|
On Tue, 21 Jun 2005 17:35:11 -0400, "Walter Maxwell"
wrote: Your mentioning Mathcad, (I have 2000i ed.) Hi Walt, My version is ancient in comparison, but I can't see the cost of upgrading. made me think of using Excel to produce some graphs of the data, however, there are two other projects that must come first. I have used Mathcad only to solve problems using the equations one can build there, and have not explored the graphing possibilities. I enjoy Mathcad for tying them together. When I think of Excel, it is with pedestrian bar graphs and pie charts. With both Excel and Mathcad available do you think I should spend the time learning graphics with Mathcad, or stick with Excel which I already know how to use? Stick with Excel, but look into XLZIZL.xls for analysis. 73's Richard Clark, KB7QHC |
"Richard Clark" wrote in message ... On Tue, 21 Jun 2005 17:35:11 -0400, "Walter Maxwell" wrote: Your mentioning Mathcad, (I have 2000i ed.) Hi Walt, My version is ancient in comparison, but I can't see the cost of upgrading. made me think of using Excel to produce some graphs of the data, however, there are two other projects that must come first. I have used Mathcad only to solve problems using the equations one can build there, and have not explored the graphing possibilities. I enjoy Mathcad for tying them together. When I think of Excel, it is with pedestrian bar graphs and pie charts. With both Excel and Mathcad available do you think I should spend the time learning graphics with Mathcad, or stick with Excel which I already know how to use? Stick with Excel, but look into XLZIZL.xls for analysis. 73's Richard Clark, KB7QHC Thanks for the advice, Richard, Walt |
On Tue, 21 Jun 2005 23:42:45 +0000 (UTC), "Reg Edwards"
wrote: Least of all does KB7QHC's lying slander worry me. I love you too, Reg. Thanx for taking the time to acknowledge me. 73's Richard Clark, KB7QHC |
Reg Edwards wrote: Walt, would it be possible for somebody to go to B.L & E's original site and measure the soil charateristics which they completely forgot all about. . . But what would that tell us about the soil conditions to, say, three skin depths -- or even one? What conclusions could we draw from that information? Roy Lewallen, W7EL ==================================== None, except that you are nit-picking as usual. And that B, L & E, all three of them, were floundering about in an amateurish fashion. Yet it had been well known to others for 35 years that soil conductivity and permittivity had a profound effect on ground wave propagation. All they had demonstrated was that 113 radials was more than sufficient for MF and low HF broadcast propagation which was what everybody already knew. And so the rounded-up, Marzipan the Magician, magic number of 120 got stuck in the bibles. A typical American way of going about things. ;o) ---- Reg. |
"Richard Clark" wrote in message ... On Tue, 21 Jun 2005 23:42:45 +0000 (UTC), "Reg Edwards" wrote: Least of all does KB7QHC's lying slander worry me. I love you too, Reg. Thanx for taking the time to acknowledge me. 73's Richard Clark, KB7QHC Lying slander is a redundancy, isn't it? Just the opposite of sanitary sewer as an oxymoron. I've been enjoying Richard's redundancy and Punchinello's responses immensely. Walt, W2DU |
Reg Edwards wrote:
[Responding to the question of what useful information could be obtained from measuring the surface soil conductivity at the B, L, and E site] None But I'm sure that won't stop you from your frequent complaints that they "forgot" to measure it. I see you've found other things to criticize, though. . . , except that you are nit-picking as usual. Asking what use it would be to measure the surface conductivity (as you suggested) is nit-picking? You have a strange way of evaluating things. And that B, L & E, all three of them, were floundering about in an amateurish fashion. Ah, you play the role of armchair quarterback very well. Sure is too bad you didn't think of doing the experiment in 1937 -- I'm sure you would have done it right. All AM broadcast stations would be using precisely 100, not 120 radials, and we'd know the surface ground conductivity of the measurement field (but still wouldn't know what to do with the information). The Reg of '05 would have the warm, satisfied feeling of knowing that another seminal piece of work was done by one of Her Magisty's loyal subjects (or was it His Magisty in '37 -- I forget) instead of the gnawing aggravation he experiences thinking that some American ruffians might actually have done something useful. Life would sure be a lot better today, wouldn't it? Yet it had been well known to others for 35 years that soil conductivity and permittivity had a profound effect on ground wave propagation. Propagation, yes. But nobody had a good handle of the effect of ground systems on antenna efficiency until their experiments. All they had demonstrated was that 113 radials was more than sufficient for MF and low HF broadcast propagation which was what everybody already knew. You obviously haven't read the paper. It has nothing at all to do with propagation. And so the rounded-up, Marzipan the Magician, magic number of 120 got stuck in the bibles. A typical American way of going about things. ;o) ---- Boy, it really must hurt deeply to think that some Americans did something that the rest of the world considers to be pioneering. Have some more wine -- it'll dull the pain. But under no circumstances should you actually stoop to reading the paper you're so fond of criticizing. It would just make you feel worse. Reg. Roy Lewallen, W7EL certified Reg's Old Wife -- and inveterate nit-picker |
On Tue, 21 Jun 2005 21:34:32 -0400, "Walter Maxwell"
wrote: Lying slander is a redundancy, isn't it? Hi Walt, The laws, and I imagine the understanding, varies immensely across all borders and jurisdictions. In some places it is slander to reveal the truth, in others to disparage with a lie. One could imagine the paradox of uttering a lying truth, I suppose. However, given Reg's propensity to slander outrageously, as though it were a prerogative of old age and infirmity, and to wrap me in under the same mantle well before my time (but perhaps not infirmity); this callow youth takes it as no less honour than the tap of the sword on the shoulders by a Queen. Alternately, lacking any quantitative data, a shortfall that Sir Kelvinator of ice box fame would shudder at, I cannot think Reg's opprobrium is any less part of the act of Punchinello (in other words, indistinguishable from honest labor when such is so mixed with intemperance and reckless fulmination). Either way, I always enjoy the flourish of his hyperbolic arcs. 73's Richard Clark, KB7QHC |
Reg;
How many radials are required in GB for a commercial broadcast station ? "Reg Edwards" wrote in message ... Reg Edwards wrote: ==================================== None, except that you are nit-picking as usual. And that B, L & E, all three of them, were floundering about in an amateurish fashion. Yet it had been well known to others for 35 years that soil conductivity and permittivity had a profound effect on ground wave propagation. All they had demonstrated was that 113 radials was more than sufficient for MF and low HF broadcast propagation which was what everybody already knew. And so the rounded-up, Marzipan the Magician, magic number of 120 got stuck in the bibles. A typical American way of going about things. ;o) ---- Reg. |
"Richard Clark" wrote in message ... On Tue, 21 Jun 2005 21:34:32 -0400, "Walter Maxwell" wrote: Lying slander is a redundancy, isn't it? Hi Walt, The laws, and I imagine the understanding, varies immensely across all borders and jurisdictions. In some places it is slander to reveal the truth, in others to disparage with a lie. One could imagine the paradox of uttering a lying truth, I suppose. However, given Reg's propensity to slander outrageously, as though it were a prerogative of old age and infirmity, and to wrap me in under the same mantle well before my time (but perhaps not infirmity); this callow youth takes it as no less honour than the tap of the sword on the shoulders by a Queen. Alternately, lacking any quantitative data, a shortfall that Sir Kelvinator of ice box fame would shudder at, I cannot think Reg's opprobrium is any less part of the act of Punchinello (in other words, indistinguishable from honest labor when such is so mixed with intemperance and reckless fulmination). Either way, I always enjoy the flourish of his hyperbolic arcs. 73's Richard Clark, KB7QHC Richard, as I both said and implied earlier, I enjoy you both immensely. Your elegant usage of expression as a degreed literary is hardly unnoticeable. Walt |
Walter:
Does that mean you do agree with me and Shakespeare sucks--or not? grin John "Walter Maxwell" wrote in message ... "Richard Clark" wrote in message ... On Tue, 21 Jun 2005 21:34:32 -0400, "Walter Maxwell" wrote: Lying slander is a redundancy, isn't it? Hi Walt, The laws, and I imagine the understanding, varies immensely across all borders and jurisdictions. In some places it is slander to reveal the truth, in others to disparage with a lie. One could imagine the paradox of uttering a lying truth, I suppose. However, given Reg's propensity to slander outrageously, as though it were a prerogative of old age and infirmity, and to wrap me in under the same mantle well before my time (but perhaps not infirmity); this callow youth takes it as no less honour than the tap of the sword on the shoulders by a Queen. Alternately, lacking any quantitative data, a shortfall that Sir Kelvinator of ice box fame would shudder at, I cannot think Reg's opprobrium is any less part of the act of Punchinello (in other words, indistinguishable from honest labor when such is so mixed with intemperance and reckless fulmination). Either way, I always enjoy the flourish of his hyperbolic arcs. 73's Richard Clark, KB7QHC Richard, as I both said and implied earlier, I enjoy you both immensely. Your elegant usage of expression as a degreed literary is hardly unnoticeable. Walt |
Not to be confused with the company bearing the name (Shakespeare) and
having made, or is making, chicken band antennas... John "John Smith" wrote in message ... Walter: Does that mean you do agree with me and Shakespeare sucks--or not? grin John "Walter Maxwell" wrote in message ... "Richard Clark" wrote in message ... On Tue, 21 Jun 2005 21:34:32 -0400, "Walter Maxwell" wrote: Lying slander is a redundancy, isn't it? Hi Walt, The laws, and I imagine the understanding, varies immensely across all borders and jurisdictions. In some places it is slander to reveal the truth, in others to disparage with a lie. One could imagine the paradox of uttering a lying truth, I suppose. However, given Reg's propensity to slander outrageously, as though it were a prerogative of old age and infirmity, and to wrap me in under the same mantle well before my time (but perhaps not infirmity); this callow youth takes it as no less honour than the tap of the sword on the shoulders by a Queen. Alternately, lacking any quantitative data, a shortfall that Sir Kelvinator of ice box fame would shudder at, I cannot think Reg's opprobrium is any less part of the act of Punchinello (in other words, indistinguishable from honest labor when such is so mixed with intemperance and reckless fulmination). Either way, I always enjoy the flourish of his hyperbolic arcs. 73's Richard Clark, KB7QHC Richard, as I both said and implied earlier, I enjoy you both immensely. Your elegant usage of expression as a degreed literary is hardly unnoticeable. Walt |
Roy, W7EL wrote:
"What conclusions could we draw from that information?" My comment is a little off topic as it is not about measuring soil constants. It is only an opinion that the FCC`s decisions regarding a standard grounding system for medium wave broadcast stations worked out very well. 120 redials each about 1/4-wavelength seems to work well whether soil is good or bad. In summer or winter, if the ground cracks open from drought or is covered with a foot or more of floodwater, the tower currents and field strengths hardly change at all. Directional patterns are unaffected. Amazing and well done! Best regards, Richard Harrison, KB5WZI |
"Fred W4JLE" wrote Reg; How many radials are required in GB for a commercial broadcast station ? ==================================== Fred, Depends on how long and thick they are. But in general, just sufficient to meet overall technical and economic requirements with one or two more for luck. Design engineers, just to be awkward, are inclined to deliberately avoid 120. Then they can sit back and have a good laugh when it still works. ---- Reg, G4FGQ |
I forgot to say all measurements were made in or near the domestic
kitchen sink. ---- Reg. |
Reg, G4FGQ wrote:
"A typical American way of going apoutthings.:o) " Later to be called "Shock and Awe"? Best regards, Richard Harrison, KB5WZI |
Earlier I said a volume of soil between electrodes behaves as a
capacitor in parallel with a resistance. To conform better to the impedance-frequency response of real soil, a better simulation is obtained with another resistor in series with the capacitor. Better still add a 3rd resistor in series with a second capacitor, both in shunt with R1, C1 and R2. I have a computer program somewhere which assists in designing a circuit to simulate a given type of soil. But what use such circuits might have is a matter for conjecture. It is more convenient and practical to work in terms of resistance rather than the scientific term conductivity. Ohm-metres rather than milli-Siemens. When thinking in terms of conductivity I always feel I should be standing on my head. The resistance measured between opposite faces of a 1-metre cube of the soil is 1000 ohms when the soil has a resistivity of 1000 ohm-meters. A poor soil is 1000 ohms = 1 milli-S Sea water is 0.22 ohms. One can visualise a 1 metre cube of the material. The permittivity of the material being the nunber of times the measured capacitance exceeds the calculated capacitance between the electrodes when only air is present. It's about 9 pF. ---- Reg, G4FGQ |
Roy Lewallen wrote:
But under no circumstances should you actually stoop to reading the paper you're so fond of criticizing. Are BLE's original papers available on the web? If not, that does represent a substantial problem. Despite having several derivative references, I must admit to never having seen the originals either. But I do have enough information to judge BLE's work worthy of respect. Pioneers always deserve an extra helping of respect because - unlike everyone else, including all their critics - they didn't have the benefit of perfect hindsight. On the other hand, that work was done almost three-quarters of a century ago. If we don't know more than the pioneers did, then we have wasted their efforts. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Richard Harrison wrote:
Roy, W7EL wrote: "What conclusions could we draw from that information?" My comment is a little off topic as it is not about measuring soil constants. It is only an opinion that the FCC`s decisions regarding a standard grounding system for medium wave broadcast stations worked out very well. 120 redials each about 1/4-wavelength seems to work well whether soil is good or bad. In summer or winter, if the ground cracks open from drought or is covered with a foot or more of floodwater, the tower currents and field strengths hardly change at all. Directional patterns are unaffected. Amazing and well done! Well, not exactly amazing, since the FCC deliberately requires the ground to be covered by so many radials that the location and its ground conditions don't matter any more. That was an administrative policy decision rather than a technical one. From the technical viewpoint, everybody agrees that 120*0.25wl is more than enough to override the local ground conditions under the tower irrelevant. The real technical question is: how many, and how long, will be "just enough" for "here"? That obviously requires a lot more knowledge and engineering judgement. Having just taken delivery of two miles of radial wire, the question of "How much is enough?" is starting to become very practical... -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Ian White GM3SEK wrote:
. . . The real technical question is: how many, and how long, will be "just enough" for "here"? That obviously requires a lot more knowledge and engineering judgement. . . . And for the purpose at hand. We have to keep in mind that the requirements for AM broadcasters are quite different from those of amateurs. A few percent difference in field strength means a few percent difference in a broadcaster's audience size and therefore in advertising income. This income difference is felt year after year, so any change that brings a few percent increase in field strength is worth a fair amount of money for a broadcaster to implement. On the other hand, a difference of 1 dB (more than a 20% change in efficiency or 10% change in field strength) is seldom worthwhile at all for most amateurs. I'm not sure why the great hangup on how many radials AM broadcasters use. It certainly isn't what most amateurs need. Roy Lewallen, W7EL |
"Roy Lewallen" wrote in message ... Ian White GM3SEK wrote: . . . The real technical question is: how many, and how long, will be "just enough" for "here"? That obviously requires a lot more knowledge and engineering judgement. . . . Well, Ian, the BLE paper reports data allowing one to make that engineering judgement. It's unfortunate that my copy of the paper is in my library in Florida, and I won't be back there until November to scan it for the group. However, I have ordered a copy from the Michigan State U library. The BLE experiments were conducted to determine what combination of radials would form the best simulation of a perfect ground, i.e., what combination would achieve a field strength closest to the ideal calculated value. One factor they considered is that when the spacing between adjacent wires in a grid structure is 1/20 lambda or less, the effect is that of a continuous reflecting surface. The spacing between radials is not exactly the same as a grid structure, but the effect is similar. BLE found that the optimum length of the radials in the ground is not related to resonant length as it is with elevated radials. They found that the principal reason for the optimum length concerns the volume containing the significant energy in the electromagnetic fields in the space surrounding the radiator that intersects the ground. They found that at a distance of 0.4 lambda from the radiator the energy in the fields has reduced to the level of diminishing returns, where collecting the currents at a greater distance would yield no significant decrease in loss resistance, and therefore no further increase in field strength. Indeed, the field strength obtained with at least 90 radials 0.4 lambda in length was found to be insignificantly less than that of a perfect ground. This fact was unknown prior to BLE's experiments. I can't remember the exact difference shown in the graph, but it is inconsequential. With the radials simulating a near-perfect reflecting ground plane the skin depth of the earth beneath the radials is of no consequence, because the RF energy is nearly totally reflected, with only an insignificant amount transmitted through the ground plane. Consequently, the soil conditions directly beneath the ground plane are irrevelant. However, the soil conditions immediately external to the ground plane are important to the intensity of the ground wave propagation from vertical radiators. The poorer the soil conductivity the greater the loss at low angles of elevation. And as we all know, propagation of the ground wave is frequency sensitive. Many years ago, using the FCC propagation charts of field strength vs distance for a conductivity of 8, the geographical area covered with a field strenght of 1 mv/meter at 1 mile for a 250 watt station at 550 KHz would require 47 kilowatts at 1500 KHz to cover the same area with the same signal level. When I receive the requested copy of the BLE paper I'll scan it and publish it for all to see. Walt, W2DU |
"Walter Maxwell" wrote in message ... "Roy Lewallen" wrote in message ... Ian White GM3SEK wrote: . . . The real technical question is: how many, and how long, will be "just enough" for "here"? That obviously requires a lot more knowledge and engineering judgement. . . . Well, Ian, the BLE paper reports data allowing one to make that engineering judgement. It's unfortunate that my copy of the paper is in my library in Florida, and I won't be back there until November to scan it for the group. However, I have ordered a copy from the Michigan State U library. The BLE experiments were conducted to determine what combination of radials would form the best simulation of a perfect ground, i.e., what combination would achieve a field strength closest to the ideal calculated value. One factor they considered is that when the spacing between adjacent wires in a grid structure is 1/20 lambda or less, the effect is that of a continuous reflecting surface. The spacing between radials is not exactly the same as a grid structure, but the effect is similar. BLE found that the optimum length of the radials in the ground is not related to resonant length as it is with elevated radials. They found that the principal reason for the optimum length concerns the volume containing the significant energy in the electromagnetic fields in the space surrounding the radiator that intersects the ground. They found that at a distance of 0.4 lambda from the radiator the energy in the fields has reduced to the level of diminishing returns, where collecting the currents at a greater distance would yield no significant decrease in loss resistance, and therefore no further increase in field strength. Indeed, the field strength obtained with at least 90 radials 0.4 lambda in length was found to be insignificantly less than that of a perfect ground. This fact was unknown prior to BLE's experiments. I can't remember the exact difference shown in the graph, but it is inconsequential. With the radials simulating a near-perfect reflecting ground plane the skin depth of the earth beneath the radials is of no consequence, because the RF energy is nearly totally reflected, with only an insignificant amount transmitted through the ground plane. Consequently, the soil conditions directly beneath the ground plane are irrevelant. However, the soil conditions immediately external to the ground plane are important to the intensity of the ground wave propagation from vertical radiators. The poorer the soil conductivity the greater the loss at low angles of elevation. And as we all know, propagation of the ground wave is frequency sensitive. Many years ago, using the FCC propagation charts of field strength vs distance for a conductivity of 8, the geographical area covered with a field strenght of 1 mv/meter at 1 mile for a 250 watt station at 550 KHz would require 47 kilowatts at 1500 KHz to cover the same area with the same signal level. When I receive the requested copy of the BLE paper I'll scan it and publish it for all to see. Walt, W2DU In my previous post above I forgot to mention that the displacement currents that enter the ground between the radials don't follow the lossy ground to the center of the radial system. Instead, they quickly diffract to the nearest radial and thus continue toward the center along the radial wire. Consequently, the more radials the shorter distance the diffracted current has to travel to reach the higher conductivity of the wire. The last I knew the FCC requires only 90 radials (every 4°) to comply with the regulations, but many BC antenna engineers use 120 (every 3°). I discussed this issue in Chapter 5 in both the 1st and 2nd editions of Reflections, with a diagram of the diffraction phenomenon in Fig. 1. Walt, W2DU |
On Tue, 21 Jun 2005 17:35:11 -0400, "Walter Maxwell"
wrote: "Richard Clark" wrote in message .. . On Mon, 20 Jun 2005 23:17:40 -0400, "Walter Maxwell" wrote: Hi All, Reg asked if I could send my data as an email, so I converted the file to text format to be able to present the data in full here in this msg. I checked to see that the tabular format remained intact, and it did in Outlook Express, so here it is. I hope the tabular format will remain intact in your browsers. Be sure to give your screen maximum width. If it doesn't, let me know and I'll resend in PDF format. I'd like to hear your comments. Hi Walt, Thanx big time for this work of dedication. I have other projects to attend to, but I am sure looking forward to close examination of this trove of data by hunkering down with Mathcad and casting up some charts. Hope to do that within the week if not sooner. 73's Richard Clark, KB7QHC Hi Richard, Your mentioning Mathcad, (I have 2000i ed.) made me think of using Excel to produce some graphs of the data, however, there are two other projects that must come first. I have used Mathcad only to solve problems using the equations one can build there, and have not explored the graphing possibilities. With both Excel and Mathcad available do you think I should spend the time learning graphics with Mathcad, or stick with Excel which I already know how to use? Walt Walt, I'm not Richard but my two cents would be stick with Excel. I have a (now old) version of Mathcad (6.0) and don't use it much. It is much better in handling complex numbers than Excel is tho. Excel does the math just fine, but the clunky text results are a pain. Also, I cannot recommend too highly Dan's (AC6LA) Excel based programs. His MultiNEC front end for NEC, EZNEC, 4nec2, Antenna Model, etc. is used all of the time here. For transmission line stuff, including "building" matching networks XLZIZL is also constantly in use at this QTH. Likewise his stand alone TLDetails.exe should be in every ham's tool kit. (I'm a beginning amateur woodworker and just like woodworkers, hams can never have too many tools.) |
Walter Maxwell wrote:
. . . When I receive the requested copy of the BLE paper I'll scan it and publish it for all to see. Is the publishing of copyrighted papers on the Web generally permitted under fair use rules? The IEEE and other publishers of professional papers charge around $25 for downloaded reprints, and I'd think that would cut into their income. Or does the IEEE specifically permit publishing of their papers on the Web? Roy Lewallen, W7EL |
Walter Maxwell wrote:
In my previous post above I forgot to mention that the displacement currents that enter the ground between the radials don't follow the lossy ground to the center of the radial system. Instead, they quickly diffract to the nearest radial and thus continue toward the center along the radial wire. Consequently, the more radials the shorter distance the diffracted current has to travel to reach the higher conductivity of the wire. The last I knew the FCC requires only 90 radials (every 4°) to comply with the regulations, but many BC antenna engineers use 120 (every 3°). I discussed this issue in Chapter 5 in both the 1st and 2nd editions of Reflections, with a diagram of the diffraction phenomenon in Fig. 1. This interaction among radials has quite a dramatic effect on the effective ground conductivity. I noticed and reported quite some time ago that Reg's ground radial program produced answers which disagree strongly with both BLE and NEC-4 modeling (which agree with each other reasonably well), and speculated that he didn't account for this interaction in his program. (I haven't checked since to see if the program has been modified.) All he says about having to trust the writer of the program if you don't have access to the source code is true. Roy Lewallen, W7EL |
On Tue, 21 Jun 2005 11:37:57 -0400, "Walter Maxwell"
wrote: [snip] Walt, Your's was a particularly heroic effort and I commend you for it. I have taken the data you supplied in text form, converted it to comma separated values (csv) and imported it into XLZIZL where I can use your measured input values, add the two different transmission lines that you used and compute the load resistance at the antenna. I know that you supplied these results, but I find slightly different answers and I believe the reason is as follows: I'm guessing that you calibrated your two lines as one. If I'm wrong, slap me upside the head. Depending on the exact type, RG58(x) has slightly different Zo values. RG141 is specified as 50.0. Your Zo of 54 and your phase constant suggest a Vp of slightly less than .66, which is remarkably close to specification, but slightly low, considering the ~5% (2', RG141) of your composite line has Vp ~ 0.7. This is really getting fussy, but I'm beginning to believe that to possibly make a determination about ground characteristics based on antenna Z measurements, the measurements are going to have to be very precise. |
On Wed, 22 Jun 2005 08:57:00 -0700, Roy Lewallen
wrote: Walter Maxwell wrote: . . . When I receive the requested copy of the BLE paper I'll scan it and publish it for all to see. Is the publishing of copyrighted papers on the Web generally permitted under fair use rules? The IEEE and other publishers of professional papers charge around $25 for downloaded reprints, and I'd think that would cut into their income. Or does the IEEE specifically permit publishing of their papers on the Web? Unless I'm mistaken, the copyright would have had to been renewed to remain in effect. According to this link: http://www.scils.rutgers.edu/~lesk/copyrenew.html it was not. |
On Wed, 22 Jun 2005 09:33:33 -0700, Wes Stewart
wrote: According to this link: http://www.scils.rutgers.edu/~lesk/copyrenew.html it was not. Hi Wes, You should take care to observe the proviso offered: "This file does not contain listings for music, movies, or periodicals." The practice of many journals is that your material, offered for publication, is accepted only with the explicit rights of ownership being transferred to that society. In fact, if you were to cite your own work without giving a reference to that society's publication, then you could be held accountable for plagiarism. The "Open Source" movement has sparked a debate in this regard and academic authors are being better versed on methods that allow them to both publish and retain rights. 73's Richard Clark, KB7QHC |
Wes Stewart wrote:
Unless I'm mistaken, the copyright would have had to been renewed to remain in effect. According to this link: http://www.scils.rutgers.edu/~lesk/copyrenew.html it was not. Thanks for the URL - it looks like it'll come in handy. Unfortunately, the fourth sentence on that page is "This file does not contain listings for music, movies, or periodicals." The BLE paper was published in the _Proceedings of the IRE_, a periodical. Roy Lewallen, W7EL |
"Roy Lewallen" wrote in message ... Walter Maxwell wrote: . . . When I receive the requested copy of the BLE paper I'll scan it and publish it for all to see. Is the publishing of copyrighted papers on the Web generally permitted under fair use rules? The IEEE and other publishers of professional papers charge around $25 for downloaded reprints, and I'd think that would cut into their income. Or does the IEEE specifically permit publishing of their papers on the Web? Roy Lewallen, W7EL Hasn't the copyright expired on material published in 1937? Walt |
On Wed, 22 Jun 2005 13:49:11 -0400, "Walter Maxwell"
wrote: Hasn't the copyright expired on material published in 1937? Hi Walt, You cannot imagine how difficult it is to track down rights' holders. The presumption does not lie in copyright having expired automatically. Many organizations hire lawyers for no other purpose than this paper chase. The author's name is becoming increasingly irrelevant in this age of information. 73's Richard Clark, KB7QHC |
"Walter Maxwell" wrote Reg asked if I could send my data as an email, so I converted the file to text format to be able to present the data in full here in this msg. I checked to see that the tabular format remained intact, and it did in Outlook Express, so here it is. I hope the tabular format will remain intact in your browsers. Be sure to give your screen maximum width. If it doesn't, let me know and I'll resend in PDF format. Walt, W2DU Dipole Terminal Impedance Data Obtained From Measurements at Various Heights Above Ground in the Frequency Range from 14.0 to 15.0 MHz. Measurements Made be W2DU at the W2DU site in DeLand, Florida. ============================================ Data received as an extension to this message. Fills screen very nicely. Thank you very much Walter for your trouble. ---- Reg, G4FGQ =========================================== |
"Wes Stewart" wrote in message ... On Tue, 21 Jun 2005 11:37:57 -0400, "Walter Maxwell" wrote: [snip] Walt, Your's was a particularly heroic effort and I commend you for it. I have taken the data you supplied in text form, converted it to comma separated values (csv) and imported it into XLZIZL where I can use your measured input values, add the two different transmission lines that you used and compute the load resistance at the antenna. I know that you supplied these results, but I find slightly different answers and I believe the reason is as follows: I'm guessing that you calibrated your two lines as one. If I'm wrong, slap me upside the head. Depending on the exact type, RG58(x) has slightly different Zo values. RG141 is specified as 50.0. Your Zo of 54 and your phase constant suggest a Vp of slightly less than .66, which is remarkably close to specification, but slightly low, considering the ~5% (2', RG141) of your composite line has Vp ~ 0.7. This is really getting fussy, but I'm beginning to believe that to possibly make a determination about ground characteristics based on antenna Z measurements, the measurements are going to have to be very precise. Wes You're right, Wes, I calibrated the composite line as one line. And I agree that if you calibrate them separately a small difference in the results will be obtained. But I believe the difference will be insignificant. Consider this: The nominal Zo of RG58 is 55 ohms and that of RG141 is 50, as you point out. The measured Zo of the composite line is 54 ohms. Now also consider this: The nominal vf for RG58 is 0.659 and for RG141 is 0.695. Thus the difference in the nominal Zo is 10% and the difference in vf is 5.5%, but the length of the short portion is only 5% of the total length. From these small differences I presumed the error would be significant. You didn't say exactly how much difference you found, or the procedure you used to determine it. So I made the following calculations from the data where the height is 10 ft at 14.55 MHz: First transforming the measured input impedance through the 40 ft of RG58, and then transforming the impedance found at the load end of the RG58 through the 2 ft of RG141. The results are as follows: At the load end of the RG58 and the input to the RG141: 69.41 - j19.19, At the load end of the RG141: ........................................79.23 - j3.25. At the load end of the RG141 using the composite data: 81.21 - j1.25. The difference in the R values is only 1.98 ohms and in the X values is only 2 ohms. I consider this degree of error insignificant. Would you not agree? Walt |
On Mon, 20 Jun 2005 23:17:40 -0400, "Walter Maxwell"
wrote: I'd like to hear your comments. Hi Walt, On first pass, the results are fairly consistent, but with two exceptions. I am not sure if this is in my translation to file formats suitable for Mathcad, or if they lie in your process. Anyway, a general description: The granularity of 50Khz appears to not be fine enough to find all peak resonances for the 9 of the 11 within the band. I have rendered the data into a sequence of 11 curves (one curve for each height) I call "Q" where that quality factor relates to the ratio of RL to |XL|. This was merely a survey to glance at all the data at once and to observe how the Mathcad sheet was taking shape. To this point this could as easily be accomplished in Excel. Continuing, I noted that two sets of height data moved retrograde to the general trend. That general trend revealed a family of peaks that moved up-frequency as the antenna height was raised. Two of the peaks were out of the band. One was above the band (the lowest antenna height) and the second was below the band (the second lowest antenna height). Of these two, I would suspect that the first, or lowest antenna height, was a curve rising to peak at the second (anti)resonance - otherwise, the trend is progressive with two exceptions. Those exceptions are found in raising the antenna from 8' to 10' and from 14' to 16'. The peaks in each of these step changes move counter to the trend: down-frequency when the height is raised. Again, this may be entirely a transcription error of my own that I need to investigate further. The biggest frequency shift comes with (this is a presumption) lifting the antenna up off the ground to the one foot level. The next biggest shift comes with the elevation change to the two foot level - and so on with progressively smaller shifts in frequency shift and progressively sharpening of the curves as the antenna is hiked higher. 73's Richard Clark, KB7QHC |
"Richard Clark" wrote in message ... On Mon, 20 Jun 2005 23:17:40 -0400, "Walter Maxwell" wrote: I'd like to hear your comments. Hi Walt, On first pass, the results are fairly consistent, but with two exceptions. I am not sure if this is in my translation to file formats suitable for Mathcad, or if they lie in your process. Anyway, a general description: The granularity of 50Khz appears to not be fine enough to find all peak resonances for the 9 of the 11 within the band. I have rendered the data into a sequence of 11 curves (one curve for each height) I call "Q" where that quality factor relates to the ratio of RL to |XL|. This was merely a survey to glance at all the data at once and to observe how the Mathcad sheet was taking shape. To this point this could as easily be accomplished in Excel. Continuing, I noted that two sets of height data moved retrograde to the general trend. That general trend revealed a family of peaks that moved up-frequency as the antenna height was raised. Two of the peaks were out of the band. One was above the band (the lowest antenna height) and the second was below the band (the second lowest antenna height). Of these two, I would suspect that the first, or lowest antenna height, was a curve rising to peak at the second (anti)resonance - otherwise, the trend is progressive with two exceptions. Those exceptions are found in raising the antenna from 8' to 10' and from 14' to 16'. The peaks in each of these step changes move counter to the trend: down-frequency when the height is raised. Again, this may be entirely a transcription error of my own that I need to investigate further. The biggest frequency shift comes with (this is a presumption) lifting the antenna up off the ground to the one foot level. The next biggest shift comes with the elevation change to the two foot level - and so on with progressively smaller shifts in frequency shift and progressively sharpening of the curves as the antenna is hiked higher. 73's Richard Clark, KB7QHC Very interesting, Richard. I made a cursury check on the retrograde data, and it seems that the trend is in the original measured data. I compared readings of adjacent frequencies for two different heights where the retrograde occurs and found differences in original R values that I can explain only in the possibility of different degrees of soil wetness, because the measurements were not all taken on the same day. The date of each measurement is in the upper left corner of each page. Since the measurements were taken 22 years ago I can't remember whether I logged the rain vs non-rain days, and the original data is in obscure files in Florida. I would not have taken measurements during a rain, but the day after a rain the soil would still have been wetter than the day before the rain. Wetness is the only explanation I can think of for the jerk in the data. Are your Mathcad graphs in a format suitable for emailing? If so, I'd like to see them. Walt |
"Reg Edwards" wrote in message ... "Walter Maxwell" wrote Reg asked if I could send my data as an email, so I converted the file to text format to be able to present the data in full here in this msg. I checked to see that the tabular format remained intact, and it did in Outlook Express, so here it is. I hope the tabular format will remain intact in your browsers. Be sure to give your screen maximum width. If it doesn't, let me know and I'll resend in PDF format. Walt, W2DU Dipole Terminal Impedance Data Obtained From Measurements at Various Heights Above Ground in the Frequency Range from 14.0 to 15.0 MHz. Measurements Made be W2DU at the W2DU site in DeLand, Florida. ============================================ Data received as an extension to this message. Fills screen very nicely. Thank you very much Walter for your trouble. ---- Reg, G4FGQ =========================================== Fine, Reg, I hope you find the data of interest. Walt |
On Wed, 22 Jun 2005 15:31:07 -0400, "Walter Maxwell"
wrote: Wetness is the only explanation I can think of for the jerk in the data. Oh, where that comment might lead. :-) Are your Mathcad graphs in a format suitable for emailing? If so, I'd like to see them. Hi Walt, Sure, I will kit that up later today. 73's Richard Clark, KB7QHC |
On Wed, 22 Jun 2005 15:31:07 -0400, "Walter Maxwell"
wrote: I compared readings of adjacent frequencies for two different heights where the retrograde occurs and found differences in original R values that I can explain only in the possibility of different degrees of soil wetness, because the measurements were not all taken on the same day. Hi All, This is a life's lesson in the value of context and measurement, as well as in the discipline of taking notes. Walt's memory suggests a reason for the perturbation observed in the data, and it is not unreasonable. I would suggest that there is some (however slight) likelihood that the correlations may be backwards in that most of the days followed rain, and these perturbations were on dry days. Before or after is not the issue. Before or after is a matter of separability which is more important. With analysis, Walt's conjecture can be tested against the data and what it reveals about the impact the ground's proximity had on the antenna. His data, either way, already supports that ground is measurable within the data that falls outside of the spread of noise and error. Even if Walt slipped an instrument reading or injected statistical noise, he did it so consistently that he was always in error in the same direction (this is called systematic error). This may impact the accuracy of the final answer, but it does not impact the thesis' general conclusion. What is more, even if such mischance occurred (and I doubt it), it is recoverable with one or several cardinal measurements to correct the earlier bias. This round of discussion also reveals that bad data is as good as good data. Those who discard results and tailor their reports stand a good chance of not discovering how to fix their problems when they are shown to be in serious error (which is to say they probably rejected good results). I pointed this threat out in another thread that linked to exhaustive ground data that showed hills composed of fresh water. 73's Richard Clark, KB7QHC |
Ian White wrote:
"The real technical question is how many, and how long, will be "just enough" for "here"?" Reminds me of the trailer house designer pulling out reaces until the whole projkect collapses, then rebuilding with only the last brace removed reinstalled. You don`t need any radials with a horizontal dipole. Broadcasters are launching ground waves to reach a local audience. Amateurs may want ro reach DX with sky waves. For radials under an earth mounted vertical, there`s no magic number or length. You can add to the count until resistance elimination fades. You can lengthen them until the current at their tips is almost zero. Or, you can just decide how much you will spend on wire. I read that quantity of radials is better than longer radials. If you want some idea of how conductive soil is, I read that a Variac, ground rods , ammeter and voltmeter is the way to go. Adjust current between the rods to one ampere with the Variac. Resistance between the rods is then the volts between them. Terman has already supplied Table 22-1 "TYPICAL GROUND CONSTANTS" on page 308 of his 1955 edition for estimating dielectric constant and ground conductivity. At high frequencies, poor ground conductivity takes eome energy from the reflected wave and the combined direct and reflected wave can`t be a complete cancellation. The direct wave alone is stronger than its combination with an out of phase wave. Ground wave propagetion fades in a short distance at high freqiuencies. So what use does the DXer have for soil conductivity? Isn`t something like Terman`s Table good enough, unless he is considering laying his antenna on or near the soil? Best regards, Richard Harrison, KB5WZI |
Walter Maxwell wrote:
Hasn't the copyright expired on material published in 1937? Hm. The way I read http://www.copyright.gov/circs/circ1.html#hlc, it has. It looks to me like the original copyright was good for 28 years and for copyrights originally issued in 1937, renewal (if done) was good for another 28. That would put it in the public domain after 1993. I'd sure appreciate comments from someone who's actually familiar with the law -- it's pretty convoluted and I'm not at all confident about my interpretation. Roy Lewallen, W7EL |
On Wed, 22 Jun 2005 16:13:55 -0700, Roy Lewallen
wrote: Walter Maxwell wrote: Hasn't the copyright expired on material published in 1937? Hm. The way I read http://www.copyright.gov/circs/circ1.html#hlc, it has. It looks to me like the original copyright was good for 28 years and for copyrights originally issued in 1937, renewal (if done) was good for another 28. That would put it in the public domain after 1993. I'd sure appreciate comments from someone who's actually familiar with the law -- it's pretty convoluted and I'm not at all confident about my interpretation. True it gets very complicated, especially when the likes of Disney get an act through Congress to copyright Mickey Mouse forever. http://writ.news.findlaw.com/comment..._sprigman.html Unfortunately, the Supreme Court was not interested in the constitutional aspects of this monstrosity and let it stand. The average citizen can afford to bribe his local officials (democracy in action), but when it comes to Congress, you need real money. Publish the paper Walt, the authors are all gone (I think, but you know better than I) the IRE is gone too; what are they going to do, come back from the grave and sue you? |
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