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Gene Fuller wrote:
You have really lost it. I gave you the exact quote, and you then proceed to talk about something else. Your quote doesn't mean what you think it means. The velocity factor equation is appropriate for quarterwave resonance *and* any other length at the same frequency. The graph in the next column over shows coils of 10,000 turns per wavelength. It does NOT limit them to any length so your argument is bogus. Their goal was to find a VF equation that worked for quarterwave resonance but it works for a lot more than quarterwave resonance. It holds for any length as can be seen from Fig. 1. So let's throw the topic back to you. Too late, I asked you first. Where are the laws of physics to back up your assertions? Certainly not contained in the Corum papers. Please provide some reference that asserts that the VF of a coil varies with its length while keeping all other parameters constant. The coil being modeled is 48 turns per foot. The wavelength is 246 feet. 48*246 = 11,808 turns per wavelength. That's on the Corum chart. There is NO minimum or maximum length requirement or constraint. According to the paper, the velocity factor is within 10% no matter what the length of the coil. So holding all the variables constant in the velocity factor equation and changing only the length is a valid way to calculate the approximate delay through the coil. It's the best way that we have so far. It is infinitely better than using a signal with unchanging phase to try to measure phase shift. So where and how does the Vf transition occur? Just as in a transmission line, a VF transition occurs at an impedance discontinuity. For a complete helical antenna, there is no impedance discontinuity. For an antenna containing a coil and wire, there is an impedance discontinuity at the coil/wire interface. -- 73, Cecil http://www.qsl.net/w5dxp |
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