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You might do well to read his (Cebik's) articles at :
http://www.cebik.com/radio.html He has quite a few dealing with the effects of different radial systems for vertical antennas. Food for thought and it might save you time and back breaking labor. 73 Dave =========================== Without any doubt, Cebik is the finest author on radio antennas. The extent of coverage of practical subject matters, numerical accuracy and use of the English language are beyond reproach. How he manages to find time even to keep his web-site in good working order is amazing. But even for the above-average-intellect amateur, the amount of detail is too excessive to take in. Few people have time available for a complete study. And I'm an approaching, still willing to learn, octagonarian. What is needed is a very much abbreviated summary, just the essentials of his works. Perhaps in small book form. But this can be produced, without unintentional distortion, only by Cebik himself. Does such a work exist? ======================= I have searched without success for the behaviour of simple antennas in the presence of so-called poor ground soils. Can't find much in Cebik except doubtful, expensive computer programs. The 'constants' of ground soils are Resistivity (Conductivity), Permittivity and Permeabilty. (In the absence of magnetic material such as iron in the soil permeability can be neglected.) It is generally accepted that ground loss increases as resistivity increases above that of salt sea water. But this cannot be universally true. Taking the extreme case of soils which approach insulators (solid granite rock and arid desert sands) it is obvious soil loss falls again to very low values. There MUST be values of resistivity at which soil losses are at a maximum but which reduce at higher values of resistivity. Here we are concerned with buried ground radials. It is submitted that maximum ground loss occurs at lower soil resistance values than are upposed - if they are supposed or imagined at all! Suppose soil resistivity is 377 ohm-metres, not a very high value, but it happens to completely absorb, without reflection, radio waves received from an antenna. Is this a suitable candidate for maximum loss in the ground? The statement, for simplicity, ignores permittivity and the angle at which radiation strikes the ground. But you get the idea. Has anyone any info on this subject? Of course, I may be trolling, just to catch old-wives. ;o) ---- Reg, G4FGQ |
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