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From: Bill KT4YE
Date: 15 Dec 2002
Time: 09:57:11
Remote Name: 12.93.230.245
Hi Alan<><><> Well, I've been sending and reciving radio signals for nigh onto 45 years and never consciously used Displacement Current even once. I did, however, use (and occasionally misused) thousands of capacitors whose INSIDES (supposedly) CONTAINED Displacement Current. <><><>I didn't care. All I wanted was a capacitor. <><> But, as I noted in my post to David, when we attempt to turn a capacitor "inside out" and use its giblets in ANTENNA engineering design, we seem to run into problems. <><><> One way to understand those problems is by analyzing a capacitor as a short transmission line. That's what I did in the article, and believe that I have shown that a reasonable model of a capacitor is that of a very short transmission line. <><><>BTW, you noted in a previous post that you believe that Epsilon dD/dt (ie displacement current) is present in transmission lines also. <><><> (I apologize for not noting that earlier.)<><><> You'll recall that one of my criticisms of the "classical proof" of the existence of Displacement Current was that it relied on a UNIFORM E field. <><><> You have responded (with some merit) that in an itsy bitsy (by wavelength standards) capacitor, the field can be considered uniform. <><><>HOWEVER, in a fractional-wavelength transmission line, the E fields will NOT be Uniform. In this case, the classical proof seems to fall completely apart, and Displacement Current would NOT be proven to exist. <><><> 73 Bill KT4YE