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October 21st 04, 09:05 PM
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"Chuck" wrote in message news:fVSdd.9064$6P5.7971@okepread02... wrote in message news:bMDdd.293802$3l3.275124@attbi_s03... "Chuck" wrote in message news:XrBdd.8254$6P5.7645@okepread02... snip. I'm not sure if I follow this correctly... please elaborate further. Certainly To attain maximum gain per unit length the model dimensions were all variables as was the number of elements. Not only was the driven element current often less than another element in the array it was sometimes found that the maximum current element required a diameter of a few thousanths that was not sufficient to carry 1Kw.! Obviously the gain attained was over ruled by the inability of the element to meet operational requirements. I might add that I use fibre fishing rods for my antennas where I can apply the correct wire diameters ( or aluminum foil) to an array without being encumbered by mechanical restrictions. This removes me from the normal restrictions applied to antennas where element diameter is pre-controlled for mechanical reasons which often conflict with scientific requirements The above statement does conflicts with your assesment stated above regarding critical coupling but this is what I found and I will leave it at that Regards Art. Hi Art, Ok, I'm always open minded to learn something new... Wow,,,...... there are not many people around who could say that !. Since 99.999% of things presented as new are incorrect most experts have determined that the odds favor them if they label EVERYTHING new as in error. If something comes along that is really new they always have the comment ' I knew about that a long while ago" to fall back on. I'd like to establish a few things, though. First of all, what modeling program are you using? Beasely AOP This is the professional version that has more than enough segments and variable dimensions available to lesson the chances of human input errors plus to handle elements that were in close proximetry to each other, together with 'Sommerfield ground' handling capabilities. Is your empirical data consistent with the models? Not measured, my thought were that NEC would always be closer than field measurements generated by an amateur. How are you ascertaining your empirical data? How are you determining the current amplitudes: By model? Or empirically? By model, The program provides % of max current at every segment, phase and all that good stuff And what are the machinations that demand ultra-thin wires to establish the gain? Go for 80 % gain and the rest (20% ) for swr Added half a dozen elements All dimensions variable except boom length and perfect ground height Remove one element at a time until max gain point is obvious Note all dimensions are kept variable at all times. You can email me if you care to not discuss these things in an open forum. Not necessary, This is the very reason I posted in the first place ! The program shows that the normal 2 element is not the optimum in that a polygon of vectors beats a triangle of vectors. At the same time with added elements you get diminishing returns in std and conventional forms. The program showed that 1 to 1.5 dbi was available over the standard 2 element on the same length boom.if one could overcome mechanical restraints. (I was comparing to a Beasely example of what gain could be attained for two elements on a 7 foot boom) Now that is not the end of the experiment as I cannot verify the accuracy of the program, because I did not write it, and I certainly cannot say that my modelling aproach is without error since that is what many 'experts' point to if they don't like the results. It was for that reason I asked if any similar data had been made available for boom length by reputable programmers and antenna 'experts' for comparison purposes ., If these initial results were quoted as accurrate there would be howls from all the resident antenna ' experts" and I would immediately be placed in the six foot hole that they have been trying to put you in for the last eight years Art 73, de Chuck, WA7RAI wa7rai at cox dot net |
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