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Roy Lewallen wrote:
That's all very nice. Let's see if it's useful for anything. A while back, Cecil posted a model of a base loaded vertical antenna. It has an inductor which is vertically oriented. The bottom of the inductor is 1 foot from the ground and the inductor is 1 foot long and six inches in diameter. Inductance is 38.5 uH and it's self resonant at 13.48 MHz. (Moving it very far from ground changes the resonant frequency to 13.52 MHz.) What's it's velocity factor, and how did you calculate it? 13.48 MHz is not exactly the self-resonant frequency of the coil. At 13.48 MHz, the one foot bottom section is 0.0137 wavelengths long, i.e. 4.9 degrees. So the coil occupies 85.1 degrees, i.e. 0.236 wavelength. The coil length is coincidentally also one foot so the velocity factor is 4.9/85.1 = 0.058. -- 73, Cecil http://www.qsl.net/w5dxp |