Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Thu, Jan 23, 2014 at 8:00 PM, Richard Fry r...@adams.net wrote: Note that the NEC4.2 analysis I generated and linked at http://s20.postimg.org/6hfsl64ml/Elevated_vs_Buried_Radials.jpg closely replicates the measured results of a real-world monopole system elevated 4.9 meters above the earth. That's interesting because the presentation shows the max of the four elevated at *minus* 1.17, while the buried radials are minus 0.71. That means the 4 elevated are about a half dB inferior to dense buried. Did you run that four elevated model setup with the buried radials in place, but not connected to the feedpoint, just floating, or was it just four elevated over plain ground. What were the ground constants in use when you ran the models? When you say closely replicates, are you comparing the models' groundwave display to field strength measurements at ground? 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
A response to David Raymond's questions on elevated monopole systems was posted to the listserver on Jan 22, 2014 (link below). http://lists.contesting.com/archives//html/Topband/2014-01/msg00189.html _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Guy Olinger wrote: ...the presentation shows the max of the four elevated at *minus* 1.17, while the buried radials are minus 0.71. That means the 4 elevated are about a half dB inferior to dense buried. The text of my post first including the URL for my NEC study (link below) stated that there was about 0.5 dB difference between them because I hadn't taken the time to trim the monopoles heights slightly to produce identical results. But that wasn't necessary to make the point that the system with elevated radials installed over poor earth having no buried radials in it has essentially the same performance as the system using 120 x 1/4-wave radials (only), buried in that same earth. Did you run that four elevated model setup with the buried radials in place, but not connected to the feedpoint, just floating, or was it just four elevated over plain ground. The elevated system was comprised of five conductors, only: the vertical monopole and the four horizontal radials -- as per the wire model shown as an inset in the elevation pattern for the elevated system in my graphic. That elevated system has no metallic connection to the earth, and no other metallic conductors in the model. What were the ground constants in use when you ran the models? As stated in my earlier post linked below, and also in large letters at the top of my NEC study page, it was 1 mS/m, d.c. 5. When you say closely replicates, are you comparing the models' groundwave display to field strength measurements at ground? The inverse distance field intensity for 1 kW of applied power at a distance of 1 km determined by the consultant for WPCI's elevated system closely replicates the inverse distance field expected by the FCC for a 1/4-wave monopole driven against 120 x 1/4-wave buried radials (302 mVm and 307 mV/m, respectively). A perfect 1/4-wave monopole driven against a perfect ground plane produces about 313.6 mV/m at 1 km for 1 kW of applied power. My NEC study shows that the peak gain and radiation pattern of the two systems compared essentially are duplicates. Equal antenna system gains produce equal fields at a given distance, for a given applied power. Note that the basic information needed to answer the questions shown above already was included in my earlier posts. http://lists.contesting.com/archives//html/Topband/2014-01/msg00202.html R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Fri, Jan 24, 2014 at 7:07 AM, Richard Fry r...@adams.net wrote: But that wasn't necessary to make the point that the system with elevated radials installed over poor earth having no buried radials in it has essentially the same performance as the system using 120 x 1/4-wave radials (only), buried in that same earth. ...essentially the same... A scientific definition of that would be interesting. My impression is that I am highly unappreciated by certain folks when I use such terms. An additional half dB loss in the antenna system is a permanent 12% increase in the power bill for the transmitter if one is required to maintain specified field strength. To a station manager that's probably an entirely unsatisfactory increase in moolah drain. With a 10 or 50 kW station, that's a *killer* difference. He would not use the term essentially the same. For some restricted ham situations being down only 1.5 dB from a commercial method reference could easily be as good as is possible, and only 0.5 dB would be wonderful. But for the science, 0.5 dB is simply 0.5 dB, and worthy of accounting. A 0.5 dB here and a 0.5 dB there, and 0.5 dB elsewhere starts to add up to barely catching some DX otherwise not had. And a confirmation is a confirmation. Run the four elevated over the radial field. The buzz I hear on the grapevine about 4 elevated is that's the remedy for a radial field gone sour, of course leaving the old radials *retired in place*. Trying to disprove experience in non-commercial small lot situations by referring to NEC 4.x model runs from the the middle of the commercial MF BC paradigm just won't cut it. I have already stipulated many times that NEC 4 is calibrated for that paradigm and seemingly delivers well documented good results. In the same manner, you can't prove distant low and sky-wave patterns by measuring at the ground or only locally. The small lot experience is that losses to ground are underestimated by NEC 4.x, the underestimation an opinion notably shared by Roy Lewallen, W7EL, author of the respected EZNEC series of NEC shells, who has spent some serious time chasing the issue. I have gone to using .0002,1 (ghastly ground) as ground characteristics for testing model changes for ground sensitivity, giving the worst possible results for non-dense-radial counterpoise designs. This is used for comparing a before model to an after model, with wire or counterpoise changes. This accentuates changes in results due to the way ground is induced. Picking solutions with the least sensitivity to ghastly earth, again and again brings happy results in real world applications which are borne out in RBN changes. While one might think ghastly earth is too severe, difficult urban and concrete-asphalt-ish small lot situations sometimes seem even worse, pointing to some mechanism in play that is unbookept in NEC ground treatment, or possibly undiscovered. Since the NEC ground method is both monolithic characteristics and for essential reasons confined to ground *approximations*, this is really not surprising. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
I'd like to understand how NEC 4 achieves this calibration for MW BC ground systems. Do others share this concern? What errors are introduced for other analysis as a result? Grant KZ1W On 1/24/2014 1:58 PM, Guy Olinger K2AV wrote: I have already stipulated many times that NEC 4 is calibrated for that paradigm _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Guy Olinger postulated for a while, then wrote: ... Run the four elevated over the radial field. ... You posted that you have NEC4, Mr Olinger. Why not do that yourself then, rather than ask someone else to do it for you? Post your results and the bases for them, as I have done for my NEC4 analysis. Your credibility will improve if your accurate NEC model results show that the radiation efficiency of a vertical monopole using four, elevated, 1/4-wave radials when installed concentric with even a perfect set of 120 x 1/4-wave buried radials is significantly better than if those buried radials were not present (other parameters the same). Let us define significant as differing by more than 0.5 dB. The buzz I hear on the grapevine about 4 elevated is that's the remedy for a radial field gone sour, of course leaving the old radials *retired in place*. The grapevine buzz you report about this subject is not worth further dissemination, as no defensible documentation is available to support its accuracy. In any case, monopoles using only several, elevated, 1/4-wave radials have been used by AM broadcast stations where it was impossible/impractical to install ANY buried radials -- and those systems performed nearly as well as if they were driven against a set of 120 x 1/4-wave buried radials (as I posted previously) -- and they met/exceeded the FCC's minimum efficiency requirements for those AM broadcast antenna systems for that class of service. There is no scientific reason why that same result would not apply to ham operators with monopoles on the 160-meter band using ONLY several, elevated, 1/4-wave radials. Or possibly even to those hams using monopoles with only an FCP. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Well, it seems to me, that something that is being overlooked in this discussion, is that for, many of us, buried radials are not an option. In my case, I have bedrock that comes pretty much right up to the surface on much of my lot that's available for antennas, and I have a long concrete driveway, that runs pretty much the full length of my lot to a detached garage that's near my small tower. The point is, that many of us without large amounts of funds or real estate, simply have to accept the reality of our situation and, work with what we have, and try to flower where we're planted. In my case I've worked lots of pretty good DX on all continents and in all the oceans with an inverted L about 75 feet tall and supported by a tall tulip poplar and had two elevated resonant radials, diametrically opposed just above the level of the fence line around my small urban lot here in Raleigh, NC and never more than 500 -600 watts. Some examples on 160, are 3B8, JA, VK, ZL, VK6, ZS6, ZD9.S79, KL7.KH6 ( many) KH5, KH5K, KH7K, KH2, T32 , FO0, LOTs of Europeans. quite a few Africans, Lots of South America, of course. I should point out that from Raleigh, NC VK6 is pretty close to being the antipode. - And I wasn't a SERIOUS 160m op. I was mostly chasing DX on 40 m and working everything that was around on as many bands as possible with my killer 5-band quad. Worked everything on the DXCC country list on CW except for North Korea. But generally, on 160, if I could HEAR 'em, I could work 'em! Biggest problem was hearing!! But the addition of a couple of 40' X 10' KAZ terminated receiving loops helped a LOT!! - a LOT more than another 0.5 DB of TX antenna gain would have afforded. As I said, if I could hear 'em, I could work 'em! An additional 0.5 or 1.0 DB on TX wouldn't have made much difference! And I had fun!! There's a lot to be said for listening a LOT - for catching the DX when they come up and working 'em before the packet-rats show up! In other words, try to be there when and where the competition ain't! And BTW 160 doesn't die in our summer - when it's winter in the Southern hemisphere. There's a lot available on Topband in summer. Just have to listen a lot! Especially in our mornings before and after our sunrise before a lot of the QRN from the T-storms picks up! A lt of VKs, ZLs etc. available then! FWIW! Good huntn' 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard Fry Sent: Friday, January 24, 2014 7:26 PM To: topband@contesting.com Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? Guy Olinger postulated for a while, then wrote: ... Run the four elevated over the radial field. ... You posted that you have NEC4, Mr Olinger. Why not do that yourself then, rather than ask someone else to do it for you? Post your results and the bases for them, as I have done for my NEC4 analysis. Your credibility will improve if your accurate NEC model results show that the radiation efficiency of a vertical monopole using four, elevated, 1/4-wave radials when installed concentric with even a perfect set of 120 x 1/4-wave buried radials is significantly better than if those buried radials were not present (other parameters the same). Let us define significant as differing by more than 0.5 dB. The buzz I hear on the grapevine about 4 elevated is that's the remedy for a radial field gone sour, of course leaving the old radials *retired in place*. The grapevine buzz you report about this subject is not worth further dissemination, as no defensible documentation is available to support its accuracy. In any case, monopoles using only several, elevated, 1/4-wave radials have been used by AM broadcast stations where it was impossible/impractical to install ANY buried radials -- and those systems performed nearly as well as if they were driven against a set of 120 x 1/4-wave buried radials (as I posted previously) -- and they met/exceeded the FCC's minimum efficiency requirements for those AM broadcast antenna systems for that class of service. There is no scientific reason why that same result would not apply to ham operators with monopoles on the 160-meter band using ONLY several, elevated, 1/4-wave radials. Or possibly even to those hams using monopoles with only an FCP. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Guy Olinger wrote: Careful here ... The presence of 0.4 wavelength buried radials turns the ground underneath from the typically inferior Carolina medium into a superior composite medium. Use of four elevated radials **over that composite medium** is far superior to four elevated over 2-3-4 mS/m. The NEC4.2 analysis linked below does not support the statements in the above quote. This analysis compares two 1/4-wave monopole systems over real earth of conductivity 1 mS/m, d.c. 5 -- which probably is worse than the S. Carolina antenna site under discussion.. One is driven against a set of four 1/4-wave horizontal wires at equal spacing. The horizontal and vertical conductors are all elevated 4.9 meters above the earth. The other is driven against a set of 120 x 1/4-wave radial wires at 3-deg spacing, buried 0.2 meters in the earth. The two NEC models show no geometry or segment errors when run. The peak gains of the two systems in these quickly-written models are within 0.5 dB of each other, and occur at the same elevation angle. Their gains could have been made much closer to each other by trimming the monopole heights a small amount. A peak gain of 5.16 dBi occurred in the horizontal plane for the elevated system over perfect earth, which is exactly as predicted for that system by antenna theory. Probably this illustration is sufficient to prove that elevated radials do not need to be installed over a highly conductive ground plane in order for the performance of the monopole using them to be the ~ equivalent of the same monopole driven against a set of 120 x 1/4-wave buried radials. http://s20.postimg.org/6hfsl64ml/Elevated_vs_Buried_Radials.jpg R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
It would be interesting to see the same modelling over nonconductive rock earth. I suspect once the soil gets bad enough that there is essentially no electron mobility the ground plane (elevated radials) antenna begins to act as if it was in free space - or at least a substantial fraction of a wavelength above the ground - which can reduce ground losses substantially due to the reduction of fields in the soil. While 1 km field readings are interesting, 1 km is only 6 wavelengths at 160 meters (and less in the AM band) so those values still contain a strong near field component and do not adequately reflect the true ground losses. If one wants to really measure ground losses, it takes at least two readings - one at 1 mile (~10 wavelengths) and another at 1.4 miles or 2 miles *along the same radial*. The departure from square law losses can be attributed to additional ground losses. Although 1 and 1.4/2 mi field strength specifically measures groundwave losses, the soil conditions should be homogeneous enough in the skywave launching region that the ground wave case will provide far greater accuracy than any modelling. The problem is that accurate measurement of field strength is difficult - particularly in urban/suburban areas - and nobody wants to take the time to do it unless they are required to do so. Even the AM broadcasters take pains to select monitoring points well away from clutter. 73, ... Joe, W4TV On 1/23/2014 12:05 AM, Mike Waters wrote: A very respected authority on radial systems, Rudy Severns N6LF, has this to say about 4 elevated radials: Since my QST article I've done some modeling to explore the sensitivity of a simple 4-radial system to asymmetries in the radial fan. The modeling easily replicates Weber's results and the news is even worse than Dick thought! The 4-radial system is indeed very sensitive to quite small irregularities and/or nearby conductors. It's easy to demonstrate pattern distortions of 2-3 dB and increased ground losses of 1-2 dB and these are by no means worst cases. More importantly, the modeling shows that as the number of elevated radials is increased the sensitivity goes down quickly. Elevated systems with 10-12 radials are not very sensitive to reasonable asymmetries. It turns out that a number of hams have observed significant improvements in their elevated systems by going to 10 or more radials. Both modeling and experiment seem to agree. I doubt that the average 4-radial system is actually performing as advertized. No doubt there are exceptions but the advice I presently give is to use 10 or more radials whenever possible in an elevated system. (From http://rudys.typepad.com/files/december-2010-letter-to-qst-technical-correspondence.pdf ) See http://www.antennasbyn6lf.com/ 73, Mike www.w0btu.com On Wed, Jan 22, 2014 at 7:18 AM, Richard Fry r...@adams.net wrote: C. Cunningham wrote: If you get up to 4 symmetrical elevated radials there's not much to be gained by adding more. There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Probably this refers to the paper of Clarence Beverage titled NEW AM BROADCAST ANTENNA DESIGNS HAVING FIELD VALIDATED PERFORMANCE. It is available as a PDF download from http://www.commtechrf.com/downloads.asp . Below is a quote from that paper showing that the __measured__ groundwave field at 1 km radiated by a base-insulated, 1/4-wave vertical using four elevated radials was within 0.14 decibels of that from a perfect 1/4-wave vertical monopole driven against 120 x 1/4-wave buried radials. The r-f loss resistance of 120 x 1/4-wave buried radials used in a monopole antenna system typically is less than 2 ohms in the MW and low-HF bands, regardless of the conductivity of the earth in which they are buried. The use of four elevated 1/4-wave radials in this system produced almost identical performance to using a full set of 120 x 1/4-wave buried radials. The first permanent use of an elevated radial ground system appears to be at WPCI, 1490 kHz in Greenville, South Carolina. This installation, designed by William A. Culpepper, involved replacing a standard buried system with a four wire elevated system consisting of #10 solid copper wire, one quarter wave in length, and supported on treated wooden posts which keep the radials 4.9 meters above ground. The antenna radiation efficiency, based on field strength readings on the eight cardinal radials, was 302 mV/m at 1 kilometer versus the predicted FCC value of 307 mV/m. The WPCI installation was unique in that the tower was base insulated but the radials came right up to the tower, 4.9 meters above ground and terminated in insulators. The tower was fed from the tuning unit, through a piece of coax to the 5 meter point on the tower where the center conductor of the coax was attached to the tower
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Thu, Jan 23, 2014 at 10:12 AM, Richard Fry r...@adams.net wrote: Guy Olinger wrote: Careful here ... The presence of 0.4 wavelength buried radials turns the ground underneath from the typically inferior Carolina medium into a superior composite medium. Use of four elevated radials **over that composite medium** is far superior to four elevated over 2-3-4 mS/m. The NEC4.2 analysis linked below does not support the statements in the above quote. It does not. That is a fact. But, again, be careful. It's not because NEC x.x produces the right numbers in all circumstances. NEC x.x has no means of literally calculating ground specifics as if ground were a conductor. Norton Sommerfeld (high accuracy ground) is an **approximation method**. Like any approximation method, it is selected to serve a particular paradigm of circumstances, and will be blind and weak to others. NEC 4.x ground calculation is *tuned* for the *money* paradigm, the commercial MF BC paradigm. It underestimates ground loss where radials would not be accepted as kosher by the FCC. The particular blind spot that applies to extrapolations of commercial BC experience is actual loss in earth, where vertical principal radiators are involved, and sparse and/or irregular and/or short radials/counterpoise are used. The demonstration of this weakness is to spend time trying to get NEC 4.x to predict current carefully MEASURED in radials in the watershed 1937 Brown, Lewis Epstein study, figure 42. NEC x.x can't do it because it is using an **approximation** method for those calculations. You will never generate those dips in the radial current. That requires treating ground as a finite network of small conductors, and running the calculations as if everything was wire, where the ground characteristics defined wire resistance and lossy wire insulation of the stand-in wires. This results in a computational density which is the side of the square divided by the spacing of data points raised to the FOURTH power. Squared because 5 on a side is 25 points overall, 10 on a side is 100 points, 100 on a side is 10,000 points, etc. NEC literal calculations generate a square law number of operations on data points required for a literal calculation. Every data point must be related to every other data point and the results of that calculation book-kept, a book of comparison points. A 100 meter square with data points every meter generates 10,000 data points (one for each unique square meter). This results in 100,000,000 comparison points. A 500 meter square with the same granularity generates 250,000 data points, and 62,500,000,000 comparison points. If each comparison calculation in the 500 meter model took 2 microseconds and occupied 16 bytes of storage, the literal calculations of a 500 meter square would take 125,000 seconds and a terabyte of active processing memory with an working set pretty close to the entirety, making the process highly storage-bound, Accounting for that and using a highly optimistic 10 microsecond storage bound processing time, the run time balloons to 174 hours or a little over a week. So both the storage required and the run time are multiplied by quite worse than a square law, and even with modern fast PC's can generate week and month-long run times. Going back to the time of origin of the Sommerfeld, the state of computation back then meant literal method programs NEVER completed. You did an *approximation* method or you did nothing at all. And that bordering-on-impossible task *assumes* that ground has a *monolithic* quality. This is not at all to minimize the approximation method. Those guys were rightfully heroes for coming up with something that could run to completion at all, and be tunable to attain decently accurate results in the *money* paradigm of commercial MF BC radio. Just don't equate NEC to natural law. There are scattered places where the limitations bung the results, like 160m ham radio and small lots. We have got to get away from this idea that in all the problems presented to NEC that all the issues are being calculated directly from basic radio math equations in EE courses. When NEC x.x can generate the BLE *measured* curves from real ground data, I'll be riveted to the process, God permitting I live so long. 73, Guy K2AV _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Guy Olinger posted: NEC 4.x ground calculation is *tuned* for the *money* paradigm, the commercial MF BC paradigm. It underestimates ground loss where radials would not be accepted as kosher by the FCC. ... Just don't equate NEC to natural law. Some may believe/promote the concept that NEC software is written to favor the commercial MF BC paradigm. But if such is true, those promoters would do well to perform a NEC study supporting their viewpoint, and post a link to that study in this thread. Note that the NEC4.2 analysis I generated and linked at http://s20.postimg.org/6hfsl64ml/Elevated_vs_Buried_Radials.jpg closely replicates the measured results of a real-world monopole system elevated 4.9 meters above the earth. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
The first permanent use of an elevated radial ground system appears to be at WPCI, 1490 kHz in Greenville, South Carolina. This installation, designed by William A. Culpepper, involved replacing a standard buried system with a four wire elevated system consisting of #10 solid copper wire, one quarter wave in length, and supported on treated wooden posts which keep the radials 4.9 meters above ground. The antenna radiation efficiency, based on field strength readings on the eight cardinal radials, was 302 mV/m at 1 kilometer versus the predicted FCC value of 307 mV/m. The WPCI installation was unique in that the tower was base insulated but the radials came right up to the tower, 4.9 meters above ground and terminated in insulators. The tower was fed from the tuning unit, through a piece of coax to the 5 meter point on the tower where the center conductor of the coax was attached to the tower and the shield to the elevated radials. This feed system resulted in a higher feed resistance than would normally be expected. Data on this facility was taken from the FCC files. An intriguing paper. Nice to see something actually based on science and true field measurements. A couple of questions. With the radials being 4.9 meters above ground, do the radials literally come up to the tower and then travel down the leg to connect to the ground side of the insulator or do they travel in close to the tower and angle downward? Does a FS measurement taken at 1 kilometer fully reflect the true angle of radiation and overall performance of the antenna for purposes of distant signals? 73. . . Dave W0FLS _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Wed, Jan 22, 2014 at 8:18 AM, Richard Fry r...@adams.net wrote: The first permanent use of an elevated radial ground system appears to be at WPCI, 1490 kHz in Greenville, South Carolina. This installation, designed by William A. Culpepper, involved replacing a standard buried system with a four wire elevated system consisting of #10 solid copper wire, one quarter wave in length, and supported on treated wooden posts which keep the radials 4.9 meters above ground. Careful here. The buried radials were NOT dug up. Replacing means moving the counterpoise connection of the feed system from the buried system to the elevated system. The presence of 0.4 wavelength buried radials turns the ground underneath from the typically inferior Carolina medium into a superior composite medium. Use of four elevated radials **over that composite medium** is far superior to four elevated over 2-3-4 mS/m. You said: Such characteristics would apply to the use of elevated radial systems by ham radio operators as well as they do for AM broadcast stations. Such a statement requires qualification if the basis of the BC experience includes the previous dense radial field in poor earth **which was not dug up**, and in all likelihood deliberately left in place by the engineer for the now well-known enhancement of sparse elevated radials over poor earths. Why spend a lot of money to dig up the radials? Retire them in place, and harvest the rewards of a far more conductive composite medium underneath the raised radials. I stand by my earlier statements. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Dave W0FLS wrote: With the radials being 4.9 meters above ground, do the radials literally come up to the tower and then travel down the leg to connect to the ground side of the insulator or do they travel in close to the tower and angle downward? From the text of that paper, it appears that the four horizontal radials are attached to the monopole by insulated supports at 4.9-m elevation points above the earth, and terminate there. The coax center conductor is bonded to the tower at that same elevation, and the coax outer conductor attaches to the common point of the four horizontal radials at that elevation. There is no need as far as system radiation efficiency for any of the conductors of this antenna system to have a physical connection to the earth. Probably this system does have conductive paths provided by a static drain choke to a lightning ground buried in the earth (maybe a few ground rods), and an arc gap across the base insulator -- but the paper did not include those details. They would have almost no affect on the radiation efficiency of this system, in any case. Does a FS measurement taken at 1 kilometer fully reflect the true angle of radiation and overall performance of the antenna for purposes of distant signals? The relative field (E/Emax) of the vertical plane field pattern radiated by __all__ monopoles of ~ 1/4-wave in height and less is very close to the cosine of the elevation angle. The cosine of zero degrees is 1 (unity), which means that maximum field is radiated toward the horizon. The cosine of 30 degrees is 0.87, which means that the field at that elevation angle is 87% of the field in the horizontal plane. Etc. Referencing back to Clarence Beverage's data, this means that the field at 1 km radiated by that system toward a 30-deg elevation angle is 0.87 x 302 mV/m = 263 mV/m (approx). The relative values of those fields at an infinite distance over a real-earth ground plane no longer have the relationships they had at 1 km, but that does not alter the fact that those relationships existed at that 1 km distance, in the first place. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
I live on a former AM BC site, and cannot see any way that you could put up 4 elevated radials and disconnect the ground system that was in place. The ground system here is typical installation and it is bonded with 4 inch copper strap to everything and anything in sight. The tuning networks in the antenna huts were built on aluminum panels that are grounded with 4 inch strap to the radial field, all gear in the transmitter building is grounded with 4 inch to the radial field ground. So its virtually impossible to isolate the gear etc from the ground system, installing 4 elevated radials really showed nothing at all unless they dug up the entire radial field and pulled them out. My door and window frames, steel roof and every water pipe are connected to the radial system. When running 50KW you dont enjoy RF burns. My field here has 120 - 300 ft plus and 120 - 60 foot radials, Im sure 4 elevated radials will do very well. 73 Merv K9FD/KH6 Dave W0FLS wrote: With the radials being 4.9 meters above ground, do the radials literally come up to the tower and then travel down the leg to connect to the ground side of the insulator or do they travel in close to the tower and angle downward? From the text of that paper, it appears that the four horizontal radials are attached to the monopole by insulated supports at 4.9-m elevation points above the earth, and terminate there. The coax center conductor is bonded to the tower at that same elevation, and the coax outer conductor attaches to the common point of the four horizontal radials at that elevation. There is no need as far as system radiation efficiency for any of the conductors of this antenna system to have a physical connection to the earth. Probably this system does have conductive paths provided by a static drain choke to a lightning ground buried in the earth (maybe a few ground rods), and an arc gap across the base insulator -- but the paper did not include those details. They would have almost no affect on the radiation efficiency of this system, in any case. Does a FS measurement taken at 1 kilometer fully reflect the true angle of radiation and overall performance of the antenna for purposes of distant signals? The relative field (E/Emax) of the vertical plane field pattern radiated by __all__ monopoles of ~ 1/4-wave in height and less is very close to the cosine of the elevation angle. The cosine of zero degrees is 1 (unity), which means that maximum field is radiated toward the horizon. The cosine of 30 degrees is 0.87, which means that the field at that elevation angle is 87% of the field in the horizontal plane. Etc. Referencing back to Clarence Beverage's data, this means that the field at 1 km radiated by that system toward a 30-deg elevation angle is 0.87 x 302 mV/m = 263 mV/m (approx). The relative values of those fields at an infinite distance over a real-earth ground plane no longer have the relationships they had at 1 km, but that does not alter the fact that those relationships existed at that 1 km distance, in the first place. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Guy Olinger wrote (responding to a quote from me that he included): Such characteristics would apply to the use of elevated radial systems by ham radio operators as well as they do for AM broadcast stations. Such a statement requires qualification if the basis of the BC experience includes the previous dense radial field in poor earth **which was not dug up**, and in all likelihood deliberately left in place by the engineer for the now well-known enhancement of sparse elevated radials over poor earths. Just to note that several installations of new AM broadcast antenna systems using elevated radials have been installed at sites where rocky earth prevented the use of ANY buried radials, and none ever were installed. Even though earth conductivity at / near those sites was very poor, the radiation efficiencies of those antenna systems were very close to those of perfect monopoles over a perfect ground plane. R. Fry _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
No doubt! Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Merv Schweigert Sent: Wednesday, January 22, 2014 2:08 PM To: topband@contesting.com Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? I live on a former AM BC site, and cannot see any way that you could put up 4 elevated radials and disconnect the ground system that was in place. The ground system here is typical installation and it is bonded with 4 inch copper strap to everything and anything in sight. The tuning networks in the antenna huts were built on aluminum panels that are grounded with 4 inch strap to the radial field, all gear in the transmitter building is grounded with 4 inch to the radial field ground. So its virtually impossible to isolate the gear etc from the ground system, installing 4 elevated radials really showed nothing at all unless they dug up the entire radial field and pulled them out. My door and window frames, steel roof and every water pipe are connected to the radial system. When running 50KW you dont enjoy RF burns. My field here has 120 - 300 ft plus and 120 - 60 foot radials, Im sure 4 elevated radials will do very well. 73 Merv K9FD/KH6 Dave W0FLS wrote: With the radials being 4.9 meters above ground, do the radials literally come up to the tower and then travel down the leg to connect to the ground side of the insulator or do they travel in close to the tower and angle downward? From the text of that paper, it appears that the four horizontal radials are attached to the monopole by insulated supports at 4.9-m elevation points above the earth, and terminate there. The coax center conductor is bonded to the tower at that same elevation, and the coax outer conductor attaches to the common point of the four horizontal radials at that elevation. There is no need as far as system radiation efficiency for any of the conductors of this antenna system to have a physical connection to the earth. Probably this system does have conductive paths provided by a static drain choke to a lightning ground buried in the earth (maybe a few ground rods), and an arc gap across the base insulator -- but the paper did not include those details. They would have almost no affect on the radiation efficiency of this system, in any case. Does a FS measurement taken at 1 kilometer fully reflect the true angle of radiation and overall performance of the antenna for purposes of distant signals? The relative field (E/Emax) of the vertical plane field pattern radiated by __all__ monopoles of ~ 1/4-wave in height and less is very close to the cosine of the elevation angle. The cosine of zero degrees is 1 (unity), which means that maximum field is radiated toward the horizon. The cosine of 30 degrees is 0.87, which means that the field at that elevation angle is 87% of the field in the horizontal plane. Etc. Referencing back to Clarence Beverage's data, this means that the field at 1 km radiated by that system toward a 30-deg elevation angle is 0.87 x 302 mV/m = 263 mV/m (approx). The relative values of those fields at an infinite distance over a real-earth ground plane no longer have the relationships they had at 1 km, but that does not alter the fact that those relationships existed at that 1 km distance, in the first place. R. Fry _ 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: Anyone purchased the ARRL book on Short Antennas for160???
A very respected authority on radial systems, Rudy Severns N6LF, has this to say about 4 elevated radials: Since my QST article I've done some modeling to explore the sensitivity of a simple 4-radial system to asymmetries in the radial fan. The modeling easily replicates Weber's results and the news is even worse than Dick thought! The 4-radial system is indeed very sensitive to quite small irregularities and/or nearby conductors. It's easy to demonstrate pattern distortions of 2-3 dB and increased ground losses of 1-2 dB and these are by no means worst cases. More importantly, the modeling shows that as the number of elevated radials is increased the sensitivity goes down quickly. Elevated systems with 10-12 radials are not very sensitive to reasonable asymmetries. It turns out that a number of hams have observed significant improvements in their elevated systems by going to 10 or more radials. Both modeling and experiment seem to agree. I doubt that the average 4-radial system is actually performing as advertized. No doubt there are exceptions but the advice I presently give is to use 10 or more radials whenever possible in an elevated system. (From http://rudys.typepad.com/files/december-2010-letter-to-qst-technical-correspondence.pdf ) See http://www.antennasbyn6lf.com/ 73, Mike www.w0btu.com On Wed, Jan 22, 2014 at 7:18 AM, Richard Fry r...@adams.net wrote: C. Cunningham wrote: If you get up to 4 symmetrical elevated radials there's not much to be gained by adding more. There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Probably this refers to the paper of Clarence Beverage titled NEW AM BROADCAST ANTENNA DESIGNS HAVING FIELD VALIDATED PERFORMANCE. It is available as a PDF download from http://www.commtechrf.com/downloads.asp . Below is a quote from that paper showing that the __measured__ groundwave field at 1 km radiated by a base-insulated, 1/4-wave vertical using four elevated radials was within 0.14 decibels of that from a perfect 1/4-wave vertical monopole driven against 120 x 1/4-wave buried radials. The r-f loss resistance of 120 x 1/4-wave buried radials used in a monopole antenna system typically is less than 2 ohms in the MW and low-HF bands, regardless of the conductivity of the earth in which they are buried. The use of four elevated 1/4-wave radials in this system produced almost identical performance to using a full set of 120 x 1/4-wave buried radials. The first permanent use of an elevated radial ground system appears to be at WPCI, 1490 kHz in Greenville, South Carolina. This installation, designed by William A. Culpepper, involved replacing a standard buried system with a four wire elevated system consisting of #10 solid copper wire, one quarter wave in length, and supported on treated wooden posts which keep the radials 4.9 meters above ground. The antenna radiation efficiency, based on field strength readings on the eight cardinal radials, was 302 mV/m at 1 kilometer versus the predicted FCC value of 307 mV/m. The WPCI installation was unique in that the tower was base insulated but the radials came right up to the tower, 4.9 meters above ground and terminated in insulators. The tower was fed from the tuning unit, through a piece of coax to the 5 meter point on the tower where the center conductor of the coax was attached to the tower and the shield to the elevated radials. This feed system resulted in a higher feed resistance than would normally be expected. Data on this facility was taken from the FCC files. Guy Olinger wrote: Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. A monopole system using ~ four evenly spaced, horizontal, elevated radials or an FCP does not need (or use) a highly-conductive region (FCC spec radials) around the base of the vertical radiator, because in such antenna systems the r-f currents flowing on its vertical and horizontal wires to produce radiation do not travel through the earth. Note that the system described in the quote from Clarence Beverage's paper (above) was installed/tested near Greenville, South Carolina -- a region having earth conductivity of not more than 4 mS/m per the FCC M3 conductivity map, and probably less than that. Yet it produced almost 100% radiation efficiency as measured by a broadcast consulting engineer using a calibrated field intensity meter. Such characteristics would apply to the use of elevated radial systems by ham radio operators as well as they do for AM broadcast stations.
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
However, I did run into an antenna design that was significantly different (to me, anyway) last month, in an old article about inverted-Ls by L.B. Cebik. He showed an inverted-L fed at the transition from vertical to horizontal. Open-wire line ran down and away from it at a 45 degree angle. Basically, it's a dipole with one wire horizontal and the other wire hanging down vertically, so no radials are required. It might be fun to at least model it, if not actually try one on 160 or 80 sometime. The vertical portion would have to be bent and run parallel to the earth in some cases. Anyone here ever try one like it on 160? When the antenna is less than 1/2 wave long, and if we do not change the antenna configuration, we can move the feedline around in an antenna until we turn blue and the only thing that changes is feed impedance. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 7:36 PM, Tom W8JI w...@w8ji.com wrote: ... an inverted-L fed at the transition from vertical to horizontal. Open-wire line ran down and away from it at a 45 degree angle. Basically, it's a dipole with one wire horizontal and the other wire hanging down vertically, so no radials are required. It might be fun to at least model it, if not actually try one on 160 or 80 sometime ... When the antenna is less than 1/2 wave long, and if we do not change the antenna configuration, we can move the feedline around in an antenna until we turn blue and the only thing that changes is feed impedance. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
I've built them for 40 and 80 via his modeling years ago. Fed both up high, and both down low. High feed 'seemed better', but no real way to tell. Worked a RU station on 80 from KL7 so they do emit a signal. It was a good aerial, easy to build, with some vertical component to the pattern. On 160 it may take some bending. Fed low it's a vert with an elevated radial. Two would be better, but then so would four and so on. 73, Gary NL7Y Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Oh, I left out the RU was in Antarctica. 73, Gary NL7Y I've built them for 40 and 80 via his modeling years ago. Fed both up high, and both down low. High feed 'seemed better', but no real way to tell. Worked a RU station on 80 from KL7 so they do emit a signal. It was a good aerial, easy to build, with some vertical component to the pattern. On 160 it may take some bending. Fed low it's a vert with an elevated radial. Two would be better, but then so would four and so on. 73, Gary NL7Y Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Well, you'd have a slant or tilt polarized radiator. You could make the top horizontal wire a 1/4 wavelength and let it be an elevated radial and treat the vertical wire (probably bent horizontal at some lower altitude) as a vertical radiator, but you'd still have a tilt polarized radiator because of the horizontal and vertical high currents at high elevations. Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Tuesday, January 21, 2014 10:13 PM To: Tom W8JI Cc: topband Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 7:36 PM, Tom W8JI w...@w8ji.com wrote: ... an inverted-L fed at the transition from vertical to horizontal. Open-wire line ran down and away from it at a 45 degree angle. Basically, it's a dipole with one wire horizontal and the other wire hanging down vertically, so no radials are required. It might be fun to at least model it, if not actually try one on 160 or 80 sometime ... When the antenna is less than 1/2 wave long, and if we do not change the antenna configuration, we can move the feedline around in an antenna until we turn blue and the only thing that changes is feed impedance. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
That's a good one for 80m from KL7! FB! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Gary and Kathleen Pearse Sent: Tuesday, January 21, 2014 10:22 PM To: topband List Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? Oh, I left out the RU was in Antarctica. 73, Gary NL7Y I've built them for 40 and 80 via his modeling years ago. Fed both up high, and both down low. High feed 'seemed better', but no real way to tell. Worked a RU station on 80 from KL7 so they do emit a signal. It was a good aerial, easy to build, with some vertical component to the pattern. On 160 it may take some bending. Fed low it's a vert with an elevated radial. Two would be better, but then so would four and so on. 73, Gary NL7Y Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
The only real way to tell is have one of each, and do many instant A-B comparisons over a period of time. I just have two 10'+ high elevated radials on my bottom-fed L. It seems to work well, but I should add more radials this summer. And that's what I'll probably do before I ever build one of those. http://www.w0btu.com/160_meters.html#inv-l_antenna 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 9:20 PM, Gary and Kathleen Pearse pea...@gci.netwrote: I've built them for 40 and 80 via his modeling years ago. Fed both up high, and both down low. High feed 'seemed better', but no real way to tell. Worked a RU station on 80 from KL7 so they do emit a signal. It was a good aerial, easy to build, with some vertical component to the pattern. On 160 it may take some bending. Fed low it's a vert with an elevated radial. Two would be better, but then so would four and so on. 73, Gary NL7Y Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Well, I've worked a lot of good stuff all over the world on 160 with an inverted L with two elevated radials - because that's what I had room for. If you get up to 4 symmetrical elevated radials there's not much to be gained by adding more. There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Tuesday, January 21, 2014 10:28 PM To: topband List Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? The only real way to tell is have one of each, and do many instant A-B comparisons over a period of time. I just have two 10'+ high elevated radials on my bottom-fed L. It seems to work well, but I should add more radials this summer. And that's what I'll probably do before I ever build one of those. http://www.w0btu.com/160_meters.html#inv-l_antenna 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 9:20 PM, Gary and Kathleen Pearse pea...@gci.netwrote: I've built them for 40 and 80 via his modeling years ago. Fed both up high, and both down low. High feed 'seemed better', but no real way to tell. Worked a RU station on 80 from KL7 so they do emit a signal. It was a good aerial, easy to build, with some vertical component to the pattern. On 160 it may take some bending. Fed low it's a vert with an elevated radial. Two would be better, but then so would four and so on. 73, Gary NL7Y Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Found paper logs from July 1997…it was VP8CTR on 3796 SSB at our SR, and a Ukranian base not RU. Still, Cebik's L worked. 73, Gary NL7Y That's a good one for 80m from KL7! FB! 73, Charlie, K4OTV Oh, I left out the RU was in Antarctica. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
The real key is symmetrical, according to the stuff I re-read earlier today by Rudy, N6LF and K9YC. Mine aren't symmetrical. The N radial is straight; but the S radial has to zig-zag, because I'm too close the neighbor's pasture fence. The current is almost certainly different on each radial. 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 9:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: Well, I've worked a lot of good stuff all over the world on 160 with an inverted L with two elevated radials - because that's what I had room for. If you get up to 4 symmetrical elevated radials there's not much to be gained by adding more. ... _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On 1/21/2014 5:36 PM, Tom W8JI wrote: When the antenna is less than 1/2 wave long, and if we do not change the antenna configuration, we can move the feedline around in an antenna until we turn blue and the only thing that changes is feed impedance. AND, potentially, moving the feedpoint can change the common mode current on the transmission line, which WILL change more than the feedpoint impedance. This will depend on the line (2-wire or coax), the electrical length of the line, the degree of imbalance in the system, the orientation of the feedline with respect to the antenna, and whether the line is isolated on either or both ends by a choke or transformer. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Tue, Jan 21, 2014 at 10:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. A ham is talking about two or four raised over plain dirt. Two or four over ugly North Carolina 2 millisiemen will be down, though one will need comparison RBN plots watching an entire 160 contest to see it. It's not so far down though that you won't work happy DX with it, but there is a power loss. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
On Tue, Jan 21, 2014 at 10:12 PM, Mike Waters mikew...@gmail.com wrote: Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? Yeah, but this is 160, and if you can get the bend up 75 feet or so you are feeding a half-size doublet that consists only of a pair of 1/8 waves. Really a very different antenna story on 80 meters where the same 75 feet can get your vertical and horizontal to a 1/4 wave each. On 160 with a split 1/4 wave L you get a feedpoint at the bend of Z = 12 - j1100 ohms over average ground. To tune out all that capacitive reactance will employ ~ 94 uH coil or its various equivalents with transformers, feedline tricks, etc, making the match quite narrow, along with many opportunities to generate loss if the whole thing isn't done tightly according to the book. Without any loss factors and with a perfect tuning inductor the 2:1 bandwidth at 12 ohms at feedpoint is only about 10 kHz. Unmatched 50 ohm SWR is over 4:1. Current at feedpoint is over 11 amps for 1500 watts, meaning any balun device must be designed for the heavy current ** at 160m **. Also meaning that a lot of the balun stuff I've seen will burn and/or leave huge amounts of common mode on the feedline. If you use balanced line, the typical 450 window line will have an impedance of 13k a quarter wave away. All this would be why such a 160m configuration is really not a big hit and not common as nails. 73, Guy _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. ON4UN's original 80 meter wire 4-square hug around his 160 meter tower came close to that description. The 4 square had a single elevated radial for each 80 meter element but they were all over some 100+ radials for 160 meters - most at least 1/4 wave long. 73, ... Joe, W4TV On 1/21/2014 11:32 PM, Guy Olinger K2AV wrote: On Tue, Jan 21, 2014 at 10:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. A ham is talking about two or four raised over plain dirt. Two or four over ugly North Carolina 2 millisiemen will be down, though one will need comparison RBN plots watching an entire 160 contest to see it. It's not so far down though that you won't work happy DX with it, but there is a power loss. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Thanks, Guy. If I ever try this, it will very likely be on 80m first, and each half will be 1/4 wave. 73, Mike www.w0btu.com On Tue, Jan 21, 2014 at 10:39 PM, Guy Olinger K2AV olin...@bellsouth.netwrote: Wouldn't feeding it up high in the corner like that at least eliminate the need for radials? Yeah, but this is 160, and if you can get the bend up 75 feet or so you are feeding a half-size doublet that consists only of a pair of 1/8 waves. Really a very different antenna story on 80 meters where the same 75 feet can get your vertical and horizontal to a 1/4 wave each. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???
Oh, OK. That should have worked. And note who you're talking about. :) But have you heard of a ham that had 120 1/4 wave bare buried around his 130' insulated tower, and then switched to two raised radials with the 120 left in place. Commercial BC is in the fix of having to maintain the field strength, even when the radials start to get even mildly inefficient. They would be all over having to raise power to compensate. I doubt a typical ham would even know anything was going wrong at the loss level that would instigate action at a BC installation. 73, Guy On Tue, Jan 21, 2014 at 11:42 PM, Joe Subich, W4TV li...@subich.com wrote: I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. ON4UN's original 80 meter wire 4-square hug around his 160 meter tower came close to that description. The 4 square had a single elevated radial for each 80 meter element but they were all over some 100+ radials for 160 meters - most at least 1/4 wave long. 73, ... Joe, W4TV On 1/21/2014 11:32 PM, Guy Olinger K2AV wrote: On Tue, Jan 21, 2014 at 10:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. A ham is talking about two or four raised over plain dirt. Two or four over ugly North Carolina 2 millisiemen will be down, though one will need comparison RBN plots watching an entire 160 contest to see it. It's not so far down though that you won't work happy DX with it, but there is a power loss. 73, Guy. _ 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: Anyone purchased the ARRL book on Short Antennas for160???
That's certainly true! Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Guy Olinger K2AV Sent: Tuesday, January 21, 2014 11:59 PM To: Joe Subich, W4TV Cc: TopBand List Subject: Re: Topband: Anyone purchased the ARRL book on Short Antennas for160??? Oh, OK. That should have worked. And note who you're talking about. :) But have you heard of a ham that had 120 1/4 wave bare buried around his 130' insulated tower, and then switched to two raised radials with the 120 left in place. Commercial BC is in the fix of having to maintain the field strength, even when the radials start to get even mildly inefficient. They would be all over having to raise power to compensate. I doubt a typical ham would even know anything was going wrong at the loss level that would instigate action at a BC installation. 73, Guy On Tue, Jan 21, 2014 at 11:42 PM, Joe Subich, W4TV li...@subich.com wrote: I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. ON4UN's original 80 meter wire 4-square hug around his 160 meter tower came close to that description. The 4 square had a single elevated radial for each 80 meter element but they were all over some 100+ radials for 160 meters - most at least 1/4 wave long. 73, ... Joe, W4TV On 1/21/2014 11:32 PM, Guy Olinger K2AV wrote: On Tue, Jan 21, 2014 at 10:40 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: There's been a lot of work done in the broadcast industry using elevated radials to replace deteriorated buried radial fields that shows that pretty clearly. It was published in some IEEE transactions some years ago. Be careful not to extrapolate very specifically qualified broadcast experience into ham radio. Originally FCC spec radials still make the close foreground earth appear VERY conductive, which is NOT an advantage one will have putting up two or four radials over plain old dirt, unless one is talking about midwest USA 30 millisiemen super dirt. I have yet to hear about a ham who had 120 buried bare radials underneath his two raised radials. A ham is talking about two or four raised over plain dirt. Two or four over ugly North Carolina 2 millisiemen will be down, though one will need comparison RBN plots watching an entire 160 contest to see it. It's not so far down though that you won't work happy DX with it, but there is a power loss. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
