Re: Picofarad Capacitor Standard

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Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, December 10, 2003 4:47 PM
Subject: Re: Picofarad Capacitor Standard


 > Original poster: Ed Phillips <evp-at-pacbell-dot-net>
 >
 > "Oh, Ho.... the standard capacitor thing..
 > Check out NBS Circular 74... it has how to build standard capacitors...
 > As a practical matter, if you're working at a known frequency, a long
 > coaxial line might be the best approach, because, especially in the
 > shorted
 > form, it has a well defined value, with end effects taken care of.
 > Cragg"
 >
 > Make that OPEN, not shorted!  A shorted line is a shorted line if it is
 > very much less than a quarter wavelength long!


I did say a "long coaxial line"... The idea is to make the line long enough
so that end effects are negligible, and there are better analytical
solutions for a shorted coaxial line than for an open (the math for the
actual end, not the transmission line itself)