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#11
December 4th 03, 11:42 PM
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Richard Clark wrote:
On Thu, 4 Dec 2003 11:08:21 -0600 (CST), (Richard Harrison) wrote: Yuri Blanarovich posted ON4UN`s Fig 9-22 from "Low-Band DXing". 45-degrees of the 90-degree total length of a center-loaded whip comes from the loading coil. Current tapers cosinusoidally from 1A at the drivepoint to 0A at the tip. Hi Richard, First, and unfortunately, the antenna offered was never anywhere close to 45° tall. The one Yuri posted barely stood 20° tall. Second, Yuri's complaint centered on the notion of Modeling, not measuring. He was making a plea to improve the accuracy and efficiency of Modelers (all of this is EZNEC implicit, or by extension NEC generically). Yuri never demonstrated the so-called cosinusoidal variation in either Models or in Measurement. In fact, Yuri never demonstrated ANY variation in current along ANY radiator. Third, the argument of lumped or distributed circuit properties had been answered with a protocol BEFORE the argument started. The protocol offered every bit of correlation to ON4UN's drawings. Fourth, this correlation did not demonstrate a slavish equality to the so-called cosinusoidal variation, but rather demonstrated a conceptual agreement. In fact, the Model data shows a divergence from that curve. Fifth, no one has bothered to demonstrate anywhere, that with the protocol, that it is or is not born out in measurement. Six, the differences of Models employing the protocol and those not employing it shows about 0.5dB difference. This responds to the original complaint of Yuri, in that no remarkable efficiencies are gained or lost by this debate. To make matters worse, no Measure of differences has been made to accept or dismiss this Model either. This of course returns us to methods and accuracies, and given the forecast of 0.5dB, the prospects of that turning into a metaphysical freak show are more prominent than field tests resolving it in the noise. 73's Richard Clark, KB7QHC Bravo. Pretty much sums it all up in a nutshell. No one has shown an example of gross modeling error to date. No examples, no beef is served. MK -- http://web.wt.net/~nm5k |
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