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On 28 Apr 2006 13:28:56 -0700, "K7ITM" wrote:
Oh, Richard, Richard... Hi Tom, A smaller wire diameter has MORE inductance, not less, in the same environment. Yes, I did invert the relation of thickness to inductance - for a short wire. However, the feedpoint observation speaks of common results offering a different perspective. This is the question. It does not intuitively follow to describe less capacitance for the same size, but now thinner antenna makes an antenna more capacitive, does it? [A transform is at work.] Think for a moment about coax: reduce the inner conductor diameter, and the impedance goes up while the propagation velocity stays the same. This analogy begins to break down for antennas in that as the antenna grows thinner/thicker, the propagation velocity does change. On the other hand, and agreeing with your example, Z tracks (lower w/thicker) with an antenna. This is in conflict. That means that C goes down and L goes up. with a proviso: I don't think that simple concepts of the antenna behaving like a TEM transmission line are going to cut it here, and I'll wait for a better explanation than that. No, it didn't. For an antenna with an with an element circumference of 0.001 wavelength, the Vf is 0.97 to 0.98. Compared to an antenna with an element circumference of 0.1 wavelength, the Vf is 0.78 to 0.79. Velocity factor is a property of the capacitor's insulative medium (relative permittivity), which has never changed. [I would argue that the medium has in fact changed by the presence of the radiator, but that is another thread.] Large structures near resonance confound small component analytical results. So, we will both wait for Reggie to explain it in what he calls english; or for Cecil to explode with a new SWR analysis. 73's Richard Clark, KB7QHC |
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