Re: Vf,Zo,R,G,L,C.....

To: tesla-at-pupman-dot-com
Subject: Re: Vf,Zo,R,G,L,C.....
From: W Y Liu <eenwyl-at-sun.leeds.ac.uk> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Wed, 30 Dec 1998 21:07:58 -0700
Approved: twf-at-verinet-dot-com

> 
> >My line is very lossy.  I add the DC resistance as the series R and
> >adjusted the shunt conductance until the Q of the line matches what my coil
> >measures.  I have seen a number of equations for the lossless cases but
> >haven't seen any for the lossy case.  I assume they are not easy...
> 
> 

Sorry to suddenly appear here!  I guess, at frequencies above a few mega
hertz, R >> j*2*Pi*f*L and similarly j*2*Pi*f*C >> G.  There is no need to
consider R and G. Is it true ??  If your problem is not connected with
long-distance power transmission, is it more reasonable to treat a 
conductive transmission medium as lossless line when the frequency is 
sufficient high ?  

With regards to the matching problem, is it not possible to simply correct
the phase by using quarter-wave line, or open-circuit stub or .... ??  I am 
not sure if the "Q of the line matches" problem is simply "the impedance 
matching problem" that maximizes the power transfer through the transmission
medium under consideration.

I guess the simplest transmission line model has ignored the magnetic coupling
between two neighbouring lines, and in other words, it ignores the phase
velocity. In a non-pancake coil placed well above the ground, the coupling
between two neighbouring turns are normally more dominant than the coupling 
between the transmission line and the ground. This does not seems to be the 
case of the simple transmission line (although the stationary wave effects 
are still there).  But the simple planer (lossy coupled) pancake coil may 
be modeled (very very roughly) by the simple transmission line equations,
according to my  findings from the eesof simulations and actual measurements
above 18GHz.

I hope this will help!