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On Sat, 25 Jun 2005 07:56:38 +0000 (UTC), "Reg Edwards"
wrote: "Richard Clark" wrote in message .. . You are in farm country where the annual rainfall is 835mm. Where the mean temperature is 12.8°C. Where the soil is 20% sand, 65% silt, and 15% clay. What is the Conductivity in the 80M band? Answer: 30 mS You are in farm country where the annual rainfall is 360mm. Where the mean temperature is 4.9°C. Where the soil is 65% sand, 20% silt, and 15% clay. What is the Conductivity in the 80M band? Answer: 30 mS You are in farm country where the annual rainfall is 790mm. Where the mean temperature is 6.9°C. Where the soil is 31% sand, 33% silt, and 36% clay. What is the Conductivity in the 80M band? Answer: 15 mS ==================================== I don't know. And neither do you or anybody else. Such answers above have been know for decades. If you DID know you would not have the foggiest idea what to do with the data anyway. I might! You might? With emphasis too. Now if that isn't a firm declaration to end the pursuit in "How to measure soil constants at HF." In point of fact, you simply validate my premise: Let's draw a chord between 3 soil samples to see how fruitless knowing "How to measure soil constants at HF" really is As you struggled on: There's missing data. You forgot the iron oxide content and soil permeability. There is so much missing information as: What is it to an average of one skin depth in YOUR garden, old son? To this point all method and no results. By contrast, Walt provided both, and his data shows a continuity to your pronouncement about the wavelength shortening of radials adjacent to the ground - something you proclaimed no antenna measurement could achieve. Walt's method necessarily includes one skin depth (and more) that your scraping at the veneer of soil could never model. He doesn't have to worry about temperature, moisture, time of day, season, iron oxide content, or permeability - it comes free with the attempt and you don't have to haul mud into the kitchen. Do I hear John Cleese muttering something about the Bloody Obvious? 73's Richard Clark, KB7QHC |
Roy, surely you realise that all depends on soil conductivity and
permittivity which B, L & E forgot to determine before leaving the site. 30 years previously, around 1905, Sommerfeld (and others) had produced a significant report showing the importance of ground characteristics on radiation and propagation at LF and below. Which B, L, & E ought to have been aware of if they had known what they were about. You should concentrate your thoughts on HF and above, not on LF and VLF distractions. Different characteristics prevail at HF at which frequencies amateurs are most concerned. ---- Reg |
Reggie,
The following is so full of glaring contradictions - well, you can rely on me to point them out. :-) On Sat, 25 Jun 2005 18:34:17 +0000 (UTC), "Reg Edwards" wrote: Roy, surely you realise that all depends on soil conductivity and permittivity which B, L & E forgot to determine before leaving the site. You have thoroughly refuted any intimate knowledge of their paper, it goes unread by you, and yet you "know" this for a fact. Or perhaps that is elevating your prose upon to an unwarranted pedestal. 30 years previously, around 1905, Sommerfeld (and others) had produced a significant report showing the importance of ground characteristics on radiation and propagation at LF and below. Which B, L, & E ought to have been aware of if they had known what they were about. However, your earlier reference to LF from Sommerfeld (and others) is then wholly negated by you with: You should concentrate your thoughts on HF and above, not on LF and VLF distractions. Different characteristics prevail at HF at which frequencies amateurs are most concerned. Back in 1905, they called the frequencies above 1MHz VHF.... So, our trio, B,L, & E could just as easily had dismissed this work as you have? Such legerdemain. Sir Kelvinator asks, "Got any data, Reggie?" This quality of fence sitting - arguing both sides against the middle - is classic Punchinello. 73's Richard Clark, KB7QHC |
Reg Edwards wrote:
Roy, surely you realise that all depends on soil conductivity and permittivity which B, L & E forgot to determine before leaving the site. It just isn't sinking in, is it? It depends on the conductivity and permittivity to a skin depth or more, which was impossible for them to determine. A surface measurement wouldn't have provided the necessary information. Measurement of ground wave attenuation to another location would have included ground with a variety of possible characteristics different from those in the immediate vicinity. 30 years previously, around 1905, Sommerfeld (and others) had produced a significant report showing the importance of ground characteristics on radiation and propagation at LF and below. Which B, L, & E ought to have been aware of if they had known what they were about. I'm sure they were. But the paper has nothing to do with propagation. What makes you think it does? They certainly did know about the effect of conductivity. In a theoretical analysis at the beginning of their paper they calculated expected radial ground currents for several different ground conductivities, and explain how current is distributed in the ground with conductivity being a factor. The radial ground current analysis was later found to be in error(*), but it's still considerably closer than the results I've seen from your analysis and program. You should concentrate your thoughts on HF and above, not on LF and VLF distractions. Different characteristics prevail at HF at which frequencies amateurs are most concerned. That's a bizarre admonition from someone constantly harping about how many radials American AM broadcasters use. I am indeed most interested in HF, where skin depth is on the order of 12 feet for average soil, and measurement of surface conductivity and permittivity is pretty useless. Incidentally, since you haven't read their paper, you probably don't know that the BL & E measurements were done at 3 MHz, which is HF. (*) To my knowledge, no one has developed a method of calculating radial currents or ground system losses with even approximate accuracy other than with numerical analysis such as used by NEC-4. Many years ago I spent a couple of years of spare time in a technical library looking for just such an analysis without success. Reg's method is delightfully simple but gives results which are very wrong. Roy Lewallen, W7EL |
I wrote:
"Another (option) would be to find some curves which have already been constructed." Found some curves in Pete Saveskie`s "Radio Propagation Handbook" on pages 15, 17, and 19. They are from CCIR and may be available from them. They are for field strengths over sea water, good earth, and poor earth at 16 frequencies from 100 KHz to 10 MHZ. Best regards, Richard Harrison, KB5WZI |
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