows zero relative field in the horizontal plane, and very low values below elevation angles of 10 degrees or so. But note in the graphic linked below that for broadcast stations using 1/4-wave monopoles, nighttime skywave coverage in the range of 400 to 1,000 miles is provided by radiation in the range of 1 to 20 degrees elevation. Both theory and practice show that monopole radiation for these conditions could not be as given in a NEC analysis showing the field at an infinite distance. http://i62.photobucket.com/albums/h8...ermanFig55.jpg The point was that the average 1/4WL amateur monopole doesn't equal the maximum gain of an average 1/2WL dipole, It could get very close to it though, with the necessary buried radial system. RF |
80m Vertical over lossy soil
So my conclusion is that even though the vertical might have the low angle
pattern, the losses in the soil do not allow the advantages to be realized. Phased arrays of similar antennas over lossy soil may show the nice pattern and f/b but the absolute value of gain expected may not be realized. My experience in MS (clay soil) comparing a dipole (nearly flat-top) at about 90 feet to verticals is that the verticals nearly always win for dx. (this is on 3.5 MHz). However, I usually put down ~50 1/4-wave radials for the verticals. I would definitely increase the number over 18. My qth is also surrounded by a large number of large pines. In fact the verticals I compare to are wires supported by the trees. I have no idea how much they affect the signal, but verticals still outperform dipoles for dx at my qth. Do you have other metal objects or ground clutter (houses, etc) near to the vertical? What was the feedpoint impedance of the vertical? Tor N4OGW |
80m Vertical over lossy soil
On Nov 7, 6:24 am, Denny wrote:
Now, there are those who like elevated radials Christman and those who hate em Rauch.. Dunno..I can't remember W8JI using elevated verticals.. He may be seeing a large number of people that run elevated, but don't use enough radials for the height in wavelength. Most don't, and then wonder why they don't play as planned.. :( Most 160m elevated verticals are still going to be low to the ground as far as wavelength. Sixty feet is only 1/8 wave. To equal a GP at 1/2 wave requires appx 60 radials. This also equals 120 radials on the ground. 1/4 wave up requires appx 8-10 or so radials to equal the same ground loss. On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. At such a low height in WL, they need almost as many as a ground mount. On 160m, a ground mount is really more practical as everything is large. It will be a lot easier to plant 60+ radials on the ground than it will be to raise the vertical to a decent height. This might apply to 80m also for most people.. But on 40m, it's not hard to set up a decent GP, and my 32 ft whip was fully self supporting. Now a dipole or vee at 130 feet is simply not going to work on 160, period... Oh yeah, you can wow the guys at 700 miles with your NVIS signal, but you will get trampled in a dx pileup... Heck, W8JI ran a 160m dipole at 300+ ft.. The verticals still won as a transmit antenna to DX. I think he uses 60 radials, unless he's added more since that time. I forgot what his vertical is.. A tower of some fairly tall height... It ain't no typical ???? brand multiband dummy load on a stick... :/ MK |
80m Vertical over lossy soil
wrote
On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. At such a low height in WL, they need almost as many as a ground mount. __________ You may be interested in the paper linked below, which reaches a very different conclusion, verified by field experience. NEC models of this system in the broadcast band with the radials elevated 20 feet show gains equal to those using a classic broadcast buried radial ground system. And if this true in the broadcast band, I expect it is true for 160 meters. http://www.nottltd.com/ElevatedRadialSystem.pdf RF |
80m Vertical over lossy soil
On Nov 7, 2:08 pm, "Richard Fry" wrote:
wrote On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. At such a low height in WL, they need almost as many as a ground mount. __________ You may be interested in the paper linked below, which reaches a very different conclusion, verified by field experience. NEC models of this system in the broadcast band with the radials elevated 20 feet show gains equal to those using a classic broadcast buried radial ground system. And if this true in the broadcast band, I expect it is true for 160 meters. http://www.nottltd.com/ElevatedRadialSystem.pdf RF The only problem is I see no direct comparisons to a normal set of buried radials. Only that they were able to meet the "minimums" required by the FCC. I would be curious to see how well the 6 radial setup would compare to a non crippled set of 120 radials. It's interesting, and I'd already seen it, but I'm not really convinced thats it's equal to 120 radials in the ground. Certainly usable though.. I've seen plenty of tests done by amateurs that pretty much swings in the other direction. In fact, being my 40m GP was on a push up mast, I was able to try it with it's four radials, but at lesser heights. It did not work near as well at 1/8 WL, vs it's normal 1/4 WL height. And in terms of wavelengths off the ground, it had an advantage over the 160m scenario. Also, modeling might show them equal, but that still doesn't really convince me until I see it happen in the real world. I've seen a lot of hams have very mediocre results doing pretty much the same thing on 160 and 80. I remember one in particular that got fed up and replace it with a set of normal radials on the ground. Greatly improved his performance. I guess I'm a firm believer in the loss per number of radials vs WL I often quote... :/ So far, I've never seen any indication they are off by any great degree. BTW, I still prefer the elevated vs ground mount. I'm just not as optimistic about the number of radials required to equal 120 in the ground as they are. :/ MK |
80m Vertical over lossy soil
On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. Read Christman... Read Moxon... In general I agree with you but the devil is in the details... denny - k8do |
80m Vertical over lossy soil
Denny wrote:
On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. Read Christman... Read Moxon... In general I agree with you but the devil is in the details... I had a 1/4WL 40m vertical with 8 elevated 1/4WL radials sloping from 20 ft to 5 feet above ground. At no time or distance did the vertical ever beat the one-wavelength dipole in the general directions of the dipole's maximum gain. I assumed it was because the radials were not high enough and not horizontal. -- 73, Cecil http://www.w5dxp.com |
80m Vertical over lossy soil
wrote
The only problem is I see no direct comparisons to a normal set of buried radials. Only that they were able to meet the "minimums" required by the FCC. I would be curious to see how well the 6 radial setup would compare to a non crippled set of 120 radials. It's interesting, and I'd already seen it, but I'm not really convinced thats it's equal to 120 radials in the ground. _______________ The FCC minimums depend on the class of AM station. 1) 362 mV/m/kW at 1 km for Class As (equivalent to 225 mV/m/kW at 1 mile for Class Is), 2) 282 mV/m/kW at 1 km for Class Bs (equivalent to 175 mV/m/kW at 1 mile for Class IIs and Class IIIs), and 3) 241 mV/m/kW at 1 km for Class Cs (equivalent to 150 mV/m/kW at 1 mile for Class IVs). The groundwave field of a perfect 1/4-wave monopole over a perfect ground plane is about 313 mV/m at 1 km for 1 kW of applied power. RF |
80m Vertical over lossy soil
"Cecil Moore" wrote in message et... Denny wrote: On 160m, many think they can elevate a vertical 20 ft or so, and use maybe 4-8-10 radials to get good performance. It just doesn't work that way. Read Christman... Read Moxon... In general I agree with you but the devil is in the details... I had a 1/4WL 40m vertical with 8 elevated 1/4WL radials sloping from 20 ft to 5 feet above ground. At no time or distance did the vertical ever beat the one-wavelength dipole in the general directions of the dipole's maximum gain. I assumed it was because the radials were not high enough and not horizontal. -- 73, Cecil http://www.w5dxp.com This is almost (I had 4 radials) identical to what I once tried on 40. Also had an inverted V at about 45 feet at the same time. In making A/B comparisons with people 300 and 1000 miles away, those with verticals thought my vertical was better; those with dipoles thought the inverted V was better. Go figure. I no longer have the vertical. Tam/WB2TT |
80m Vertical over lossy soil
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